Data Sheet

INTEGRATED CIRCUITS
SC28L202
Dual universal asynchronous
receiver/transmitter (DUART)
Product data sheet
Supersedes data of 2004 Apr 16
2005 Nov 01
Philips Semiconductors
Product data sheet
Dual universal asynchronous receiver/transmitter
(DUART)
SC28L202
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PIN CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PIN CONFIGURATION FOR 80XXX BUS INTERFACE (INTEL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CONFIGURATION FOR 68XXX BUS INTERFACE (MOTOROLA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OVERALL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRIEF DESCRIPTION OF FUNCTIONAL BLOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UARTs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitters and Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Character and Address Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Modes and Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DETAILED DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/O Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UART Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arbitrating Interrupt Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROGRAMMING THE HOST INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER DESCRIPTION AND PROGRAMMING NOTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Registers that control Global Properties of the 28L202 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCCR – Global Configuration Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCCR(7:6) DACKN Assertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCCR(5:3): Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCCR(2:1): Interrupt vector configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCCR(0): Interrupt Status Masking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SFSR A and B Special Feature & Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SFSR(7:4) Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SFSR(3) Status of loop back error check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SFSR(0) Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRR Test and Revision Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRR[7] Test 2 Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRR[6:0] – Chip Revision Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STCR – Scan Test Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SES – System Enable Status Register, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EOS – Enhanced Operation Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UART Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
These registers are generally concerned with formatting, transmitting and receiving data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR0 – Mode Register 0, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR0[7] Fixed length Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR0[5:4] – Tx interrupt fill level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR0[3] – FIFO Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR0[2:0] – Legacy Baud Rate Group Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 – Mode Register 1, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[7] – Receiver Request to Send (hardware flow control) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[6] – Receiver interrupt control bit 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 [5] – Error Mode Select and sub modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[4:3] – Parity Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[2] – Parity Type Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[1:0] – Bits per Character Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2 – Mode Register 2, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[7:6] – Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[7:6] = b’00 Normal Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[7:6] = b’01 Automatic Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[7:6] = b’10 selects local loop back diagnostic mode. In this mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2 [7:6] = b’11 Selects the Remote Loop back diagnostic mode. In this mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[5] Transmitter Request to Send Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[4] – Clear to Send Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2[3:0] – Stop Bit Length Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Philips Semiconductors
Product data sheet
Dual universal asynchronous receiver/transmitter
(DUART)
SC28L202
MR3 – Mode Register 3, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR3[7 & 6] Xon/Xoff Character Stripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR3[5:4] Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR3[3:2] Xon/Xoff Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR3[1:0] Address Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RxCSR – Receiver Clock Select Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TxCSR Transmitter Clock Select Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rx and Tx Clock Select Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CRx – Command Register Extension, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR[7] – Lock Tx and Rx enables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR[6] – Enable Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR[5] – Enable Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR[4:0] – Miscellaneous Commands (See Table below) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMMAND REGISTER EXTENSION TABLE A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR – Channel Status Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[7] – Received Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[6] – Framing Error (FE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[5] – Parity Error (PE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[4] – Overrun Error (OE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR [3] – Transmitter Idle (Tx Idle) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[2] – Transmitter Ready (TxRDY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[1] – RxFIFO Full (RxFULL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR[0] – Receiver Ready (RxRDY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR – Interrupt Status Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[7] – Input Change of State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[6] Fixed Watchdog Time-out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[5] – Address Recognition Status Change. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[4] – Xon/Xoff Status Change. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[3] – Counter Timer Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[2] – Change in Channel Break Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[1] – RxINT. (Also Rx DMA hand shake at I/O pins) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[0] – TxINT. (Also Tx DMA hand shake at I/O pins) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR – Interrupt Mask Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[7] COS enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[6] Fixed Watchdog Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[5] Address recognition enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[4] Xon/Xoff Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[3] Counter/Timer Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[1] Receiver (Rx) Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR[0] Transmitter (Tx) Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RxFIFO – Receiver FIFO, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TxFIFO – Transmitter FIFO, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RxFIL – Receiver FIFO Interrupt Level, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RxFL – Receiver FIFO Fill Level Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TxFIL – Transmitter FIFO Interrupt Level A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TxEL – Transmitter FIFO Empty Level Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Registers for Character Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XonCR – Xon/Xoff Character Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XoffCR – Xoff Character Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ARCR – Address Recognition Character Register A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XISR – Xon–Xoff Interrupt Status Register A and B (Reading this register clears XISR(7:4)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XISR[7:6] Received X Character Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XISR[5:4] Automatic transmission Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XISR[3:2] TxD Condition of the automatic flow control status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XISR[1:0] TxD X character Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WCXER Watch Dog, Character, Address and X Enable Register – A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Programmable Counters, Timers and Baud Rate generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PBRGPU – Programmable BRG Timer Reload Registers, Upper 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PBRGPL – Programmable BRG Timer Reload Registers, Lower 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTCS 0 and 1 – Counter Timer clock source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTVU – Counter Timer Value Registers, Upper 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTVL – Counter timer Value Registers, Lower 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PBRGCS – Programmable BRG Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTPU Counter Timer Preset Upper 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTPL Counter –Timer Preset Low 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Philips Semiconductors
Product data sheet
Dual universal asynchronous receiver/transmitter
(DUART)
SC28L202
Registers of the Arbitrating Interrupt System and Bidding control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ICR – Interrupt Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UCIR – Update CIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CIR – Current Interrupt Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IVR – Interrupt Vector Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modification of the IVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GICR – Global Interrupting Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GIBCR – Global Interrupting Byte Count Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GITR – Global Interrupting Type Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GRxFIFO – Global RxFIFO Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GTxFIFO – Global TxFIFO Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCRBRK – Bidding Control Register – Break Change, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCRCOS – Bidding Control Register – Change of State, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCRx – Bidding Control Register – Xon/Xoff, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCRA – Bidding Control Register – Address, A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCR C/T – Bidding Control Register –C/T, 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCRLBE – Bidding Control Register – Received Loop Back Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Registers of the I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCRL – Input Port Change Register Lower Nibble, A and B (n = A for A, n = B for B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCRU – Input Port Change Register Upper Nibble, A and B (n = A for A, n = B for B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPR – Input Port Register, A and B (n = A for A, n = B for B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCE – Input Change Detect Enable, A and B (n = A for A, n = B for B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/OPCR 0 – I/O Port Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/OPCR 1 – I/O Port Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/OPCR 2 – I/O Port Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I/OPCR 3 – I/O Port Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOPR A and SOPR B – Set the Output Port Bits (OPR A and OPR B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ROPR A and ROPR B – Reset ROPR Output Port Bits (OPR A and OPR B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OPR – Output Port Register, A and B (n = A for A, n = B for B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
THE REGISTERS FOR COMPATIBILITY WITH PREVIOUS DUARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER DESCRIPTIONS Mode Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 Mode Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 A[7] – Channel A Receiver Request–to–Send Control (Flow Control) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1[6] – Receiver interrupt control bit 1. See description under MR0[6]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 A[5] – Channel A Error Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 A[4:3| – Channel A Parity Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 A[2] – Channel A Parity Type Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR1 A[1:0] – Channel A Bits Per Character Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MR2 Mode Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[7] – Received Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[6] – Channel A Framing Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[5] – Channel A Parity Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[4] – Channel A Overrun Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[3] – Channel A Transmitter Empty (TxEMT A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[2] – Channel A Transmitter Ready (TxRDY A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[1] – Channel A FIFO Full (FFULL A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR A[0] – Channel A Receiver Ready (RxRDY A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SR B – Channel B Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSR A – Channel A Clock Select Register CSR A [7:4] – Channel A Receiver Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSR Clock Select Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSR A [3:0] – Channel A EXTERNAL Transmitter Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSR B [7:4] – Channel B Receiver Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CSR B [3:0] – Channel B Transmitter Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rx FIFO Register. For characters shorter than 8 bits the unused bits are set to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tx FIFO register. For characters shorter than 8 bits the unused bits are set to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR A and B Command Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CR Command Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMMAND REGISTER TABLE A and B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCR Input Port Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCR [7:4] I/03A, I/O2 A, I/O1 A, I/O0 A Change–of–State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IPCR [3:0] I/O3 A, I/O2 A, I/O1 A, I/O0 A logical level of I/O pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR Auxiliary Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR[7] – Baud Rate Generator Set Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR[6:4] – Counter/Timer Mode And Clock Source Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR[3:0] – I/O3 A, I/O2 A, I/O1 A, I/O0 A Change-of-State Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Philips Semiconductors
Product data sheet
Dual universal asynchronous receiver/transmitter
(DUART)
SC28L202
ISR – Interrupt Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[7] – Input Port Change Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[6] – Channel B Change In Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[5] – Rx B Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[4] – Tx B Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[3] – Counter Ready. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[2] – Channel A Change in Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[1] – Rx A Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ISR[0] – Tx A Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMR – Interrupt Mask Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTPU Counter Timer Preset Upper (Counter/Timer 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTPL Counter –Timer Preset Lower (Counter/Timer 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTVU Counter Timer Value Upper (Counter/Timer 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CTVL Counter –Timer Value Lower (Counter/Timer 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IVR Interrupt Vector register in 68K mode and General purpose read write register in the x86 mode . . . . . . . . . . . . . . . . . . . . . . . . .
IPR Input Port Register I/O(6:0) A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OPCR Output Port Configuration Register. Controls [7:2] B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOPR – Set Bits in the OPR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ROPR – Reset Bits in the OPR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OPR Output Port Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER MAP DETAIL (based on 28L92) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REGISTER MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL TIMING CONSIDERATIONS FOR THE SC28L202 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DC ELECTRICAL CHARACTERISTICS (NOMINAL 5 VOLTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AC CHARACTERISTICS (NOMINAL 5 VOLTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DC ELECTRICAL CHARACTERISTICS (NOMINAL 3.3 VOLTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AC CHARACTERISTICS (NOMINAL 3.3 VOLTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TIMING DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Philips Semiconductors
Product data sheet
Dual universal asynchronous receiver/transmitter
(DUART)
SC28L202
LIST OF FIGURES
Figure 1.
80xxx TSSOP56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2.
68xxx TSSOP56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3.
Active area in 68K mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 4.
Reset Timing (80XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5.
Reset Timing (68XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6.
Bus Timing (80XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7.
Bus Timing (Read Cycle) (68XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 8.
Bus Timing (Write Cycle) (68XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 9.
Interrupt Cycle Timing (68XXX mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 10.
Port Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 11.
Interrupt Timing (80xxx mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 12.
Clock Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 13.
Transmitter External Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 14.
Receiver External Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 15.
Transmitter Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 16.
Receiver Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 17.
Wake-Up Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 18.
Test Conditions on Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TSSOP56: plastic thin shrink small outline package; 56 leads; body width 6.1 mm (SOT364-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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LIST OF TABLES
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
2005 Nov 01
Interrupt Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SC28L202 REGISTER BIT DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SC28L92 Register Addressing READ (RDN = 0) WRITE (WRN = 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Baud Rate Generator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Baud Rate (Base on a 14.7456 MHz crystal clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR 6:4 Field Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interrupt Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SC28L202 REGISTER BIT DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0(3)=1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0(3)=0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SC28L92 Register Addressing READ (RDN = 0) WRITE (WRN = 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Baud Rate Generator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0[3] = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver FIFO Interrupt Fill Level MR0[3] = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0[3] = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter FIFO Interrupt Fill Level MR0[3] = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Baud Rate (Base on a 14.7456 MHz crystal clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACR 6:4 Field Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
v
14
19
21
21
21
21
39
40
41
41
41
41
44
46
14
18
20
20
20
20
39
40
41
41
41
41
44
46
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
• Three character recognition system per channel, used as:
DESCRIPTION
The 28L202 is a high performance dual UART. Its functional and
programming features closely match but greatly extend those of
previous Philips dual channel UARTs. Its configuration on power up
is similar that of the SC26C92. Its differences from the SC26C92
are: 256-character receiver, 256 character transmit FIFOs, 3 V and
5 V compatibility, 8 I/O ports for each UART—16 total, arbitrating
interrupt system and overall faster bus and data speeds. It is
fabricated in an advanced 0.5 micron CMOS process.
It is a member of the
IMPACT
– General purpose character recognition
– Xon/Xoff character recognition
– Address recognition Wake up (multi-drop or ‘9 bit’) mode
– System provides 4 levels of automation on a recognition event
• Programmable data format
– 5 to 8 data bits plus parity and 9 bit mode
– Odd, even, no parity or force parity
line of Data Communications parts
– 9/16,1, 1.5 or 2 stop bits
Pin programming will allow the device to operate with either the
Motorola or Intel bus interface by changing the function of some pins
(reset is inverted, DACKN, and IACKN enabled for example).
• 16-bit programmable Counter/Timer
• Programmable baud rate for each receiver and transmitter
The Philips Semiconductors 28L202 Dual Universal Asynchronous
Receiver/Transmitter (DUART) is a single-chip CMOS-LSI
communications device that provides two full-duplex asynchronous
receiver/transmitter channels in a single package. It interfaces
directly with microprocessors and may be used in a polled or
interrupt driven system. The use of the Interrupt system provides
intelligent interrupt vectors.
selectable from:
– 27 fixed rates: 50 to 2.0 Meg baud (includes MIDI rate)
– Other baud rates via external clocks and C/T
– Programmable user-defined rates derived from a programmable
Counter/timer
– External 1X or 16X clock
• Parity, framing, and overrun error detection
• Line break detection and generation; false start bit detection
• Programmable channel mode
The operating mode and data format of each channel may be
programmed independently. Additionally, each receiver and
transmitter can select its operating speed as one of twenty-seven
fixed baud rates; a 16X clock derived from one of two programmable
counter/timers, or an external 1X or 16X clock. The baud rate
generator and counter/timer can operate directly from a crystal or
from external clock inputs. The ability to independently program the
operating speed of the receiver and transmitter make the DUART
particularly attractive for dual-speed channel applications such as
clustered terminal systems and bridges.
– Normal (full-duplex)
– Automatic echo
– Local loop back
– Remote loop back
– Multi-drop mode (also called ‘wake-up’ or ‘9-bit’)
• Multi-function 8 bit I/O input port per channel loosely assigned to
Each receiver and transmitter is buffered by 256 character FIFOs to
nearly eliminate the potential of receiver overrun, transmitter
underrun and to reduce interrupt overhead in interrupt driven
systems. In addition, a flow control capability (Xon/Xoff and
RTS/CTS) is provided to disable a remote transmitter when the
receiver buffer is full.
each channel.
– Can serve as clock or control inputs
– Change of state detection on eight inputs
– Inputs have typically >100 MΩ pull-up resistors
– Modem and DMA interface
Also provided on the 28L202 is a multipurpose 8-bit I/O for each
channel. These can be used as general-purpose I/O ports or can be
assigned specific functions (such as clock inputs or status and
interrupt outputs) under program control. Normally they will be used
for modem control and DMA interface. All ports have change of state
detectors and input sections are always active making output
signals available to the internal circuits and the control processor.
• Versatile arbitrating interrupt system
– Interrupt system totally supports ‘single query’ polling
– Output port can be configured to provide a total of up to six
separate interrupt type outputs that may be wire-ORed
(switched to open drain).
– Each FIFO can be independently programmed for any of 256
interrupt levels
The 28L202 is available in a 52–pin TSSOP package. For other
package options, contact Philips.
– Watch dog timer for each receiver
• Maximum data transfer rates: 1X – 3 Mb/sec, 16X – 2 Mb/sec
• Automatic wake-up mode for multi-drop applications
• Start-end break interrupt/status
• Detects break which originates in the middle of a character
• On-chip crystal oscillator
• Power down mode at less than 10 µa
• Receiver time-out mode
• Single +3.3V or +5V power supply
FEATURES
• Member of IMPACT family: 3.3 V to 5.0 V , –40°C to +85°C and
80xx or 68k bus interface (I/M modes) for all devices.
• Bit-by-bit real time transmission error check for high data integrity
systems.
• Dual full-duplex independent asynchronous receiver/transmitters
• 256 character FIFOs for each receiver and transmitter
• Powers up to 9600 baud, 1 stop bit, no parity, 1 stop bit, interrupt
disabled, all I/O set to input.
• Pin programming to 68K or 80xxx bus interface
2005 Nov 01
1
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
ORDERING INFORMATION
Package
Type number
n mber
Name
Description
Version
plastic thin shrink small outline package; 56 leads;
body width 6.1 mm
SOT364-1
Temperat re range
Temperature
Industrial, VCC = +3.3 +5 V ± 10 %
SC28L202A1DGG
TSSOP56
Tamb = –40 °C to +85 °C
PIN CONFIGURATIONS
56 X2
VCC 1
VSS
2
55 X1/SCLK
VSS
2
55 X1/SCLK
A6
3
54 IRQN
A6
3
54 IRQN
A5
4
53 TXDA
A5
4
53 TXDA
A4
5
52 I/O0A
A4
5
52 I/O0A
A3
6
51 I/O1A
A3
6
51 I/O1A
VCC 1
RXDA
7
50 I/O2A
RXDA
7
50 I/O2A
RESET
8
49 I/O3A
RESETN
8
49 I/O3A
D7
9
48 I/O4A
D7
9
48 I/O4A
47 I/O5A
D6 10
D5 11
46 I/O6A
D5 11
46 I/O6A
D4 12
45 I/O7A
D4 12
45 I/O7A
D6 10
47 I/O5A
VCC 13
44 VSS
VCC 13
44 VSS
n.c. 14
43 VSS
n.c. 14
43 VSS
VSS 15
42 VCC
VSS 15
42 VCC
VSS 16
41 VCC
VSS 16
41 VCC
D3 17
40 I/O0B
D3 17
40 I/O0B
D2 18
39 I/O1B
D2 18
39 I/O1B
D1 19
38 I/O2B
D1 19
38 I/O2B
D0 20
37 I/O3B
D0 20
37 I/O3B
I /M 21
36 I/O4B
I /M 21
36 I/O4B
RXDB 22
35 I/O5B
RXDB 22
35 I/O5B
A2 23
34 I/O6B
A2 23
34 I/O6B
A1 24
33 I/O7B
A1 24
33 I/O7B
A0 25
32 TXDN
A0 25
32 TXDB
IACKN 26
31 RDN
IACKN 26
31 DACKN
VCC 27
30 WRN
VCC 27
30 RWN
VSS 28
29 CEN
VSS 28
29 CEN
SD00727
SD00728
Figure 1. 80xxx TSSOP56
2005 Nov 01
56 X2
Figure 2. 68xxx TSSOP56
2
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
PIN CONFIGURATION FOR 80XXX BUS INTERFACE (INTEL) (see Figure 1)
Symbol
Pin no.
Pin
type
Name and Function
I/M
21
I
Bus Configuration: When HIGH, configures the bus interface to the Conditions shown in this table.
D0–D7
20–17,
12–9
I/O
Data Bus: Bi-directional 3-State data bus used to transfer commands, data and status between the DUART and
the CPU. D0 is the least significant bit.
CEN
29
I
Chip Enable: Active-LOW input signal. When LOW, data transfers between the CPU and the DUART are
enabled on D0–D7 as controlled by the WRN, RDN and A6–A0 inputs. When HIGH, places the D0–D7 lines in
the 3-State condition.
WRN
30
I
Write Strobe: When LOW and CEN is also LOW, the contents of the data bus is loaded into the addressed
register. The transfer occurs on the rising edge of the signal.
RDN
31
I
Read Strobe: When LOW and CEN is also LOW, causes the contents of the addressed register to be presented
on the data bus. The read cycle begins on the falling edge of RDN.
A6–A0
3–6,
23–25
I
Address Inputs: Select the DUART internal registers and ports for read/write operations.
RESET
8
I
Reset: A HIGH level clears internal registers (SR A, SR B, IMR, ISR, OPR, OPCR), places I/O[7:0] A and B at
high impedance input state, stops the counter/timer, and puts Channels A and B in the inactive state, with the
TxD A and TxD B outputs in the ‘mark’ (HIGH) state. Sets MR pointer to MR1 9600 baud, 1 start, no parity and 1
stop bit(s). (See Reset table)
IRQN
54
O
Interrupt Request: Active-LOW, open-drain, output which signals the CPU that one or more of the eighteen (18)
maskable interrupting conditions are true.
IACKN
26
I
Interrupt Acknowledge: Active-LOW input indicates an interrupt acknowledge cycle. Usually asserted by the
CPU in response to an interrupt request. When asserted places the interrupt vector on the bus.
X1/SCLK
55
I
Crystal 1: Crystal or external clock input. A crystal or clock of the specified limits must be supplied at all times.
When a crystal is used, a capacitor must be connected from this pin to ground (see Figure 12).
X2
56
O
Crystal 2: Connection for other side of the crystal. When a crystal is used, a capacitor must be connected from
this pin to ground (see Figure 12). If X1/Sclk is driven from an external source, this pin must be open or not
driving more that 2 CMOS or TTL loads.
RxD A
7
I
Channel A Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH; ‘space’ is LOW.
RxD B
22
I
Channel B Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH; ‘space’ is LOW.
TxD A
53
O
Channel A Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in
the ‘mark’ condition when the transmitter is disabled, idle or when operating in local loop back mode. ‘Mark’ is
HIGH; ‘space’ is LOW.
TxD B
32
O
Channel B Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in
the ‘mark’ condition when the transmitter is disabled, idle, or when operating in local loop back mode. ‘Mark’ is
HIGH; ‘space’ is LOW.
I/O[7:0]A
45–52
I/O
General-purpose input and output ports channel A: The character of these pins is controlled by I/OPCR.
They may be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR
etc. All have change of state detectors and the input is always active. These pins are set to input only when
addressed from the low order 16 address space. When these pins are configured for interrupt type signals
(RxRDY, TxRDY, C/TRDY) They switch to open drain outputs. Each of these pins have a small pull-up ‘resistor’
that supplies approximately 5 µA of current.
I/O[7:0]B
33–40
I/O
General-purpose input and output ports channel B: The character of these pins is controlled by I/OPCR.
They may be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR
etc. All have change of state detectors and the input is always active. These pins are set to output only when
addressed from the low order 16 address space. When these pins are configured for interrupt type signals
(RxRDY, TxRDY, C/TRDY) They switch to open drain outputs. Each of these pins have a small pull-up ‘resistor’
that supplies approximately 5 µA of current.
VCC
1, 13,
27, 41,
42
Power
Power Supply (5 pins): +3.3 V or +5 V supply input ± 10%. Operation is assured from 2.97 V to 5.5 V.
Timing parameters are specified with respect to the VCC being at 3.3 V ± 10% or 5.0 V ± 10%.
VSS
2, 15,
16, 28,
43, 44
Power
Ground (6 pins)
n.c.
14
–
not connected
2005 Nov 01
3
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
CONFIGURATION FOR 68XXX BUS INTERFACE (MOTOROLA) (see Figure 2)
Symbol
Pin no.
Pin
type
Name and Function
I/M
21
I
Bus Configuration: When LOW configures the bus interface to the Conditions shown in this table.
D0–D7
20–17,
12–9
I/O
Data Bus: Bi-directional 3-State data bus used to transfer commands, data and status between the DUART and
the CPU. D0 is the least significant bit.
CEN
29
I
Chip Enable: Active-LOW input signal. When LOW, data transfers between the CPU and the DUART are
enabled on D0–D7 as controlled by the R/WN and A0–A6 inputs. When HIGH, places the D0–D7 lines in the
3-State condition.
R/WN
30
I
Read/Write: Input Signal. When CEN is LOW R/WN HIGH input a read cycle, when LOW a write cycle.
IACKN
26
I
Interrupt Acknowledge: Active-LOW input indicates an interrupt acknowledge cycle. Usually asserted by the
CPU in response to an interrupt request. When asserted places the interrupt vector on the bus and asserts
DACKN.
DACKN
31
O
Data Transfer Acknowledge: An open-drain active-LOW output asserted in a write, read, or interrupt
acknowledge cycle to indicate proper transfer of data between the CPU and the DUART.
A6–A0
3–6,
23–25
I
Address Inputs: Select the DUART internal registers and ports for read/write operations.
RESETN
8
I
Reset: A LOW level clears internal registers (SR A , SR B, IMR, ISR, OPR, OPCR), places I/O[7:0] A and B at
high impedance input state, stops the counter/timer, and puts Channels A and B in the inactive state, with the
TxD A and TxD B outputs in the mark (HIGH) state. Sets MR pointer to MR1, 9600 baud, 1 start, no parity and
1 stop bit(s). (See Reset Table)
IRQN
54
O
Interrupt Request: Active-LOW, open-drain, output which signals the CPU that one or more of the eighteen (18)
maskable interrupting conditions are true.
X1/SCLK
55
I
Crystal 1: Crystal or external clock input. A crystal or clock of the specified limits must be supplied at all times.
When a crystal is used, a capacitor must be connected from this pin to ground (see Figure 12).
X2
56
O
Crystal 2: Connection for other side of the crystal. When a crystal is used, a capacitor must be connected from
this pin to ground (see Figure 12). If Sclk is driven from an external source, this pin must be left open.
RxD A
7
I
Channel A Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH; ‘space’ is LOW.
RxD B
22
I
Channel B Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH; ‘space’ is LOW.
TxD A
53
O
Channel A Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in
the ‘mark’ condition when the transmitter is disabled, idle or when operating in local loop back mode.
‘Mark’ is HIGH; ‘space’ is LOW.
TxD B
32
O
Channel B Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in
the ‘mark’ condition when the transmitter is disabled, idle, or when operating in local loop back mode. ‘Mark’ is
HIGH; ‘space’ is LOW.
I/O[7:0]A
45–52
I/O
General-purpose input and output ports channel A: The character of these pins is controlled by I/OPCR.
They may be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR
etc. All have change of state detectors and the input is always active. These pins are set to input only when
addressed from the low order 16 address space. When these pins are configured for interrupt type signals
(RxRDY, TxRDY, C/TRDY) They switch to open drain outputs. Each of these pins have a small pull-up ‘resistor’
that supplies approximately 5 µA of current.
I/O[7:0]B
33–40
I/O
General-purpose input and output ports channel B: The character of these pins is controlled by I/OPCR.
They may be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR
etc. All have change of state detectors and the input is always active. These pins are set to output only when
addressed from the low order 16 address space. When these pins are configured for interrupt type signals
(RxRDY, TxRDY, C/TRDY) They switch to open drain outputs. Each of these pins have a small pull-up ‘resistor’
that supplies approximately 5 µA of current.
Vcc
1, 13,
27, 41,
42
Power
Power Supply (5 pins): +3.3 or +5V supply input ± 10% (4 Vcc Pins) ). Operation is assured from 2.97 V to
5.5 V. Timing parameters are specified with respect to the Vcc being at 3.3 V ± 10% or 5.0 V ± 10%.
Vss
2, 15,
16, 28,
43, 44
Power
Ground (6 Vss Pins)
n.c.
14
2005 Nov 01
not connected
4
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
the receivers and transmitters and may be delivered to I/O ports. It
has 8 programmable clock sources derived from internal and
external signals.
OVERALL DESCRIPTION
The SC28L202 is composed of several functional blocks. They are
listed in the approximate order of hierarchy as seen from the pins of
the device.
I/O ports
The SC28L202 is provided with 16 I/O ports. These ports are true
input and/or output structures and are equipped with a change of
state detector. The input circuit of these pins is always active. Under
program control the ports my display internal signals or static logic
levels. The functions represented by the I/O ports include hardware
flow control. Modem signals, signals for interrupt conditions or
various internal clocks and timing intervals. Noisy inputs to the I/O
ports are filtered (de-bounced) by a 38.4 KHz clock. Change of state
detectors are provided for each pin and are always available.
• Bus interface. 68K or x86 format
• Timing Circuits
• I/O Ports
• UARTs
• Transmitters and Receivers
• Transmitter real time error test
• FIFO Structures
• Arbitrating Interrupt Structure
• Character & Address Recognition
• Flow Control
• Test and Software compatibility with previous Philips (Signetics)
UARTs
The UARTs are fully independent, full duplex and provide all normal
asynchronous functions: 5 to 8 data bits, parity odd or even,
programmable stop bit length, false start bit detection. Also provided
are 256 byte FIFOs Xon/Xoff software flow. The BRG,
Counter-timer, or external clocks provide the baud rates. The
receivers and transmitters may operate in either the ‘1x’ or ‘16x’
modes.
UARTs
The control section recognizes two address schemes. One is the
subset of the other: a four (4) bit and an eight (7) bit address
spaces. The purpose of this is to provide a large degree of software
compatibility with previous Philips/Signetics UARTs.
BRIEF DESCRIPTION OF FUNCTIONAL BLOCKS
Bus Interface
The Two basic modes of Bus Interface
The bus interface operates in ‘68K’ or ‘x86’ format as selected by
the I/M pin. The signals used by this section are the Address, Data
bus, Chip select, read/write, Data acknowledge and Interrupt
acknowledge and Interrupt request. Assertion of DACKN requires
two edges of the Sclk after the assertion of CEN. The default mode
is the x86 mode. Pin or register programming may change it to the
68K mode.
Transmitters and Receivers
The transmitters and receivers are independent devices capable of
full duplex operation. Baud rates, interrupt and status conditions are
under separate control. Transmitters have automatic simplex
‘turnaround’. Receivers have RTS and Xon/Xoff flow control and a
three character recognition system.
Transmitter Real Time Error Check
This is a circuit used to verify that the correct data arrived at the
destination. It is done real time with one or two bit times of
programmable delay. The purpose is to relieve the processor of the
burden of byte-by-byte checking and the delay in sending a block of
data back for processor checking.
Timing Circuits
Crystal Oscillator
The crystal oscillator is the main timing element for the 28L202.
It is nominally set at 14.7456 MHz. Operation with a crystal as a
frequency standard is specified from 7 MHz to 16.2 MHz. The use of
an external clock allows all frequencies to 50 MHz. Clock prescalers
are provided to match various available system clocks to those
needed for baud rate generation.
The function is that the receiver returns the data received back to
the transmitting station where it is compared to a delayed version of
the data sent. If an error occurs, and interrupt may be generated for
the particular bit that is in error. This is essentially a loop back
condition where circuits internal to the UART delay and compare the
data.
NOTE: if an external clock is used X2 should not drive more
than 2 CMOS or 2 TTL equivalents.
Fixed Rate BRG
The BRG is the baud rate generator, is driven by the X1/Sclk input
through a programmable prescale divider. It generates all of the 27
‘fixed’ internal baud rates. This baud rate generator is designed to
generate the industry standard baud rates from a 14.7456 MHz
crystal or clock frequency. X1/Sclk frequencies different from
14.7456 MHz will cause the ‘fixed’ baud rates to change by exactly
the ratio of 14.7456 to the different frequency.
Counter-Timer
The two counter-timers are programmable 16 bit ‘down’ counters. It
provides miscellaneous baud rates, timing periods and acts as an
extra watchdog timer for the receivers. It has 8 programmable clock
sources derived from internal and external signals. It may also act
as a character counter for the receiver. Interrupts from the counter
timer are generated as it passes through zero.
Programmable BRG (PBRG)
This is another 16 bit programmable counter to generate only baud
rates or miscellaneous clock frequencies. Its output is available to
2005 Nov 01
It is suggested that a very high priority be set in the interrupt
arbitration bid control register for this interrupt when in use.
FIFO Structures
The FIFO structure is 256 bytes for each of the four FIFOs in the
DUART. They are organized as 11 bit words for the receiver and 8
bye words for the transmitter. The interrupt level may be set at any
value from 0 to 255. The interrupt level is independently set for each
FIFO.
FIFO interrupt and DMA fill/empty levels are controlled by the RxFIL
and TxFIL registers which may set any level of the from 0 to 255.
The signals associated with the FIFO fill levels are available to the
I/O pins (for interrupt or DMA) and to the arbitrating interrupt system
for ‘fine tuning’ of the arbitration authority.
Intelligent Interrupt Arbitration
The interrupt system uses a highly programmable arbitrating
technique to establish when an interrupt should be presented to the
5
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
data bus pins. Addressing of the various functions of the DUART is
through the address bus A(6:0). Data is presented on the 8-bit data
bus.
DACKN Cycle
When operating in the ‘68K’ mode, bus cycle completion is indicated
by the DACKN pin (an open-drain signal) going LOW. The timing of
DACKN is controlled by GCCR[7:6] where three time delays area
available. The delay begins with the falling edge of CEN. DACKN is
presented after 1/2 to three periods of the X1/SCLK. The minimum
time will be two edges of the X1/SCLK and will be realized when the
bus cycle begins just before the transition of X1/SCLK. Usually in
this mode the address and data are set up with respect to the
leading edge of the bus cycle. Timing diagrams for this mode are
drawn with DACKN in consideration. When CEN is withdrawn before
DACKN occurs, the generation of the DACKN signal and bus cycle
will be terminated. In this case, the bus timing will return to that of
Intel type timing for that particular cycle. This timing should not be
less than the minimum read or write pulse.
processor. The advantageous feature of this system is the
presentation of the context of the interrupt. It is presented in both a
current interrupt register and in the interrupt vector. The context of
the interrupt shows the interrupting channel, identifies which of the
18 possible sources in requesting interrupt service and in the case
of a receiver or transmitter gives the current fill level of the FIFO.
The content of the current interrupt register also drives the Global
Registers of the interrupt system. These registers are indirect
addresses (pointers) to the interrupt source requesting service.
Programming of Bid Control Registers allows the interrupt level of
any source to be varied at any time over a range of 256 levels.
Character and Address Recognition
The character recognition system is designed as a general-purpose
system. There is one for each UART. Each recognition block stores
up to three characters. The recognition is done on a byte boundary
and sets status and interrupt when recognition events occur. Three
modes of automatic operation are provided for the in-band flow
control and three modes of automatic operation are provided for
address recognition. Both in-band flow control and address
recognition may also be completely under the control of the host
processor.
The DACKN pin is an open-drain driver. At the termination of an
access to the L202 DACKN drives the pin to high impedance until
the next DACKN cycle. This will occur at the termination of the CEN
or IACKN cycle.
NOTE: The faster X86 timing may be used in the 68K mode IF the
bus cycles are faster than 1/2 period of the Sclk clock. Withdrawing
CEN before DACKN prevents the generation of DACKN. In this case
bus timing is effectively that of the X86 mode.
A subset of the recognition system is Xon/Xoff character recognition
and the recognition of the multi-drop address character. If Xon/Xoff
or multi-drop function is enabled the recognition system passes the
information about the recognition event to the appropriate receiver
or transmitter state machine for execution. In any case the
information about a recognition event is available to the interrupt
system and to the control processor.
When operating in the ‘x86’ mode DACKN is not generated. Data is
written on the termination of CEN or WRN whichever one occurs
first. Read data is presented from the leading edge of the read
condition (CEN and RDN both low).
Flow Control
Flow control is implemented in either the traditional RTS/CTS
protocol or in the ‘inbound’ Xon/Xoff method. Both may be controlled
by fully/partially automatic methods or by interrupt generation.
In the 68K mode data is written to the registers on the rise of CEN or
the fall of DACKN, whichever one occurs first. Data on a read cycle
will become valid with respect to the fall of CEN. It will always be
valid at the fall of DACKN.
IACKN Cycle, Update CIR
When the host CPU responds to the interrupt, it will usually assert
the IACKN signal low. This will cause the intelligent interrupt system
of the DUART to generate an IACKN cycle in which the condition of
the interrupting source is determined. When IACKN asserts, the last
valid of the interrupt arbitration cycle is captured in the CIR. The
value captured presents all of the important details of the highest
priority interrupt at the moment the IACKN (or the ‘Update CIR’
command) was asserted. Due to system interrupt latency the
interrupt condition captured by the CIR may not be the condition that
caused the initial assertion of the interrupt.
Test Modes and Software
Four test modes are provided to verify UART function and processor
interface integrity. The first three are Auto echo, Local Loop Back,
and Remote Loop Back. Through local loop back the software
developer may verify all of the interrupt, flow control; the hardware
designer verify all of the timing and pin connections. This information
is obtained without any recourse to external test equipment, logic
analyzers or terminals.
The fourth, Receiver Error Loop back verification, employs a method
of automatic checking (accounting for transmission delays) of the
transmitted data to as echoed back through the remote receiver.
Errors generate interrupt and status events.
The Dual UART will respond to the IACKN cycle with an interrupt
vector. The interrupt vector may be a fixed value, the content of the
Interrupt Vector Register, or when ‘Interrupt Vector Modification’ is
enabled via ICR, it may contain codes for the interrupt type and/or
interrupting channel. This allows the interrupt vector to steer the
interrupt service directly to the proper service routine. The interrupt
value captured in the CIR remains until another IACKN or ‘Update
CIR’ command is given to the DUART. The interrupting channel and
interrupt type fields of the CIR set the current ‘interrupt context’ of
the DUART. The channel component of the interrupt context allows
the use of Global Interrupt Information registers that appear at fixed
positions in the register address map. For example, a read of the
Global RxFIFO will read the channel B RxFIFO if the CIR interrupt
context is channel B receiver. At another time read of the GRxFIFO
may read the channel A RxFIFO (CIR holds a channel A receiver
interrupt) and so on. Global registers exist to facilitate qualifying the
DETAILED DESCRIPTIONS
NOTE: For the convenience of the reader some paragraphs
of the following sections are repeated in descriptions of
closely linked functions described in other sections.
Bus Interface
The bus interface operates in two modes selected by the I/M pin. If
this pin is HIGH the signals DACKN signal is not generated or used
and data flow to and from the chip is controlled by the state the
CEN, RDN, WRN pin combination. If the I/M pin is tied low the data
is written to the device when the DACKN pin is asserted low by the
DUART. Read data is presented by a delay from CEN active.
The Host interface is comprised of the signal pins CEN, WRN RDN,
(or R/WN) IACKN, DACKN, IRQN, 6 address pins and 8 three-state
2005 Nov 01
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Whenever the these timers are selected via the receiver or
transmitter Clock Select register their output will be configured as a
16x clock for the respective receiver or transmitter. Therefore one
needs to program the timers to generate a clock 16 times faster than
the data rate. The formula for calculating ’n’, the number loaded to
the CTPU and CTPL registers, based on a particular input clock
frequency is shown below.
interrupt parameters and for writing to and reading from FIFOs
without explicitly addressing them.
The CIR will load with 0x00 if IACKN or Update CIR is asserted
when the arbitration circuit is NOT asserting an interrupt. In this
condition there is no arbitration value that exceeds the threshold
value. When Interrupt vector modification is active in this situation
the interrupt vector bits associated with the CIR will all be zero. A
zero type field indicates nothing with in the DUART is requiring
processor service.
For the timer mode the formula is as follows:
n+
NOTE: IACKN is essentially a special read action where the value of
the interrupt vector is presented to the data bus.
C/T clock input frequency
16
(desired baud rate))
(If the pulse mode is selected, then ‘2’ in the divisor should be ‘1’.
This doubles the C/T output speeds for any given input clock.)
Timing Circuit
Crystal Oscillator
The crystal oscillator operates directly from a crystal, tuned between
7.0 MHz and 16.2 MHz connected across the X1/Sclk and X2 inputs
with a minimum of external components. BRG values listed for the
clock select registers correspond to a 14.7456 MHz crystal
frequency. Use of different frequencies will change the ‘standard’
baud rates by precisely the ratio of 14.7456 MHz to the different
crystal frequency.
NOTE: ‘n’ may assume a value of 1. In previous Philips data
communications controllers this value was not allowed. The
Counter/Timer Clock Select Register (CTCS) controls the
Counter/Timer input frequency.
The frequency generated from the above formula will be at a rate 16
times faster than the desired baud rate. The transmitter and receiver
state machines include divide by 16 circuits, which provide the final
frequency and provide various timing edges used in the qualifying
the serial data bit stream. Often this division will result in a
non-integer value: 26.3 for example. One may only program integer
numbers to a digital divider. There for 26 would be chosen. If 26.7
were the result of the division then 27 would be chosen. This gives a
baud rate error of 0.3/26.3 or 0.3/26.7 that yields a percentage error
of 1.14% or 1.12% respectively, well within the ability of the
asynchronous mode of operation. Higher input frequency to the
counter reduces the error effect of the fractional division.
An external clock up to 50 MHz frequency range may be connected
to X1/Sclk pin. If an external clock is used instead of a crystal,
X1/Sclk must be driven and X2 left floating or driving a load of not
more than 2 CMOS or TTL equivalents. The X1/Sclk clock serves as
the basic timing reference for the baud rate generator (BRG) and is
available to the programmable BRG (PBRG), counter-timers, control
logic and the UART receivers and transmitters.
Baud Rate Generator BRG
The baud rate generator operates from the oscillator or external
X1/Sclk clock input and generates 27 commonly used data
communications baud rates (including MIDI) ranging from 50 baud
to 921.6K baud. These common rates may be increased (up to
3000K baud) when faster clocks are used on the X1/Sclk clock
input. (See Receiver and Transmitter Clock Select Register
descriptions.) All of these are available simultaneously for use by
any receiver or transmitter. The clock outputs from the BRG are at
16X the actual baud rate.
One should be cautious about the assumed benign effects of small
errors since the other receiver or transmitter with which one is
communicating may also have a small error in the precise baud rate.
In a ‘clean’ communications environment using one start bit, eight
data bits and one stop bit the total difference allowed between the
transmitter and receiver frequency is approximately 4.6%. Less than
eight data bits will increase this percentage.
Programmable Baud Rate Generators. PBRG
Two PBRG Counters (Used only for random baud rate generation)
The two PBRG Timers are programmable 16 bit dividers that are
used for generating miscellaneous clocks. These clocks may be
used by any or all of the receivers and transmitters in the SC28L202
or output to the general purpose I/O pins.
Please see counter timer description for a description of the
frequency error that the asynchronous protocol may tolerate.
Depending on character length it varies from 4.1% to 6.7%.
Counter-Timer
The two Counter/Timers are programmable 16 bit dividers that are
used for generating miscellaneous clocks or generating timeout
periods or counting characters received by the receivers. Interrupts
may be generated any time the counter passes through 0x00. These
clocks may be used by any or all of the receivers and transmitters in
the DUART or may be directed to an I/O pin for miscellaneous use.
Counter/Timer programming
The counter timer is a 16-bit programmable divider that operates in
one of four modes: character count, counter, timer, and time out.
Character count counts characters. The timer mode generates a
square wave. In the counter mode it generates a time delay. In the
time out mode it monitors the time between received characters.
The C/T uses the numbers loaded into the Counter/Timer Lower
Register (CTPL) and the Counter/Timer Upper Register (CTPU) as
its divisor. The counter timer is controlled with six commands:
Start/Stop C/T, Read/Write Counter/Timer lower register and
Read/Write Counter/Timer upper register. These commands have
slight differences depending on the mode of operation. Please see
the detail of the commands under the CTPL/CTPU Register
descriptions.
2005 Nov 01
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Each timer unit has eight different clock sources available to it as
described in the PBRG clock source Register. Note that the timer
run and stop controls are also contained in this register. The PBRG
counters generate a symmetrical square wave whose half period is
equal in time to the division of the selected PBRG Timer clock
source by the number loaded to the PBRGPU and PBRGPL Preset
Registers. Thus, the output frequency will be the clock source
frequency divided by twice the 16 bit value loaded to these registers.
This is the result of counting down once for the high portion of the
output wave and once for the low portion.
Whenever the these timers are selected via the receiver or
transmitter Clock Select register their output will be configured as a
16x clock for the respective receiver or transmitter. Therefore one
needs to program the timers to generate a clock 16 times faster than
the data rate. The formula for calculating ’n’, the number loaded to
the PBRGPL and PBRGPU registers, is the same as shown above.
7
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
can not be active without TxRDY also being active. These two bits
will go active upon initial enabling of the transmitter.
I/O Ports
Eight I/O ports are ‘loosely’ provided for each channel. They may be
programmed to be inputs or outputs. The input circuits are always
active whether programmed as and input or an output. In general a
2-bit code in the I/OPCR (I/O Port Control Register) controls what
function these pins will present. All I/O ports default to high
impedance input state on power up. All 16 I/O pins have a small
pull-up ‘resistor’ that provides approximately 5 µA current.
The transmitter status bits are normally cleared by servicing the
interrupt condition they represent or by Tx reset or Tx disable
commands.
Transmission resumes and the Tx Idle bit is cleared when the CPU
loads at least one new character into the TxFIFO. The TxRDY will
not extinguish until the TxFIFO is completely full. The TxRDY bit will
always be active when the transmitter is enabled and there is at
lease one open position in the TxFIFO.
When calling software written for legacy two channel UARTs
manufactured by Philips (Signetics), be sure I/O pins are set to
input where the legacy software expected an input. Declare I/O
pins as output where the legacy software expected an output.
The transmitter is disabled by a hardware reset, a transmitter reset
in the command register or by the transmitter disable bit also in the
command register (CR). The transmitter must be explicitly enabled
via the CR before transmission can begin. Note that characters
cannot be loaded into the TxFIFO while the transmitter is disabled,
hence it is necessary to enable the transmitter and then load the
TxFIFO. It is not possible to load the TxFIFO and then enable the
transmission.
Input Characteristics of the I/O ports
Eight I/O pins are provided for each channel. These pins are
configured individually to be inputs or outputs. As inputs they may
be used to bring external data to the bus, as clocks for internal
functions or external control signals. Each I/O pin has a ‘Change of
State’ detector. The change detectors are used to signal a change in
the signal level at the pin (Either 0-to-1 or 1-to-0 transitions). The
level change on these pins must be stable for 25 to 50 µs (two
edges of the internally generated 38.4 kHz baud rate clock) before
the detectors will signal a valid change. These are typically used for
interface signals from modems to the DUART and from there to the
host.
Output Port of the I/O ports
The OPR, I/OPCR, MR, and CR registers may control the I/O pins
when configured as outputs. (For the control in the lower 16 position
address space the control register is the OPCR) Via appropriate
programming the pins of the output port may be configures as
another parallel port to external circuits, or they may represent
internal conditions of the UART. When this 8-bit port is used as a
general-purpose output port, the output port pins drive inverse logic
levels of the individual bits in the Output Port Register (OPR). The
OPR register is set and reset by writing to the SOPR and ROPR
addresses. (See the description of the SOPR and ROPR registers).
The output pins will drive the same data polarity of the OPR
registers. The I/OPCR (or the OPCR) register conditions these
output pins to be controlled by the OPR or by other signals in the
chip. Output ports are driven high on hardware reset.
Note the difference between transmitter disable and transmitter
reset.
Either hardware or software may cause the reset action. When reset
the transmitter stops transmission immediately. The transmit data
output will be driven high, transmitter status bits set to zero and any
data remaining in the TxFIFO is effectively discarded.
The transmitter disable is controlled by the Tx Enable bit in the
command register. Setting this bit to zero will not stop the transmitter
immediately but will allow it to complete any tasks presently
underway. It is only when the last character in the TxFIFO and its
stop bit(s) have been transmitted that the transmitter will go to its
disabled state. While the transmitter enable/disable bit in the
command register is at zero the TxFIFO will not accept any more
characters and the Tx Idle and TxRDY bits of the status register set
to zero.
Transmission of ‘break’
Transmission of a break character is often needed as a
synchronizing condition in a data stream. The ‘break’ is defined as a
start bit followed by all zero data bits by a zero parity bit (if parity is
enabled) and a zero in the stop bit position. The forgoing is the
minimum time to define a break. The transmitter can be forced to
send a break (continuous low condition) by issuing a start break
command via the CR. Once the break starts, the TxD output
remains low until the host issues a command to ‘stop break’ via the
CR or the transmitter is issued a software or hardware reset. In
normal operation the break is usually much longer than one
character time.
1x and 16x modes, Transmitter
The transmitter clocking has two modes: 16x and 1x. Data is always
sent at the 1x rate. However the logic of the transmitter may be
operated with a clock that is 16 times faster than the data rate or at
the same rate as the data i.e. 1x. All clocks selected internally for
the transmitter (and the receiver) will be 16x clocks. Only when an
external clock is selected may the transmitter logic and state
machine operate in the 1x mode. The 1x or 16x clocking makes little
difference in transmitter operation. (This is not true in the receiver)
In the 16X-clock mode the transmitter will recognize a byte in the
TxFIFO within 1/16 to 2/16-bit time and thus begin transmission of
the start bit. In the 1x mode this delay may be up to 2 bit times.
Transmitter FIFO
The FIFO configuration of the as 28L202 is 256 8-bit words.
Interrupt levels may be set to any level within the FIFO size and may
be set differently for each FIFO. Logic associated with the FIFO
UART Operation
Receiver and Transmitter
The Dual UART has two full duplex asynchronous
receiver/transmitters. The operating frequency for the receiver and
transmitter can be selected independently from the baud rate
generator, the counter, or from an external input. Registers that are
central to basic full-duplex operation are the mode registers (MR0,
MR1 and MR2), the clock select registers (RxCSR and TxCSR), the
command register (CR), the status register (SR), the transmit
holding register (TxFIFO), the receive holding register (RxFIFO),
interrupt status register (ISR) and interrupt mask register (IMR).
MR3 controls the automatic activity or the Xon/Xoff flow control,
Address recognition, multi-drop (‘9-bit’ mode) and general purpose
character recognition. Because MR3 does not exist in legacy
UARTs, these features should be disabled before legacy code is
loaded.
Transmitter Status Bits
The SR (Status Register, one per UART) contains two bits that show
the condition of the transmitter FIFO. These bits are TxRDY and Tx
Idle. TxRDY means the TxFIFO has space available for one or more
bytes; Tx Idle means The TxFIFO is completely empty and the last
stop bit has been completed—the transmitter is underrun. Tx Idle
2005 Nov 01
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
RS-485 method) the meaning of the I/O0 B or I/O1 B signals is ‘all
bytes loaded to the transmitter’s FIFO have been transmitted
including the last stop bit(s). See the MR2(5) description for enabling
this automatic function.
encodes the number of empty positions for presentation to the
interrupt arbitration system. The encoding value is the number of
empty positions. Thus, an empty TxFIFO will bid with the value or
255; when full it will not bid at all; one position empty bids with the
value 0. A Full TxFIFO will not bid since no character is available.
Receiver Operation
Receiver
The receiver accepts serial data on the RxD pin, converts the serial
input to parallel format, checks for start bit, stop bit, parity bit (if any),
framing error or break condition, and presents the assembled
character and its status condition to the CPU via the RxFIFO. Three
status bits are FIFOed with each character received. The RxFIFO is
really 11 bits wide: eight data and 3 status. Unused FIFO bits for
character lengths less than 8 bits are set to zero.
Normally TxFIFO will present a bid to the arbitration system
whenever it has one or more empty positions. The Bits of the
TxFIFO Interrupt Level in the MR0(5:4) allow the user to modify this
characteristic so that bidding will not start until one of four levels
(one or more filled, empty, 16 filled, 240 filled, full) have been
reached. As will be shown later this feature may be used to make
moderate improvements in the interrupt service efficiency. A similar
system exists for the Receiver.
Transmitter
The 28L202 is conditioned to transmit data when the transmitter is
enabled through the command register. The transmitter of the
28L202 indicates to the CPU that it is ready to accept a character by
setting the ISR TxRDY bit in the status register. This condition can
be programmed to generate an interrupt request at I/O4 or IRQN.
When the transmitter is initially enabled the TxRDY and Tx Idle bits
will be set in the status register. When a character is loaded to the
transmit FIFO the Tx Idle bit will be reset. The Tx Idle bit will not set
until the transmit FIFO is empty and the transmit shift register has
finished transmitting the stop bit of the last character written to the
transmit FIFO.
It is important to note that in the asynchronous protocol the receiver
logic considers the entire message to be contained within the start
bit to the stop bit. It is not aware that a message may contain many
characters. The receiver returns to its idle mode at the end of each
stop bit! As described below it immediately begins to search for
another start bit, which is normally, of course, immediately
forthcoming.
1x and 16x mode, Receiver
The receiver operates in one of two modes: 1x and 16x. Of the two,
the 16x is more robust and the preferred mode. Although the 1x
mode may allow a faster data rate is does not provide for the
alignment of the receiver 1x data clock to that of the transmitter. This
strongly implies that the 1x clock of the remote transmitter is
available to the receiver; the two devices are physically close to
each other.
The TxRDY bit is set whenever the transmitter is enabled and the
TxFIFO is not full. Data is transferred from the holding register to
transmit shift register when it is idle or has completed transmission
of the previous character. Characters cannot be loaded into the
TxFIFO while the transmitter is disabled.
The 16x mode operates the receiver logic at a rate 16 times faster
than the 1x data rate. This allows for validation of the start bit length,
the validation of level changes at the receiver serial data input
(RxD), and the validation of the stop bit length. Of most importance
in the 16x mode is the ability of the receiver logic to align the phase
of the internally generated receiver 1x data clock to that of the
received start bit of the remote transmitter. This occurs with an
accuracy of less than 1/16 bit time.
Receiver
The receiver of the 28L202 is conditioned to receive data when
enabled through the command register. The receiver looks for a
High-to-Low (mark-to-space) transition of the start bit on the RxD
input pin. If a transition is detected, the state of the RxD pin is
sampled each 16X clock for 7-1/2 clock periods (16X clock mode) or
at the next rising edge of the bit time clock (1X clock mode). If RxD
is sampled high, (that is the start bit was low less than 7/16 to ½ bit
time) the start bit is judged invalid and the search for another valid
start bit begins immediately. If RxD is still low, a valid start bit is
assumed and the receiver then continues to sample the input at
one-bit time intervals at the theoretical center of the bit. When the
proper number of data bits and parity bit (if used) have been
assembled, and one half-stop bit has been detected the receiver
loads the byte to the FIFO. The least significant bit is received first.
The data is then transferred to the Receive FIFO and the ISR
RxRDY bit in the SR is set to a 1. This condition can be
programmed to generate an interrupt at IRQN or I/O[4:5] for
channels A or B respectively. If the character length is less than 8
bits, the most significant unused bits in the RxFIFO are set to zero.
The transmitter converts the parallel data from the CPU to a serial
bit stream on the TxD output pin. It automatically sends a start bit
followed by the programmed number of data bits, an optional parity
bit, and the programmed number of stop bits. The least significant
bit is sent first. Following the transmission of the stop bits, if a new
character is not available in the TxFIFO, the TxD output remains
High and the Tx Idle bit in the Status Register (SR) will be set to 1.
Transmission resumes and the Tx Idle bit is cleared when the CPU
loads a new character into the TxFIFO.
If the transmitter is disabled, it continues operating until the
character currently being transmitted is completely sent out. The
transmitter can be forced to send a continuous Low condition by
issuing a send break command. The transmitter can be reset
through a software command. If it is reset, operation ceases
immediately and the transmitter must be enabled through the
command register before resuming operation.
If CTS option of hardware flow control is enabled (MR2 [4] = 1), the
CTS input at I/O0 or I/O1 must be Low in order for the character to
be transmitted. The transmitter will check the state of the CTS input
at the beginning of each character transmitted. If it is found to be
High, the transmitter will delay the transmission of any following
characters until the CTS has returned to the low state. CTS going
high during the serialization of a character will not affect that
character.
It is an interesting point of the I/O system inputs being always active
that by enabling transmitter to be sensitive the I/O0 or I/O1 and then
controlling the I/O pin as an out put that one is able to control the
transmitter flow via software control of the I/O pin.
After the stop bit is detected, the receiver will immediately look for
the next start bit. However, if a non-zero character was received with
the stop bit at a zero level (framing error) and RxD remains Low for
at least another one half bit time after the stop bit was sampled, then
The transmitter can also control the RTSN outputs, I/O0 or I/O1 via
MR2 [5]. When this mode of operation is set (often referred to as the
2005 Nov 01
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
NOTE: Precaution must be taken when reading an overrun FIFO.
There will be 256th valid characters in the receiver FIFO. There will
be one character in the receiver shift register. However it will NOT
be known if more than one ‘over-running’ character has been
received since the overrun bit was set. The 257th character received
and read as valid but it will not be known how many characters were
lost between the two characters of the 256th and 257th reads of the
RxFIFO. In the 8-bit mode, the numbers 8 and 9 replace the
numbers 256 and 257 above.
the receiver operates as if a new start bit had been detected. It then
continues assembling the next character.
The error conditions of parity error, framing error, and overrun error
(if any) are written to the SR at the received character boundary.
This is just before the RxRDY status bit is set.
A break condition is detected when RxD is Low for the entire
character including the parity bit, if used, and stop bit. When a break
is found a character consisting of all zeros will be loaded into the
RxFIFO, the received break bit in the SR and the ‘change of break’
bit in the ISR are set to 1 and the receiver ready is set in the SR.
The RxD input must return to high for two (2) clock edges of the
RxC1x clock for the receiver to recognize the end of the break
condition. At the end of the break condition the search for the next
start bit begins.
The ‘Change of break’ means that either a break has been detected
or that the break condition has been cleared. This bit is available in
the ISR. The break change bit being set in the ISR and the received
break bit being set in the SR will signal the beginning of a break. At
the termination of the break condition only the change of break in
the ISR will be set. After the break condition is detected the
termination of the break will only be recognized when the RxD input
has returned to the high state for two successive edges of the 1x
clock; 1/2 to 1 bit time. (see above)
Two edges of the RxC1x clock will usually require a high time of one
RxC1x clock period or 3 RxC1x edges since the clock of the
controller is usually not synchronous to nor in phase with the RxC1x
clock.
Receiver Status Bits
There are five (5) status bits that are evaluated with each byte (or
character) received: received break, framing error, parity error,
overrun error, and change of break. The first three are appended to
each byte and stored in the RxFIFO. The last two are not
necessarily related to the byte being received or a byte that is in the
RxFIFO. They are however developed by the receiver state
machine.
The receiver is disabled by reset or via CR commands. A disabled
receiver will not interrupt the host CPU under any circumstance in
the normal mode of operation. If the receiver is in the multi-drop or
special mode, it will be partially enabled and thus may cause an
interrupt. Refer to section on Wake-Up and the register description
for MR1 for more information.
Receiver FIFO
The receiver buffer memory is a 256 byte FIFO with three status bits
appended to each data byte. (The FIFO is then 256 11-bit ‘words’).
The receiver state machine gathers the bits from the receiver shift
register and the status bits from the receiver logic and writes the
assembled byte and status bits to the RxFIFO shortly after the stop
bit has been sampled. Logic associated with the FIFO encodes the
number of filled positions for presentation to the interrupt arbitration
system. The encoding is always the number of filled positions. Thus,
a full RxFIFO will bid with the value of 255 and the Status Register
RxFULL bit is set. When empty it will not bit at all. One position
occupied bids with the value 1. An empty FIFO will not bid since no
character is available.
The receiver status bits are normally cleared by servicing the
interrupt condition they represent or by Rx reset or Rx disable
commands or the several error reset commands in the Command
Register (CR).
The ‘received break’ will always be associated with a zero byte in
the RxFIFO. It means that zero character was a break character and
not a zero data byte. The reception of a break condition will always
set the ‘change of break’ (see below) status bit in the Interrupt
Status Register (ISR).
The Change of break condition is reset by a reset error status
command in the command register
Normally RxFIFO will present a bid to the arbitration system
whenever it has one or more filled positions. The bits of the RxFIFO
Interrupt Offset Level (RxFIL) or the bits of the MR2(3:2) allow the
user to modify this characteristic so that bidding will not start until
one of four levels (one or more filled, 64 filled, 192 filled, full) have
been reached. As will be shown later this feature may be used to
make slight improvements in the interrupt service efficiency. A
similar system exists in the transmitter.
RxFIFO Status Bits. Status reporting modes
This description applies to the upper three bits in the ‘Status
Register’. These three bits are not ‘in the status register’; they are
part of the RxFIFO. The three status bits at the output of the RxFIFO
are presented as the upper three bits of the status register included
in each UART.
A framing error occurs when a non-zero character was seen and
that character has a zero in the stop bit position.
The parity error indicates that the receiver-generated parity was not
the same as that sent by the transmitter.
The framing, parity and received break status bits are reset when
the associated data byte is read from the RxFIFO since these ‘error’
conditions are attached to the byte that has the error
The overrun error occurs when the RxFIFO is full, the receiver shift
register is full, and another start bit is detected. At this moment the
receiver has 257 valid characters and the start bit of the 258th has
been seen. At this point the host has approximately 6/16 bit time to
read a byte from the RxFIFO or the overrun condition will be set.
The 258th character then overruns the 257th and the 258th the 259th
and so on until an open position in the RxFIFO is seen. (‘seen’
meaning at least one byte was read from the RxFIFO.)
The error status of a character, as reported by a read of the SR
(status register upper three bits) can be provided in two ways, as
programmed by the error mode control bit in the mode register:
‘Character mode’ or the ‘Block Mode’. The block mode may be
further modified (via a CR command) to set the status bits as the
characters enter the FIFO or as they are read from the FIFO.
Overrun is cleared by a use of the ‘error reset’ command in the
command register.
In the ‘character’ mode, status is provided on a character by
character basis as the characters are read from the RxFIFO: the
‘status’ applies only to the character at the output of the
RxFIFO—The next character to be read.
The fundamental meaning of the overrun is that data has been lost.
Data in the RxFIFO remains valid. The receiver will begin placing
characters in the RxFIFO as soon as a position becomes vacant.
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Dual UART
SC28L202
enable itself to receive the following data stream. Upon receipt of an
address not its own it would then disable itself. As descried below
appropriate status bits are available to describe the operation.
Again, for this mode an ‘address byte’ is a byte that has the bit in the
parity position set to logical 1.
In the ‘block’ mode (on entry) the status provided in the SR for these
three bits is the logical OR of the status for all characters coming to
the input of the RxFIFO since the last reset error command was
issued. In this mode each of the status bits stored in the RxFIFO are
passed through a latch as they are sequentially written to the
receiver FIFO. If any of the characters has an error bit set that latch
will set and remain set until it is reset with a ‘receiver reset’ issued
from the command register or a chip reset is issued. The purpose of
this mode is indicating an error in the data block as opposed to an
error in a character. This mode improves receiver service efficiency.
In modern systems with low error rates, it is more efficient to ask for
retransmit of a block error data than to analyze it on a byte by byte
system.
The use of the multi-drop mode usually implies a ‘master and slave’
configuration of the several UART stations so programmed. The
software control should allow time for the slave stations to respond
to the receipt of an address bit. Often a reply from the addressed
station is expected to confirm the receipt of the address. Please see
control the automatic features of the address recognition in
MR3[1:0].
Enabling the Wake Up mode
(This mode is variously referred to as ‘9-bit’ or ‘Multi-drop’.)
The above paragraph describes the block mode activity as the data
is entered to the RxFIFO. Normally the status would be read only
once—at the beginning of the service to the receiver interrupt. If an
error is not set then the entire amount of data in the RxFIFO would
be read without any more reading if the receiver status. This
effectively doubles the efficiency of reading the receiver RxFIFO.
This mode is selected by programming bits MR1 [4:3] (the parity
bits) to ’11’. The wake up feature has four modes of operation: one
strictly under processor control and three automatic. These modes
are controlled by bits 6, 1, 0 in the MR3 register. Bit 6 controls the
loading of the address byte to the RxFIFO and MR3[1:0] determines
the sub mode as shown in the following list.
The use of the block mode on Exit passes the data and error
conditions as the RxFIFO is read. Here the final read of the status
register would be after the last byte was read from the RxFIFO. This
delays the knowledge of an error condition until after the data has
been read.
MR3[1:0] = 00 Normal Wake Up Mode (default) which is the same
as previous DUARTs and is therefore controlled by the processor.
The Host controls operation via interrupts it receives and commands
it writes to the DUART command registers (CR).
Normal Wake up (The default configuration)
The enabling of the wake-up mode executes a partial enabling of the
receiver state machine. Even though the receiver has been reset the
wake up mode will over ride the disable and reset condition.
The latch used in the block mode to indicate ‘problem data’ is
usually set as the characters are read out of the RxFIFO. Via a
command in the CR the latch may be configured to set as error
characters are loaded to the RxFIFO. This gives the advantage of
indicating ‘problem data’ up to 256 (or the FIFO size) characters
earlier.
In the default (mode ‘00’ above and the least efficient) configuration
for this mode of operation, a ’master’ station transmits an address
character followed by data characters for the addressed ’slave’
station. The slave stations, whose receivers are normally disabled
(not reset), examine the received data stream. Upon recognition of
its address bit (this is the parity bit redefined to indicate the
associated byte is an address bye – not the address itself)
interrupts the CPU (by setting RxRDY). The CPU (host) compares
the received address to its station address and enables the receiver
if it wishes to receive the subsequent data characters. Upon receipt
of another address character, the CPU may disable the receiver to
initiate the process again.
In either mode, reading the SR does not affect the RxFIFO. The
RxFIFO address is advanced only when the RxFIFO is read.
Therefore, the SR should be read prior to reading the corresponding
data character.
If the RxFIFO is full when a new character is received, the character
is held in the receiver shift register until a position is available in the
RxFIFO. At this time there are 257 valid characters in the RxFIFO. If
an additional character is received while this state exists, the
contents of the RxFIFO are not affected: the character previously in
the shift register is lost and the overrun error status bit, SR [4], will
be set upon receipt of the start bit of the new (overrunning)
character.
Wake Up Mode (Also the ‘9-bit’, ‘multi-drop’, ‘party; line’ or Special
mode)
The SC28L202 provides four modes of this common asynchronous
‘party line’ protocol where the parity bit is used to indicate that a byte
is address data or information data. Three automatic modes and the
default Host operated mode are provided. The automatic mode has
several sub modes (see below). In the full automatic the internal
state machine devoted to this function will handle all operations
associated with address recognition, data handling, receiver enables
and disables. In both modes the meaning of the parity bit is
changed. It is often referred to as the A/D bit or the address/data
bit—sometimes the ‘9th’ bit. It is used to indicate whether the byte
presently in the receiver shift register is an ‘address’ byte or a ‘data’
byte. A ‘1’ usually means address, a ‘0’ data.
A transmitted character consists of a start bit; the programmed
number of data bits, an address/data (A/D) bit and the programmed
number of stop bits. The CPU selects the polarity of the transmitted
A/D bit by programming bit MR1 [2]. MR1 [2] = 0 transmits a zero in
the A/D bit position which identifies the corresponding data bits as
data. MR1 [2] = 1 transmits a one in the A/D bit position which
identifies the corresponding data bits as an address. The CPU
should program the mode register prior to loading the corresponding
data bytes into the TxFIFO.
While in this mode, the receiver continuously looks at the received
data stream, whether it is enabled or disabled. If disabled, it sets the
RxRDY status bit and loads the character into the RxFIFO if the
received A/D bit is a one, but discards the received character if the
received A/D bit is a zero. If the receiver is enabled, all received
characters are transferred to the CPU via the RxFIFO. In either case
when the address character is recognized the data bits are loaded
into the data FIFO while the A/D bit is loaded into the status FIFO
position normally used for parity error (SR [5]). Framing error,
overrun error, and break detect operate normally whether or not the
receiver is enabled. When the automatic modes are in operation the
loading of the address character to the FIFO is controlled by the
MR0 (6) bit.
Its purpose is to allow several receivers connected to the same data
source to be individually addressed. Of course addressing could be
by group also. Normally the ‘Master’ would send an address byte to
all receivers ‘listening’. The remote receiver will be ‘looking’ at the
data stream for its address. Upon recognition of its address it will
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Product data sheet
Dual UART
SC28L202
This mode can also be used to indicate when the serial line has
been marking for longer than the programmed time limit. In this
case, the CPU has read all of the characters from the FIFO, but the
last character received has started the count. If there is no new data
during the programmed time interval, the counter ready bit will get
set, and an interrupt can be generated.
The several automatic controls. These modes are concerned with
the recognition of the address character itself
• MR3 [1:0] = 01 Auto wake. Enable receiver on address
recognition for this station. Upon recognition of its assigned
address the local receiver will be enabled by the character
recognition state machine and normal receiver communications
with the host will be established.
Writing the appropriate command to the command register enables
the time-out mode. Writing an ‘Ax’ to CR A or CR B will invoke the
time-out mode for that channel. Writing a 0xCx to CR A or CR B will
disable the time-out mode. CTPU and CTPL should be loaded with a
count-down value that, with the selected clock, will generate a time
period greater than the normal receive character period. The
time-out mode disables the regular START/STOP Counter
commands and puts the C/T into counter mode under the control of
the received data stream. Each time a received character is
transferred from the shift register to the RxFIFO, the C/T is stopped
after 1 C/T clock, reloaded with the value in CTPU and CTPL and
then restarted on the next C/T clock. If the C/T is allowed to end the
count before a new character has been received, the counter ready
bit, ISR [3], will be set. If IMR [3] is set, interrupt arbitration for the
C/T will begin. Invoking the ‘Set Time-out Mode On’ command, CRx
= ‘Ax’, clears the counter ready bit and stop the counter until the
next character is received.
• MR3 [1:0] = 10 Auto Doze. Disable receiver on address
recognition, not for this station. Upon recognition of an address
character that is not its own, in the Auto Doze mode, the receiver
will be disabled by the character recognition state machine and
the address just received either discarded or loaded to the
RxFIFO depending on the programming of MR0 [6].
• MR3 [1:0] = 11 Auto wake and doze. Both modes described
above. The programming of MR3 [1:0] to 11 will enable both the
auto wake and auto doze features.
The enabling of the wake-up mode executes a partial enabling of the
receiver state machine. Even though the receiver has been reset the
wake up mode will over ride the disable and reset conditions.
Receiver Reset and Disable
Receiver disable stops the receiver immediately – data being
assembled in the receiver shift register is lost. Data and status in the
FIFO is preserved and may be read. A re-enable of the receiver
after a disable will cause the receiver to begin assembling
characters at the next start bit detected.
Exiting the time mode will clear the counter ready bit.
Arbitrating Interrupt Structure
(NOTE: The advantages and intelligence of this system may be
completely defeated by merely setting the arbitration value in the
ICR to 0x00 and not using the CIR. One would then rely on
traditional interrupt service by searching and testing various status
registers on the assertion of the IRQN.)
Receiver reset will discard the present shift register data, reset the
receiver ready bit (RxRDY), clear the status of the byte at the top of
the FIFO and re-align the FIFO read/write pointers. This effectively
‘clears’ the receiver FIFO although the FIFO data is not altered.
Receiver Watchdog Timer
A ‘watchdog timer’ is associated with each receiver. Its interrupt is
enabled by the ‘watchdog’ bits of the ‘Watch Dog, Character
Address, and X enable’ register (WCXER). The purpose of this timer
is to alert the control processor that characters are in the RxFIFO
which have not been read and/or the data stream has stopped. This
situation may occur at the end of a transmission when the last few
characters received are not sufficient to cause an interrupt. This
counter times out after 64 bit times. It is reset each time a read of
the RxFIFO is executed.
Receiver Time-out Mode
In addition to the watch dog timer described in the receiver section,
the counter/timer may be used for a similar function. Its
programmability, of course, allows much greater precision of timeout
intervals.
The interrupt system determines when an interrupt should be
asserted thorough an arbitration (or bidding) system. This arbitration
is exercised over the several systems within the DUART that may
generate an interrupt. These will be referred to as ‘interrupt sources’.
There are 18 in all and may of those have several sub-levels. In
general the arbitration is based on the fill level of the receiver FIFO
or the empty level of the transmitter FIFO. The FIFO levels are
encoded into an 8-bit number, which is concatenated to the channel
number and source identification code. All of this is compared (via
the bidding or arbitration process) to a user defined ‘threshold’.
Whenever a source exceeds the numerical value of the threshold
the interrupt will be generated.
Interrupt sources that do not have a FIFO are each provided with a
‘programmable field’ that will determine their importance in the
arbitration and type identification process. (See Table 1 below)
The time-out mode uses the received data stream to control the
counter. Each time a received character is transferred from the shift
register to the RxFIFO, the counter is restarted. If a new character is
not received before the counter reaches zero count, the counter
ready bit is set, and an interrupt can be generated. This mode can
be used to indicate when data has been left in the RxFIFO for more
than the programmed time limit. Otherwise, if the receiver has been
programmed to interrupt the CPU when the receive FIFO is full, and
the message ends before the FIFO is full, the CPU may not know
there is data left in the FIFO. The CTPU and CTPL value would be
programmed for just over one character time, so that the CPU would
be interrupted as soon as it has stopped receiving continuous data.
2005 Nov 01
At the time of interrupt acknowledge (IACKN) the source which has
the highest bid (not necessarily the source that caused the interrupt
to be generated) will be captured in a ‘Current Interrupt Register’
(CIR). This register will contain the complete definition of the
interrupting source: channel, types of interrupt (receiver, transmitter,
change of state, etc.) and FIFO fill level. The value of the bits in the
CIR are used to drive the interrupt vector and global registers such
that controlling processor may be steered directly to the proper
service routine. A single read operation to the CIR provides all the
information needed to qualify and quantify the most common
interrupt sources.
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
full. This will prevent its relatively high priority from winning the
arbitration process at low fill levels. A high threshold level could
accomplish the same thing, but may also mask out low priority
interrupt sources that must be serviced. Note that for fast channels
and/or long interrupt latency times using this feature should be used
with caution since it reduces the time the host CPU has to respond
to the interrupt request before receiver overrun occurs.
The interrupt sources for each channel are listed below.
• Receiver without error
• Receiver with error for each channel
• Receiver Watch Dog Time-out Event
• Transmitter
• Change in break received status per channel
• Rx loop back error
• Change of state on channel input pins
• Xon/Xoff character recognition
• Counter-Timer
• Address character recognition
• No interrupt active (very useful in polled service and as a test
Setting interrupt priorities
The bid or interrupt number presented to the interrupt arbiter is
composed of character counts, channel codes, fixed and
programmable bit fields. The interrupt values are generated for
various interrupt sources as shown in Table 1. The value
represented by the bits 11 to 4 in Table 1 are compared against the
value represented by the ‘Threshold. The ‘Threshold’, bits 10 to 0 of
the ICR (Interrupt Control Register), is aligned such that bit 0 of the
threshold is compared to bit 1 of the interrupt value generated by
any of the sources. Whenever the value of the interrupt source is
greater than the threshold the interrupt will be generated.
value to terminate interrupt service)
The channel number arbitrates only against other channels. The
threshold is not used for the channel arbitration. This results in
channel B having the highest arbitration number. The decreasing
order is B to A. If all other parts of an arbitration cycle are equal then
the channel number will determine which channel will dominate in
the arbitration process.
Transmit FIFO empty level and Receiver FIFO fill levels are unique
for each channel and may be set at any level.
Associated with the interrupt system are the interrupt mask register
(IMR) and the interrupt status register (ISR) resident in each UART.
Programming of the IMR selects which of the above sources may
enter the arbitration process. The IMR enables the interrupt. Only
the bidders in the ISR whose associated bit in the IMR is set to one
(1) will be permitted to enter the arbitration process. The ISR can be
read by the host CPU to determine all currently active interrupting
conditions. For convenience of reading the ISR the MR1 (6) bit,
when set, allows the reading of the ISR masked by the bits of the
IMR.
Enabling and Activating Interrupt sources
An interrupt source becomes enabled when writing a one to the
proper Interrupt Mask Register bit (IMR) activates its interrupt
capability. An interrupt source can never generate an IRQN or have
its ‘bid’ or interrupt number appear in the CIR unless the source has
been enabled by the appropriate bit in an IMR.
Note several characteristics of Table 1 in bits 4:1. These bits contain
the identification of the bidding source as indicated below:
• x001 Receiver without error
• x101 Receiver with error (errors are: parity, framing and overrun.
Break is not considered an error.
An interrupt source is active if it is presenting its bid to the interrupt
arbiter for evaluation. Most sources have simple activation
requirements. The watch-dog timer, break received, Xon/Xoff or
Address Recognition and change of state interrupts become active
when the associated events occur and the arbitration value
generated thereby exceeds the threshold value programmed in the
ICR (Interrupt Control Register).
• x100 Receiver Watch Dog
• x010 Transmitter
• 1110 Change of Break
• 1111 Rx Loop Back Error
• 0110 Change of State on I/O Ports
• 0111 Xon/Xoff Event
• 1000 Counter timer
• 1011 Address Recognition
• 0000 No interrupt source active
The transmitter and receiver functions have additional controls to
modify the condition upon which the initiation of interrupt ‘bidding’
begins: the TxINT and RxINT fields of the MR0 and MR2 registers.
These fields can be used to start bidding or arbitration when the
RxFIFO is not empty, 50% full, 75% full or 100% full. For the
transmitter it is not full, 50% empty, 75% empty and empty.
The codes form bits 4:1 drive part of the interrupt vector modification
and the Global Interrupt Type Register. The codes are unique to
each source type and identify them completely. The channel
numbering progresses from ‘A’ to ‘B’ as the binary numbers 0 to 1
and identify the interrupting channel uniquely. As the channels
arbitrate ‘B’ will have the highest bidding value and ‘A’ the lowest.
Example: To increase the probability of transferring the contents of a
nearly full RxFIFO, do not allow it to start bidding until 50% or 75%
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Dual UART
SC28L202
Table 1. Interrupt Values
Type
Bit 11:4
Bit 3
Bit 2
Bit 1
Bit 0
Receiver w/o error
RxFIFO filled Byte Count
0
0
1
Channel No.
Receiver w/ error
RxFIFO filled Byte Count
1
0
1
Channel No.
Receiver Watch-dog
RxFIFO filled Byte Count
1
0
0
Channel No.
Transmitter
TxFIFO empty Byte Count
0
1
0
Channel No.
Change of Break
Programmed Field
1
1
1
0
Channel No.
Rx Loop Back Error
Programmed Field
1
1
1
1
Channel No.
Change of State
Programmed Field
0
1
1
0
Port 0 or 1
Xon/Xoff
Programmed Field
0
1
1
1
Channel No.
Counter timer
Programmed Field
1
0
0
0
Counter 0 or 1
Address Recognition
Programmed Field
1
0
1
1
Channel No.
No interrupt
0
0
0
0
0
Threshold
Bits 7:0 of Interrupt Control Register (ICR)
0
0
0
0
weather report or stock market ‘ticker-tape’ report needs breaks in
the data so that a receiver knows where the data starts. Once start
of the break is detected it is important to reset the ‘change of break’
interrupt so that this bit can signal the condition of the break ending.
This is signaled by the ‘L202 the setting another change of break
event in the ISR. Since it is assumed the data will be starting very
soon after the end of break it is important to give the change of
break condition a high priority. This may be accomplished by setting
the arbitration value for the ‘change of break’ to a high value. The
value in the ‘change of break programmable field’ in Table 1 would
be 0x7F.
IACKN Cycle, Update CIR
When the host CPU responds to the interrupt, it will usually assert
the IACKN signal low. This will cause the DUART to generate an
IACKN cycle in which the condition of the interrupting device is
determined. When IACKN asserts, the last valid interrupt number is
captured in the CIR. The value captured presents most of the
important details of the highest priority interrupt at the moment the
IACKN (or the ‘Update CIR’ command) was asserted.
Interrupt Arbitration and IRQN generation
Interrupt arbitration is the process used to determine that an
interrupt request should be presented to the host. The arbitration is
carried out between the ‘Interrupt Threshold’ and the ‘sources’
whose interrupt bidding is enabled by the IMR. The interrupt
threshold is part of the ICR (Interrupt Control Register) and is a
value programmed by the user. The ‘sources’ present a value to the
interrupt arbiter. That value is derived from four fields: the channel
number, type of interrupts source, FIFO fill level, and a
programmable value. The interrupt request (IRQN) will be asserted
only when one or more of these values exceeds the threshold value
in the interrupt control register will.
Following assertion of the IRQN the host will either assert IACKN
(Interrupt Acknowledge) or will use the command to ‘Update the
CIR’. At the time either action is taken the CIR will capture the value
of the source that is prevailing in the arbitration process. (Call this
value the winning bid).
The Sclk drives the arbitration process. It evaluates the 12 bits of
the arbitration bus at ½ the Sclk rate developing a value for the CIR
every two Sclk cycles. New arbitration values presented to the
arbitration block during an arbitration cycle will be evaluated in the
next arbitration cycle.
The Dual UART will respond to the IACKN cycle with an interrupt
vector. The interrupt vector may be a fixed value, the content of the
Interrupt Vector Register, or when ‘Interrupt Vector Modification’ is
enabled via ICR, it may contain codes for the interrupt type and/or
interrupting channel. This allows the interrupt vector to steer the
interrupt service directly to the proper service routine. The interrupt
value captured in the CIR remains until another IACKN cycle occurs
or until an ‘Update CIR’ command is given to the DUART. The
interrupting channel and interrupt type fields of the CIR set the
current ‘interrupt context’ of the DUART. The channel component of
the interrupt context allows the use of Global Interrupt Information
registers that appear at fixed positions in the register address map.
For example, a read of the Global RxFIFO will read the channel B
RxFIFO if the CIR interrupt context is channel B receiver. At another
time read of the GRxFIFO may read the channel A RxFIFO (CIR
holds a channel A receiver interrupt) and so on. Global registers
exist to facilitate qualifying the interrupt parameters and for writing to
and reading from FIFOs without explicitly addressing them.
For sources other than receiver and transmitters the user may set
the high order bits of an interrupt source’s bid value, thus tailoring
the relative priority of the interrupt sources. The fill level of their
respective FIFOs controls the priority of the receivers and
transmitters. The more filled spaces in the RxFIFO the higher the bid
value; the more empty spaces in the TxFIFO the higher its priority.
Channels whose programmable high order bits are set will be given
interrupt priority higher than those with zeros in their high order bits,
thus allowing increased flexibility. The transmitter and receiver bid
values contain the character counts of the associated FIFOs as high
order bits in the bid value. Thus, as a receiver’s RxFIFO fills, it bids
with a progressively higher priority for interrupt service. Similarly, as
empty space in a transmitter’s TxFIFO increases, its interrupt
arbitration priority increases.
The CIR will load with x’00 if IACKN or Update CIR is asserted when
the arbitration circuit is NOT asserting an interrupt. In this condition
there is no arbitration value that exceeds the threshold value. When
Interrupt vector modification is active in this situation the interrupt
vector bits associated with the CIR will all be zero.
The programmable fields allow the software to adjust the authority or
value of the bid for those devices not having a FIFO.
For example: The break condition is sometimes used to signal a
starting point in a continuous stream of data. A Continuous running
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
operations specific to ‘Multi-drop’ address recognition or in-band
Xon/Xoff flow control.
Global Registers
The ‘Global Registers’, 10 in all, are driven by the interrupt system.
They are defined by the content of the CIR (Current Interrupt
Register) as a result of an interrupt arbitration. In other words they
are indirect registers pointed to by the content of the CIR. The list of
global register follows:
• GIBCR
• GICR
• GITR
• GRxFIFO
• GTxFIFO
Character recognition system continually examines the incoming
data stream. Upon the recognition of a character bits appropriate for
the character recognized are set in the Xon/Xoff Interrupt Status
Register (XISR) and in the Interrupt Status Register (ISR). The
setting of these bit(s) will initiate any of the automatic sequences or
and/or an interrupt that may have enabled via the MR3 register.
The byte count of the interrupting FIFO
Channel number of the interrupting channel
NOTE: Reading the XISR Clears the status bits associated with the
recognition.
Type identification of interrupting channel
Pointer to the interrupting receiver FIFO
The characters of the recognition system are fully programmable.
The Xon/Xoff characters will be set to the standard characters if the
hardware or software reset is used.
Pointer to the interrupting transmitter FIFO
A read of the GRxFIFO will give the content of the RxFIFO that
presently has the highest bid value. The purpose of this system is to
enhance the efficiency of the interrupt system. The global registers
and the CIR update procedure are further described in the Interrupt
Arbitration system
Polling, (Normal and using the CIR)
The ‘arbitrating interrupt system’ will reduce the polling overhead to
only two bus cycles. It only requires an update CIR command and a
CIR read to find if service is needed, and if needed to show what
needs to be serviced.
The character recognition circuits are basically designed to provide
general-purpose character recognition. Additional control logic has
been added to allow for Xon/Xoff flow control and for recognition of
the address character in the multi-drop or ‘wake-up’ mode. This logic
also allows for the generation of interrupts in either the
general-purpose recognition mode or the specific conditions
mentioned above.
The generality of the above provides a modicum of compatibility to
BOP (Bit Oriented Protocol) where the generation and detection of
‘flags’ is required. Parts of usually synchronous BOP protocols
(HDLC in particular) are beginning to show up in asynchronous
formats.
Character Stripping
The MR0[7:6] register provides for stripping the characters used for
character recognition. Recall that the character recognition may be
conditioned to control several aspects of the communication.
However this system is first a character recognition system. The
status of the various states of this system is reported in the XISR
and ISR registers. The character stripping of this system allows for
the removal of the specified control characters from the data stream:
two for the Xon /Xoff and one for the wake up. Via control in the
MR0[7:6] register these characters may be discarded (stripped) from
the data stream when the recognition system ‘sees’ them or they
may be sent on the RxFIFO. Whether they are stripped or not the
recognition system will process them according to the action
requested; flow control, wake up, interrupt generation, etc. Care
should be exercised in programming the stripping option if noisy
environments are encountered. If a normal character were corrupted
to a Xoff character the transmitter would be stopped. If that
character were now stripped from the FIFO stack, then that stripping
action would make it difficult to determine the cause of transmitter
stopping.
Many users prefer polled to interrupt driven service where there are
not a large number of fast data channels and/or the host CPU’s
other interrupt overhead is low. The Dual UART is functional in this
environment.
The most efficient method of polling is the use of the ‘update CIR’
command (with the interrupt threshold set to zero) followed by a
read of the CIR. This dummy write cycle will perform the same CIR
capture function that an IACKN falling edge would accomplish in an
interrupt driven system. A subsequent read of the CIR, at the same
address, will give information about an interrupt, if any. If the CIR
type field contains 0s, no interrupt is awaiting service. If the value is
non-zero, the fields of the CIR may be decoded for type; channel
and character count information. Optionally, the global interrupt
registers may be read for particular information about the interrupt
status or use of the global RxD and TxD registers for data transfer
as appropriate. The interrupt context will remain in the CIR until
another update CIR command or an IACKN cycle is initiated by the
host CPU occurs. The CIR loads with x’00 if Update CIR is asserted
when the arbitration circuit has NOT detected an arbitration value
that exceeds the threshold value of the ICR. The global registers
and CIR may be used as ‘vectors’ to the service type required.
Traditional methods of polling status registers may also be used.
Their lower efficiency may be greatly offset by use of the UCIR
command and the read of the CIR. They reduce the many reads and
tests of status registers to only one read and one write. This would
normally be accomplished by setting the interrupt threshold to zero.
Then the moment any system within the DUART needs service the
next poll of the CIR would return a non zero value and the type field
will inform the processor which of the possible 18 systems needs
service. In the case of the FIFOs the number of bytes to be written
or read is also available.
Character and Address Recognition
(Also used for Multi-drop, Xon/Xoff systems)
Character recognition is specific to each of the two UARTs. Three
programmable characters are provided for the character recognition
for each channel. The three are general purpose in nature and may
be set to only cause an interrupt or to initiate some rather complex
2005 Nov 01
When character stripping is invoked and a recognition character is
received that has an error bit set that character is sent to the
RxFIFO even though character stripping is active.
Flow Control (Xon/Xoff)
This section describes in-band flow control or Xon/Xoff signaling.
For the RTS/CTS hardware (out-of-band) control see MR1(7) and
MR2(4) descriptions.
The flow control is accomplished via the character recognition
system giving recognition information to the flow control processor.
Xon and Xoff are special characters used by a receiver to start and
stop the remote transmitter that is sending it data. As described
below several modes of manual and automatic flow control are
available by program control.
15
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
NOTE: To be recognized as a Xon or Xoff character, the receiver
must have room in the RxFIFO to accommodate the character. An
Xon/Xoff character that is received resulting in a receiver overrun
does not effect the transmitter nor is it loaded into the RxFIFO,
regardless of the state of the Xon/Xoff transparency bit, MR3[7].
The modes of control are described in MR3[3:2]
00 = Host mode
01 = Auto transmit
10 = Auto Receive
11 = Auto receive and transmit
Mode control
Xon/Xoff mode control is accomplished via the MR3[3:2].
00
Xon/Xoff processing disabled. The host will control Rx, Tx.
01
Auto Tx control. Tx is stopped/started when Xoff/Xon is
received.
10
Auto Rx control. Receiver commands Tx to send Xoff at
trigger level.
11
Auto Rx and Tx control. Receiver commands Tx to send
Xoff as the receiver fills and commands the Tx to send
Xon when Rx FIFO fill level is lowered. This results in total
automatic control. No processor interrupt is required.
Receiver Mode
Since the receiving FIFO resources in the Dual UART are limited,
some means of controlling a remote transmitter is desirable in order
to lessen the probability of receiver overrun. The Dual UART
provides two methods of controlling the data flow. There is a
hardware-assisted means of accomplishing control, the so-called
out-of-band flow control, and an in-band flow control method.
The out-of-band flow control is implemented through the
CTSN–RTSN signaling via the I/O ports. The operation of these
hardware handshake signals is described in the receiver and
transmitter discussions.
In-band flow control is a protocol for controlling a remote transmitter
by embedding special characters within the message stream, itself.
Two characters, Xon and Xoff, which do not represent normal
printable character take on flow control definitions when the
Xon/Xoff capability is enabled. Flow control characters received may
be used to gate the channel transmitter on and off. This activity is
referred to as Auto-transmitter mode. To protect the channel receiver
from overrun, fixed fill levels (hardware set at 240 characters) of the
RxFIFO may be employed to automatically insert Xon/Xoff
characters in the transmitter’s data stream. This mode of operation
is referred to as auto-receiver mode. Commands issued by the host
CPU via the CR can simulate all these conditions.
Note that MR3[7] controls the stripping of Xoff/Xon characters.
0
Xon/Xoff characters are sent to the Rx FIFO
1
Xon/Xoff characters are discarded.
The MR3[7] functions regardless of the setting of MR3[3:2]. This
allows for general purpose character recognition and processing.
(See ‘Character Stripping’.)
Xon Xoff Characters
The programming of these characters is usually done individually.
The standard Xon/Xoff characters are . Xon is 0x11, Xoff 0x13. Any
enabling of the Xon/Xoff functions will use the contents of the Xon
and Xoff character registers as the basis on which recognition is
predicated.
Host mode
When neither the auto-receiver or auto-transmitter modes are set,
the Xon/Xoff logic is operating in the host mode. In host mode, all
activity of the Xon/Xoff logic is initiated by commands to the CRx.
The Xoff command forces the transmitter to disable exactly as
though a Xoff character had been received by the RxFIFO. The
transmitter will remain disabled until the chip is reset or the CR (7:3)
= 10110 (Xoff resume) command is given. In particular, reception of
a Xon or disabling or re-enabling the transmitter will NOT cause
resumption of transmission. Redundant CRTXxx commands, i.e.
CRTXon, CRTXon, are harmless, although they waste time. A
CRTXon may be used to cancel a CRTXoff (and vice versa) but both
may be transmitted depending on the command timing with respect
to that of the transmitter state machine.
Auto-transmitter mode
When a channel receiver loads a Xoff character into the RxFIFO, the
channel transmitter will finish transmission of the current character
and then stop transmitting. A transmitter so idled can be restarted by
the receipt of a Xon character by the receiver or by a hardware or
software reset. The last option results in the loss of the
untransmitted contents of the TxFIFO. When operating in this mode
the Command Register commands for the transmitter are not
effective.
Auto Receive and Transmit
This is a combination of both modes.
NOTE: Xon /Xoff characters
The Xon/Xoff character with errors will be accepted as valid. The
user has the option sending or not sending these characters to the
FIFO. Error bits associated with Xon/Xoff will be stored normally to
the receiver FIFO.
The channel’s transmitter may be programmed to automatically
transmit a Xoff character without host CPU intervention when the
RxFIFO fill level exceeds a fixed limit (240). In this mode it will
transmit a Xon character when the RxFIFO level drops below a
second fixed limit (16). A character from the TxFIFO that has been
loaded into the TxD shift register will continue to transmit.
Character(s) in the TxFIFO that have not been loaded to the
transmitter shift register are unaffected by the Xon or Xoff
transmission. They will be transmitted after the Xon/Xoff activity
concludes.
If the fill level condition that initiates Xon activity negates before the
flow control character can begin transmission, the transmission of
the flow control character will not occur. That is, either of the
following sequences may be transmitted depending on the timing of
the FIFO level changes with respect to the normal character times:
Fix This
While idle data may be written to the TxFIFO and it continue to
present its fill level to the interrupt arbiter and maintains the integrity
of its status registers.
Use of ’00’ as a Xon/Xoff character is complicated by the Receiver
break operation which loads a ’00’ character on the RxFIFO. The
Xon/Xoff character detectors do not discriminate in this case from a
Xon/Xoff character received through the RxD pin.
2005 Nov 01
Character
Xoff
Character
Character
Xon
Character
Hardware keeps track of Xoff characters sent that are not rescinded
by a Xon. This logic is reset by writing MR3[3:2] to ‘00’. If the user
drops out of Auto-receiver mode while the XISR shows Xoff as the
16
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
NOTE: Care should be taken in the programming of the character
recognition registers. Programming x’00, for example, may result in
a break condition being recognized as a control character. This will
be further complicated when binary data is being processed.
last character sent the Xon/Xoff logic would not automatically send
the negating Xon.
The kill CRTX command (of the command register) can be used to
cleanly terminate any pending CRTX commands.
NOTE: In no case will a Xon/Xoff character transmission be aborted.
Once the character is loaded into the TX Shift Register, transmission
continues until completion or a chip reset or transmitter reset is
encountered. The kill CRTX command has no effect in either of the
Auto modes.
PROGRAMMING THE HOST INTERFACE
The SC28L202 is designed for a very close compatibility with legacy
software written for other Philips/Signetics 2 channel UARTs. The
part will initialize to the SC28L92 function. This function is controlled
in the low 16 address positions.
Xon/Xoff Interrupts
The Xon/Xoff logic generates interrupts only in response to
recognizing either of the characters in the XonCR or XoffCR (Xon or
Xoff Character Registers). The transmitter activity initiated by the
Xon/Xoff logic or any CR command does not generate an interrupt.
The character comparators operate regardless of the value in
MR3[3:2]. Hence the comparators may be used as general-purpose
character detectors by setting MR3[3:2]= ‘00’ and enabling the
Xon/Xoff interrupt in the IMR.
A reset (both hardware and software) will return the part to this
mode with the control registers set for 9600 baud, 8 bits, no parity
and one stop bit. Interrupt will be set for Receiver Ready and
transmitter Empty. Transmitters and receivers will not be enabled.
Basic operation should be obtained by a single write of 0xE0 to the
command register. That will enable the receiver and transmitter.
Addressing outside of the lower 16 address spaces will enable all
the advanced features. In general, before calling legacy code,
advanced features should be disabled (character stripping, for
example).
The Dual UART can present the Xon/Xoff recognition event to the
interrupt arbiter for IRQN generation. The IRQN generation may be
masked by setting bit 4 of the Interrupt Mask Register, IMR. The bid
level of a Xon/Xoff recognition event is controlled by the Bidding
Control Register X, BCRx, of the channel. The interrupt status can
be examined in ISR[4]. If cleared, no Xon/Xoff recognition event is
interrupting. If set, a Xon or Xoff recognition event has been
detected. The X Interrupt Status Register, XISR, can be read for
details of the interrupt and to examine other, non-interrupting, status
of the Xon/Xoff logic. Refer to the XISR in the Register Descriptions.
Writing control words into the appropriate registers programs the
operation of the DUART. Operational feedback is provided via status
registers that can be read by the CPU. The addressing of the
registers is described in the Register Map.
The contents of certain control registers are initialized to zero on
RESET. Care should be exercised if the contents of a register are
changed during operation, since certain changes may cause
operational problems.
The character recognition function and the associated interrupt
generation is disabled on hardware or software reset.
For example, changing the number of bits per character while the
transmitter is active may cause the transmission of an incorrect
character. In general, the contents of the MR, the CSR, and the
OPCR should only be changed while the receiver(s) and
transmitter(s) are not enabled, and certain changes to the ACR
should only be made while the C/T is stopped.
Multi-drop or Wake up or 9 bit mode
This mode is used to address a particular UART among a group
connected to the same serial data source. Normally it is
accomplished by redefining the meaning of the parity bit such that it
indicates a character as address or data. While this method is fully
supported in the SC28L202 it also supports recognition of the
character itself. Upon recognition of its address the receiver will be
enabled and data loaded onto the RxFIFO.
Each channel has 3 mode registers (MR0, 1, 2) which control the
basic configuration of the channel. Mode, command, clock select,
and status registers are duplicated for each channel to provide total
independent operation and control. Refer to Table 2 for register bit
descriptions.
Further the Address recognition has the ability, if so programmed, to
disable (not reset) the receiver when an address is seen that is not
recognized as its own. The particular features of ‘Auto Wake and
Auto Doze’ are described in the detail descriptions under ‘Receiver
Operation’ above.
2005 Nov 01
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
To facilitate this feature the complete register function and control of
the SC26C92 is replicated in the SC28L202. That is code written for
the SCN2681, SCN68681, SCC2692, SCC68692 and SC26C92 will
operate with this device.
REGISTER DESCRIPTION AND PROGRAMMING
NOTE
Programmers may use either of two register sets or mix the features
of each. It is suggested that only the extended register set be used
in new designs. However if a system needed to use a block of
communications code written for an older system then that code
could merely be called. This is similar to calling a DOS program in
a WINDOWS environment. Before calling legacy code it is
recommended (but not required) to execute ‘Reset to C92’
command. Also consideration must be given to the I/O pins to avoid
contention of drivers of the pins and an external driver.
With the execution of code written for previous DUARTs and
immediately after a hardware reset or a ‘Reset to C92’ command the
following configuration will exist:
1. The size of all FIFOs is set to 8 bytes (for legacy code).
2. FIFO interrupt levels are controlled by the bits of the MR
registers
Two control register descriptions and maps are implemented in the
SC28L92: one represents the previous 4-bit address and the other
the new 7-bit address space representing the all the new features of
the new design.
3. All I/O ports are set to input.
The Design of the SC28L202 allows for high degree with former
Philips two channel communications controllers—DUARTs.
6. Baud selection follows previous 4 bit programming and baud rate
grouping controlled by the MR and ACR registers.
4. Receiver FIFO set to interrupt on FIFO ready.
5. Transmitter FIFO set to interrupt on FIFO empty.
Table 2. SC28L202 REGISTER BIT DESCRIPTIONS
Registers that control Global Properties of the 28L202
GCCR – Global Configuration Control Register
THIS IS A VERY IMPORTANT REGISTER! IT SHOULD BE THE FIRST REGISTER ADDRESSED DURING INITIALIZATION.
Hex
Bit [7:6]
Bit [5:3]
Bit [2:1]
BIT 0
Addr
DACKN Assertion
Reserved
IVC Interrupt Vector Control
ISR Read Mode
00 = no interrupt vector
01 = IVR[7:0]
10 = IVR[7:1] + channel code
11 = IVR[7:5] + interrupt type + channel code
0 = ISR Unmasked
1 = ISR Read Masked by IMR
00 = 2 – 3 Sclk
01 = 1 – 2 Sclk
10 = 1/2 – 1 Sclk
11 = Reserved
Set to 0
If IVC = 0x10, the channel code will replace the LSB of the IVR; if
IVC = b’11 then a modified interrupt type and channel code replace
the 3 LSBs of the IVR. NOTE: The modified type field IVR[2:1] is:
GCCR(7:6) DACKN Assertion
Motorola bus cycle time can be controlled by selecting a DACKN
assertion time based on X1/Sclk speed. The time programmed
should not be less than the minimum read or write pulse width.
• 10 Receiver w/o error
• 11 Receiver with error
• 01 Transmitter
• 00 All remaining sources
See examples below.
X1/SCLK
#SCLK Cycles
Delay
3.6864 MHz
1/2–1
136–272 ns
7.3728 MHz
1/2–1
68–136 ns
14.7456 MHz
1/2–1
34–68 ns
29.4912 MHz
1–2
34–68 ns
33.1776 MHz
2–3
60–90 ns
44.2368 MHz
2–3
46–68 ns
GCCR(0): Interrupt Status Masking
This bit controls the readout mode of the Interrupt Status Register,
ISR. If set, the ISR reads the current status masked by the IMR, i.e.
only interrupt sources enabled in the IMR can ever show a ‘1’ in the
ISR. If cleared, the ISR shows the current status of the interrupt
source without regard to the Interrupt Mask setting.
GCCR(5:3): Reserved
GCCR(2:1): Interrupt vector configuration
The IVC field controls if and how the assertion of IACKN (the
interrupt acknowledge pin) will form the interrupt vector for the
DUART. If b’00, no vector will be presented during an IACKN cycle.
The bus will be driven high (0xFF). If the field contains a b’01, the
contents of the IVR, Interrupt Vector Register, will be presented as
the interrupt vector without modification.
2005 Nov 01
18
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
SFSR A and B Special Feature & Status Register
Bit 7
Bit 6
Bit 5
BIT 4
BIT 3
BIT 2:1
BIT 0
Reserved
Reserved
Reserved
Reserved
Loop Back Error
Remote Loop Error Check
Reserved
0 = No
1 = Yes
(read Only)
00 = Disabled
01 = Enabled, RxC ← TxC
10 = Enabled, RxC ← TxCN
to two characters in time . This mode will totally relieve the
processor of this task where certainty of transmission and reception
is required. The transmitted data is looped back by the remote
station with a half-bit time delay. The local transmitted data is
internally sent to the local receiver for comparison. An interrupt is
generated in the case of an error (data mismatch, parity or framing).
SFSR(7:4) Reserved
SFSR(3) Status of loop back error check.
A ‘1’ indicates a loop back error occurred, which will be entered for
interrupt arbitration.
It can be cleared by the processor by a write to this register with
D(3) equal to ‘1’.
00 = The checking is disabled
SFSR(2:1) Certification of returned data as Valid (This feature
implies the transmitted data is being returned by the remote
receiver. )
01 = Return data is clocked in on rise of TxC
Sets automatic checking of returned data. This mode stores
transmitted data and compares it to data returned from the remote
receiver. It is used where relative short delay times are available, up
00 = Reserved
10 = Return data is clocked on of rise of TxCN
SFSR(0) Reserved
TRR Test and Revision Register.
TRR
Bit 7
Bit 6:0
Test 2
Revision Code
TRR[7] Test 2 Enable
Bypass divide by 16 counter in all TxC and RxC.
TRR[6:0] – Chip Revision Code
Indicates the revision of the chip. Initial code will be 0000000. The
revision code bits [6:0] are hard wired. The default setting of the test
bits is all zero.
STCR – Scan Test Control Register.
Addr
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
77
BIT 2
BIT 1
BIT 0
Memory Test
Scan Test
Iddq Test
STCR(0) Iddq Test – Turns off all pull-up devices on the I/O pins.
SES – System Enable Status Register, A and B
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reserved
Reserved
Transmitter
Enabled
Receiver
Enabled
Watch Dog
Timer
Address
Recognition
Xon
Xoff
Set to 0
Set to 0
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
This register reports the enabled status of the several sub systems in the DUART. These systems are sometimes controlled by the state
machines of the receiver FIFOs.
EOS – Enhanced Operation Status Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reserved
I/O Port
Operation
Reserved
Counter/Timer
0 Clock Select
Channel B
Rx/Tx
Clock
Selection
Channel A
Rx/Tx
Clock
Selection
Channel B
FIFO
Interrupt Level
Control
Channel A FIFO
Interrupt Level
Control
0 = Default
1 = Enhanced
0 = Default
1 = Enhanced
0 = Default
1 = Enhanced
0 = Default
1 = Enhanced
0 = Default
1 = Enhanced
0 = Default
1 = Enhanced
This register reports the status of the Enhanced operation in several sub systems in the DUART.
2005 Nov 01
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Philips Semiconductors
Product data sheet
Dual UART
SC28L202
times, thus rendering later transmission or reception faulty or
impossible.
UART Registers
These registers are generally concerned with formatting,
transmitting and receiving data.
The user must exercise caution when changing the mode of running
receivers, transmitters, PBRG or counter/timers. The selected mode
will be activated immediately upon selection, even if this occurs
during the reception or transmission of a character. It is also
possible to disrupt internal controllers by changing modes at critical
An exception to this policy is switching from auto-echo or remote
loop back modes to normal mode. If the deselecting occurs just after
the receiver has sampled the stop bit (in most cases indicated by
the assertion of the channel’s RxRDY bit) and the transmitter is
enabled, the transmitter will remain in auto-echo mode until the end
of the transmission of the stop bit.
MR0 – Mode Register 0, A and B
MR0 can be accessed directly at H’20’ and H’28’ in the Extended section of the address map, or by means of the ‘MR Pointers’ at the 0x00 and
0x08 address pointers used by legacy code.
MR0 A, MR0
B, and
MR0 B[3:0]
are reserved
Bit 7
BIT 6
BIT (5:4)
BIT 3
BIT 2
BIT 1
BIT 0
Rx Watchdog
*
0 = Disable
1 = Enable
RxINT BIT 2
See Tables in
MR0
description
TxINT (1:0)
See Table 13
FIFO Size
0 = 8 bytes
1 = 256
bytes
BAUD RATE
EXTENDED II
0 = NormaL
1 = Extend II
Reserved
Set to 0
BAUD RATE
EXTENDED 1
0 = Normal
1 = Extend
*This bit control is duplicated at WCXER[7:6], the Watch Dog, Character, Address and X Enable Register.
MR0[5:4] – Tx interrupt fill level.
MR0[7] Fixed length Watchdog Timer
This bit controls the receiver watchdog timer. 0 = disable, 1 =
enable. When enabled, the watch dog timer will generate a receiver
interrupt if the receiver FIFO has not been accessed within 64 bit
times of the receiver 1X clock. This is used to alert the control
processor that data is in the RxFIFO that has not been read. This
situation may occur when the byte count of the last part of a
message is not large enough to generate an interrupt.
Table 5. Transmitter FIFO Interrupt Fill Level
MR0(3)=0
MR0[5:4]
00
01
10
11
MR0[6] – Bit 2 of receiver FIFO interrupt level. This bit along with Bit
6 of MR1 sets the fill level of the 8 byte FIFO that generates the
receiver interrupt.
Table 6. Transmitter FIFO Interrupt Fill Level
MR0(3)=0
MR0[6] and MR1[6] Note that this control is split between MR0 and
MR1. This is for backward compatibility to the SC2692 and
SCN2681.
MR0[5:4]
00
01
10
11
Table 3. Receiver FIFO Interrupt Fill Level
MR0(3)=0
MR0[6] MR1[6]
00
01
10
11
Interrupt Condition
1 or more bytes in FIFO (RxRDY)
3 or more bytes in FIFO
6 or more bytes in FIFO
8 bytes in FIFO (Rx FULL)
Interrupt Condition
256 bytes empty (Tx EMPTY)
128 or more bytes empty
192 or more bytes empty
1 or more bytes empty (TxRDY)
For the transmitter these bits control the number of FIFO positions
empty when the receiver will attempt to interrupt. After the reset the
transmit FIFO has 8 bytes empty. It will then attempt to interrupt as
soon as the transmitter is enabled. The default setting of the MR0
bits (00) condition the transmitter to attempt to interrupt only when it
is completely empty. As soon as one byte is loaded, it is no longer
empty and hence will withdraw its interrupt request.
Table 4. Receiver FIFO Interrupt Fill Level
MR0(3)=1
MR0[6] MR1[6]
00
01
10
11
Interrupt Condition
8 bytes empty (Tx EMPTY)
4 or more bytes empty
6 or more bytes empty
1 or more bytes empty (TxRDY)
MR0[3] – FIFO Size
Selects between 8 or 256 byte FIFO structure
Interrupt Condition
1 or more bytes in FIFO (RxRDY)
128 or more bytes in FIFO
192 or more bytes in FIFO
256 bytes in FIFO (Rx FULL)
MR0[2:0] – Legacy Baud Rate Group Selection
These bits are used to select one of the six-baud rate groups.
See Table 13 for the group organization.
• 000 Normal mode
• 001 Extended mode I
• 100 Extended mode II
For the receiver these bits control the number of FIFO positions
filled when the receiver will attempt to interrupt. After the reset the
receiver FIFO is empty. The default setting of these bits cause the
receiver to attempt to interrupt when it has one or more bytes in it.
Other combinations of MR2[2:0] should not be used
NOTE: MR0[3:0] are not used in channel B and should be set to 0.
2005 Nov 01
20
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
MR1 – Mode Register 1, A and B
MR1 can be accessed directly at H’21’ and H’29’ in the Extended section of the address map, or by means of the ‘MR Pointers’ at the 0x00 and
0x08 address pointers used by legacy code.
Bit 7
RxRTS Control
Bit 6
See Tables in MR0
description
0 = off
1 = on
Bit 5
Error Mode
Bit 4:3
Parity Mode
Bit 2
Parity Type
Bit 1:0
Bits per
Character
0 = Character
1 = Block
(entry or exit)
00 = With Parity
01 = Force parity
10 = No parity
11 = Multi drop Special Mode
0 = Even
1 = Odd
00 = 5
01 = 6
10 = 7
11 = 8
MR1 [5] – Error Mode Select and sub modes
This bit selects the operating mode of the three FIFOed status bits
(FE, PE, and received break). In the character mode, status is
provided on a character by character basis; the status applies only
to the character at the output of the FIFO.
MR1[7] – Receiver Request to Send (hardware flow control)
This bit controls the deactivation of the RTSN output (I/O2) by the
receiver. The I/O2 output is asserted and negated by commands
applied via the command register or through the setting of the OPR
register bits. MR1[7] = 1 enables the receiver state machine to
controls the sate of the I/O2 (where the RTSN function is assigned)
to be automatically negated (driven high) upon receipt of a valid start
bit if the receiver FIFO is 240 full or greater. (for 8-byte mode the
FIFO full signal is used) RTSN is reasserted when the FIFO fill level
falls below 240 filled FIFO positions. This constitutes a change from
previous members of Philips (Signets)’ UART families where the
RTSN function triggered on FIFO full. This behavior caused
problems with PC UARTs that could not stop transmission at the
proper time.
In the block mode, the status provided in the SR for these bits is the
accumulation (logical OR) of the status for all characters coming to
the output of the FIFO, since the last reset error command was
issued.
The Block Error mode has two-sub mode. These modes are
controlled by the command register. The error is ‘accumulated’ (as
described above) at either the entry of the data in to the FIFO or on
the exit (read of the FIFO). Of the two the setting of the error on the
entry of the data into the FIFO gives the earliest warning of error
data.
NOTE: When the FIFO is set to an 8-byte depth the RTSN signaling
is triggered on position 8 of the FIFO
The RTSN feature can be used to prevent overrun in the receiver, by
using the RTSN output signal, to control the CTSN (see MR2(4)
description) input of the transmitting device. It is not recommend to
use the hardware flow control and the ‘in-band’ (Xon/Xoff) flow
control at the same time although the DUART hardware will allow it.
MR1[4:3] – Parity Mode Select
If ’with parity’ or ’force parity’ is selected, a parity bit is added to the
transmitted character and the receiver performs a parity check on
incoming data. MR1[4:3] = 11 selects the channel to operate in the
special wake up mode.
To use the RTSN function:
1. Set MR1(7) to 1
MR1[2] – Parity Type Select
This bit sets the parity type (odd or even) if the ’with parity’ mode is
programmed by MR1[4:3], and the polarity of the forced parity bit if
the ’force parity’ mode is programmed it has no effect if the ’no
parity’ mode is programmed. In the special ’wake up’ mode, it
selects the polarity of the A/D bit. The parity bit is used to an
address or data byte in the ’wake up’ mode.
2. Set I/O0 B or I/O1 B as appropriate to logical 0
3. Enable receiver
MR1[6] – Receiver interrupt control bit 1.
See description under MR0 [6]. (Writing to this register will reset the
RxFIFO interrupt to the bit configuration of MR0 and MR1. Reading
has no effect.)
MR1[1:0] – Bits per Character Select
This field selects the number of data bits per character to be
transmitted and received. This number does not include the start,
parity, or stop bits.
*** change in MR in legacy section – at MR0 also***
2005 Nov 01
21
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
MR2 – Mode Register 2, A and B
MR2 can be accessed directly at 0x22 and 0x2A in the Extended section of the address map, or by means of the ‘MR Pointers’ at the 0x00 and
0x08 address pointers used by legacy code.
The MR2 register provides basic channel set-up control that may need more frequent updating.
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
MR2 A
CHANNEL MODE
Tx CONTROLS
CTS
STOP BIT LENGTH
MR2 B
RTS
ENABLE Tx
NOTE: Add 0.5 to binary codes 0 – 7 for 5 bit character lengths.
00 = Normal
01 = Auto-Echo
10 = Local loop
11 = Remote loop
0 = No
1 = Yes
0 = No
1 = Yes
0 = 0.563 4 = 0.813 8 = 1.563 C = 1.813
1 = 0.625 5 = 0.875 9 = 1.625 D = 1.875
2 = 0.688 6 = 0.938 A = 1.688 E = 1.938
3 = 0.750 7 = 1.000 B = 1.750 F = 2.000
NOTE:
1. Add 0.5 to values shown for 0 – 7 if channel is programmed for 5 bits/char.
• A received break is echoed as received until the next valid start bit
MR2[7:6] – Mode Select
The DUART can operate in one of four modes: Normal, Automatic
Echo, Local Loop Back and Remote Loop Back
is detected.
MR2[5] Transmitter Request to Send Control
This bit controls the deactivation of the RTSN output (I/O2) by the
transmitter. This output is manually asserted and negated by
appropriate commands issued via the command register. MR2 [5] = 1
negates (drives to logical 1) RTSN automatically one bit time after
the characters in the transmit shift register and in the TxFIFO (if any)
are completely transmitted (includes the programmed number of
stop bits if the transmitter is not enabled). This feature can be used
to automatically terminate the transmission of a message as follows:
• Program auto reset mode: MR2[5]= 1.
MR2[7:6] = b’00 Normal Mode
Normal and default mode The transmitter and receiver operating
independently.
MR2[7:6] = b’01 Automatic Echo
Places the channel in the automatic echo mode, which automatically
retransmits the received data. The following conditions are true
while in automatic echo mode:
• Received data is re-clocked and re-transmitted on the TxD output.
• The receiver clock is used for the transmitted data.
• The receiver must be enabled, but the transmitter need not be
• Enable transmitter.
• Assert RTSN via command.
• Send message.
• Verify the next to last character of the message is being sent by
enabled.
• The TxRDY and Tx Idle status bits are inactive.
• The received parity is checked, but is not regenerated for
transmission, i.e., transmitted parity bit is as received.
• Character framing is checked, but the stop bits are retransmitted
•
•
•
as received. Rx data is sent to RxFIFO
A received break is echoed as received until the next valid start bit
is detected.
CPU to receiver communication continues normally, but the CPU
to transmitter link is disabled.
NOTE: when the transmitter controls the RTSN pin the meaning of
the pin is COMPLETELY changed. It has nothing to do with the
normal RTSN/CTSN ‘handshaking’. It is usually used to mean, ‘end
of message’ and to ‘turn the line around’ in simplex communications.
From a practical point of view the simultaneous use of Tx control of
RTSN and Rx control is mutually exclusive. However if this is
programmed the DUART performs as required.
MR2[7:6] = b’10 selects local loop back diagnostic mode. In this mode:
• The transmitter output is internally connected to the receiver input.
• The transmitter’s 1X clock is used for the receiver.
• The TxD output is held high.
• The RxD input is ignored.
• The transmitter must be enabled, but the receiver need not be
MR2[4] – Clear to Send Control
The state of this bit determines if the CTSN input (I/O0) controls the
operation of the transmitter. If this bit is 0, CTSN has no effect on the
transmitter. If this bit is a 1, the transmitter checks the state of CTSN
each time it is ready to begin sending a character. If it is asserted
(low), the character is transmitted. If it is negated (high), the TxD
output remains in the marking state and the transmission is delayed
until CTSN goes low. Changes in CTSN, while a character is being
transmitted, do not affect the transmission of that character. This
feature can be used to prevent overrun of a remote receiver.
enabled.
• CPU to transmitter and receiver communications continue
normally.
MR2 [7:6] = b’11 Selects the Remote Loop back diagnostic mode.
In this mode:
• Received data is re-clocked and re-transmitted on the TxD output.
• The receiver 1X clock is used for the transmitted data.
• Received data is not sent to the local CPU, and the error status
MR2[3:0] – Stop Bit Length Select
This field programs the length of the stop bit appended to the
transmitted character. Stop bit lengths of 9/16 through 2 bits can be
programmed. In all cases, the receiver only checks for a mark
condition at the center of the first stop bit position (one bit time after
the last data bit, or after the parity bit if parity is enabled). If an
external 1X clock is used for the transmitter, MR2[1] = 0 selects one
stop bit and MR2[1] = 1 selects two stop bits to be transmitted.
conditions are inactive.
• The received parity is not checked and is not regenerated for
transmission, i.e., the transmitted parity bit is as received.
• The receiver must be enabled, but the transmitter need not be
enabled.
• Character framing is not checked, and the stop bits are
retransmitted as received.
2005 Nov 01
waiting until transmitter ready is asserted. Disable transmitter after
the last character is loaded into the TxFIFO.
The last character will be transmitted and RTSN will be reset one
bit time after the last stop bit.
22
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
MR3 – Mode Register 3, A and B
Bit 7
Bit 6
Bit 5:4
Bit 3:2
Bit 1:0
Xon/Xoff 1
transparency
Address Recognition 1
transparency
Reserved
In-band flow control
mode
Address
Recognition
control
0 = flow control characters
received are loaded onto
the RxFIFO
0 = Address characters
received are loaded to
RxFIFO
1 = flow control characters
received are not loaded
onto the RxFIFO
1 = Address characters
received are not loaded onto
the RxFIFO
00 = host mode, only the host
CPU may initiate flow control
actions through the CR
01 = Auto Transmitter flow
control
10 = Auto Receiver flow control
11 = Auto Rx and Tx flow control
00 = Default
01 = Auto wake
10 = Auto doze
11 = Auto wake
and auto doze
NOTE:
1. If these bits are not 0 the characters will be stripped regardless of bits (3:2) or (1:0)
b’00 in this field precludes the use of the command register to
transmit Xon/Xoff characters.
MR3[7 & 6] Xon/Xoff Character Stripping
Control the handling of recognized Xon/Xoff or Address characters.
If set, the character codes are placed on the RxFIFO along with their
status bits just as ordinary characters are. If the character is not
loaded onto the RxFIFO, its received status will be lost unless the
receiver is operating in the block error mode, see MR1[5] and the
general discussion on receiver error handling. Interrupt processing
is not effected by the setting of these bits. See Character recognition
section.
NOTE: Interrupt generation in Xon/Xoff processing is controlled by
the IMR (Interrupt Mask Register) of the individual channels. The
interrupt may be cleared by a read of the XISR, the Xon/Xoff
Interrupt Status Register. Receipt of a flow control character will
always generate an interrupt if the IMR is so programmed. The
MR0[3:2] bits have effect on the automatic aspects of flow control
only, not the interrupt generation.
MR3[5:4] Reserved
MR3[1:0] Address Recognition
This field controls the operation of the Address recognition logic. If
the device is not operating in the special or ‘wake-up’ mode, this
hardware may be used as a general-purpose character detector by
choosing any combination except b’00. Interrupt generation is
controlled by the channel IMR. The interrupt may be cleared by a
read of the XISR, the Xon/Xoff Interrupt Status Register. See further
description in the section on the Wake Up mode.
MR3[3:2] Xon/Xoff Processing
Control the Xon/Xoff processing logic. Auto Transmitter flow control
allows the gating of Transmitter activity by Xon/Xoff characters
received by the Channel’s receiver. Auto Receiver flow control
causes the Transmitter to emit an Xoff character when the RxFIFO
has loaded to a depth of 240 characters. Draining the RxFIFO to a
level of 128 or less causes the Transmitter to emit a Xon character.
All transmissions require no host involvement. A setting other than
2005 Nov 01
23
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
RxCSR – Receiver Clock Select Register A and B
TxCSR Transmitter Clock Select Register A and B
Both registers consist of single 6-bit field that selects the clock source for the receiver and transmitter respectively. During a read the unused
bits in this register read b’000. The ‘BRG’ baud rates (fixed BRG rates) shown in the table below are based on the Sclk crystal frequency of
14.7456 MHz. The baud rates shown below will vary as the Sclk crystal clock varies. For example, if the Sclk rate is changed to 7.3728 MHz all
the rates below will reduce by 1/2.
Bit 7
Bit 6
Bits 5:0
Reserved
Reserved
Transmitter/Receiver Clock select code,
See Clock Multiplex Table below
Rx and Tx Clock Select Table
NOTE: Sclk maximum rate is 50 MHz. Data clock rates will follow exactly the ratio of the X1/Sclk to 14.7654 MHz
Tx A Clock Select Code
Clock selection, Sclk = 14.7456 MHz
Tx A Clock Select Code
Clock selection, Sclk = 14.7456 MHz
00 0000
BRG – 50
01 0000
BRG – 75
00 0001
BRG – 110
01 0001
BRG – 150
00 0010
BRG – 134.5
01 0010
BRG – 450
00 0011
BRG – 200
01 0011
BRG – 1800
00 0100
BRG – 300
01 0100
BRG – 2000
00 0101
BRG – 600
01 0101
BRG – 14.4K
00 0110
BRG – 1200
01 0110
BRG – 19.2K
00 0111
BRG – 1050
01 0111
BRG – 28.8K
00 1000
BRG – 2400
01 1000
BRG – 57.6K
00 1001
BRG – 4800
01 1001
BRG – 115.2K
00 1010
BRG – 7200
01 1010
BRG – 230.4K
00 1011
BRG – 9600
01 1011
BRG – 460.8K
00 1100
BRG – 38.4K
01 1100
BRG – 921.6K
00 1101
Timer 0
01 1101
Timer 1
00 1110
I/O3 A transmitter – 16x External *
01 1110
PBRG 0
00 1111
I/O3 A transmitter – 1x External *
01 1111
Midi rate 31.25 KHz 1.66% error
Tx A Clock Select Code
Clock selection, Sclk = 14.7456 MHz
Tx A Clock Select Code
Clock selection, Sclk = 14.7456 MHz
11 0000 to 11 1101
Reserved
11 1110
PBRG 1
11 1111
Reserved
This field selects the baud rate clock for the Channel A transmitter.
* External clock Pin and external clock mode assignment.
Tx/Rx CSR x [5:0]
RxC Channel A
TxC Channel B
RxC channel B
001110
I/O4 A 16x
I/O5 A 16x
I/O6 A 16x
001111
I/O4 A 1X
I/O5 A 1X
I/O6 A 1X
2005 Nov 01
24
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
CRx – Command Register Extension, A and B
CR is used to write commands to the DUART.
Bit 7
Bit 6
Bit 5
Bit 4:0
Lock Tx and Rx Enables
Enable Tx
Enable Rx
Command Register codes.
0 = lock Rx & Tx state
1 = Change Rx & Tx state
0 = disable
1 = enable
0 = disable
1 = enable
(See Command Register Table)
• 00101 Reset break change interrupt. Causes the break detect
CR[7] – Lock Tx and Rx enables.
‘0’ prevents changing transmitter and receiver enable bits while
writing to the lower 5 bits of the command register. Bits CR[6:5] are
not changed.
change bit in the interrupt status register (ISR[2]) to be cleared to
zero.
• 00110 Start break. Forces the TxD output low (spacing). If the
‘1’ allows the receiver and transmitter enable bits to be changed
while issuing a command to the command register.
transmitter is empty, the start of the break condition will be
delayed up to two bit times. If the transmitter is active and the
TxFIFO is empty then the break begins when transmission of the
current character is completed. If there are characters in the
TxFIFO, the start of break is delayed until all characters presently
in the TxFIFO and any subsequent characters loaded have been
transmitted. (Tx Idle must be true before break begins).
NOTE: Receiver or transmitter disable is not the same as receiver
or transmitter reset.
WRITES TO THE LOWER 5 BITS OF THE CR WOULD USUALLY
HAVE CR[7] AT ‘0’ in order to maintain the enable/disable condition
of the receiver and transmitter. The bit provides a mechanism for
writing commands to a channel, via CR[4:0], without the necessity of
keeping track of or reading the current enable status of the receiver
and transmitter.
The transmitter must be enabled to start a break.
• 00111 Stop break. The TxD line will go high (marking) within two
bit times. TxD will remain high for one bit time before the next
character is transmitted.
CR[6] – Enable Transmitter
A one written to this bit enables operation of the transmitter. The
TxRDY status bit will be asserted. When disabled by writing a zero
to this bit, the command terminates transmitter operation and resets
the TxRDY and Tx Idle status bits returning the transmitter to its idle
state . However, if a character is being transmitted or if characters
are loaded in the TxFIFO when the transmitter is disabled, the
transmission of the all character(s) is completed before assuming
the inactive state.
• 01000 Assert RTSN. Causes the RTSN output to be asserted
(low).
• 01001 Negate RTSN. Causes the RTSN output to be negated
(high).
NOTE: The two commands above actually reset and set,
respectively, the I/O0 B (Channel A) or I/O1 B (Channel B)
pin associated with the OPR register. (See SOPR and
ROPR registers I/O pin control.
CR[5] – Enable Receiver
A one written to this bit enables operation of the receiver. The
receiver immediately begins the search for and the verification the
start bit. If a zero is written, this command terminates operation of
the receiver immediately—a character being received will be lost.
The command has no effect on the receiver status bits or any other
control registers. The data in the RxFIFO will be retained and may
be read. If the receiver is re-enabled subsequent data will be
appended to that already in the RxFIFO. If the special wake-up
mode is programmed, the receiver operates even if it is disabled
(see Wake-up Mode).
• 01010 Set C/T Receiver time out mode on
• 01011 Set MR Pointer to 0
• 01100 Set C/T Receiver time out mode off
• 01101 Block error status accumulation on FIFO entry. Allows the
CR[4:0] – Miscellaneous Commands (See Table below)
The encoded value of this field can be used to specify a single
command as follows:
• 01110 Power Down Mode On
• 01111 Disable Power Down Mode
• 10000 Transmit an Xon Character
• 10001 Transmit an Xoff Character
• 10010 C/T start sets the counter timer to the value of the
‘received break’, ‘framing error’ and ‘parity error’ bits to be set as
the received character is loaded to the RxFIFO. (normally these
bits are set on reading of the data from the RxFIFO) Setting this
mode can give information about error data up to 256 bytes earlier
than the normal mode. However it clouds the ability to know
precisely which byte(s) are in error.
• 00000 No command.
• 00001 Reserved
• 00010 Reset receiver. Immediately resets the receiver as if
hardware reset had been applied. The receiver is reset and the
FIFO pointer is reset to the first location effectively discarding all
unread characters in the FIFO.
counter/timer preset register and starts the counter.
• 10011 C/T stop Effectively stops the counter/timer, captures the
last count value and resets the counter ready status bit in the ISR
• 00011 Reset transmitter. Immediately resets the transmitter as if a
• 10100 Reserved
• 10101 Reserved.
• 10110 Transmitter resume command (This command is not active
hardware reset had been applied. The transmitter is reset and the
FIFO pointer is reset to the first location effectively discarding all
untransmitted characters in the FIFO.
• 00100 Reset error status. Clears the received break, parity error,
in ‘Auto-Transmit mode’). A command to cancel a previous Host
Xoff command. Upon receipt, the channel’s transmitter will
transfer a character, if any, from the TxFIFO and begin
transmission.
framing error, and overrun error bits in the status register
(SR[7:4]). It is used in either character or block mode. In block
mode it would normally be used after the block is read.
2005 Nov 01
25
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
• 10111 Host Xoff (or transmitter pause) command (CRTXoff). This
• 11001 Reserved
• 11010 Reserved
• 11011 Reset Address Recognition Status. This command clears
command allows tight host CPU control of the flow control of the
channel transmitter. When interrupted for receipt of a Xoff
character by the receiver, the host may stop transmission of
further characters by the channel transmitter by issuing the Host
Xoff command. Any character that has been transferred to the
TxD shift register will complete its transmission, including the stop
bit before the transmitter pauses. Even though the transmitter is
paused it is still able to send Xon/Xoff by the request of its
associated receiver.
the interrupt status that was set when an address character was
recognized by a disabled receiver operating in the special mode.
• 11100 Reserved
• 11101 Block error status accumulates on FIFO read (Default
State)
• 11000 Cancel Host transmit flow control command. Issuing this
• 11110 Reset to ‘C92’ Register Set
• 11111 Reserved for channel B, for channel A: executes a chip
command will cancel a previous command to transmit a flow
control character if the flow control character is not yet loaded into
the TxD Shift Register. If there is no character waiting for
transmission or if its transmission has already begun, then this
command has no effect and the character will be sent.
wide reset. Executing this command in channel a is equivalent to
a hardware reset with the RESET(N) pin. Executing in channel B
has no effect.
COMMAND REGISTER EXTENSION TABLE A and B
Commands 0x0E, 0x0F, 0x1F (marked with • ) are global and exist only in channel A’s register space.
Channel
Command
Code
Channel
Command
Channel
Command Code
Channel
Command
CR[4:0]
Description
CR[4:0]
Description
0 0000
NOP
1 0000
Transmit Xon
0 0001
Set MR pointer to 1
1 0001
Transmit Xoff
0 0010
Reset Receiver
1 0010
Start C/T
0 0011
Reset Transmitter
1 0011
Stop C/T
0 0100
Reset Error Status
1 0100
Reserved
0 0101
Reset Break Change Interrupt
1 0101
Reserved
0 0110
Begin Transmit Break
1 0110
Transmitter Resume Command (CRXoffRe)
0 0111
End Transmit Break
1 0111
Host Xoff Command (CRTXoff)
0 1000
Assert RTSN (I/O0 B or I/O1 B)
1 1000
Cancel Transmit X Char Command (CRTX)
0 1001
Negate RTSN (I/O0 B or I/O1 B)
1 1001
Reserved
0 1010
Set C/T Receiver time-out mode on
1 1010
Reserved
0 1011
Set MR pointer to 0
1 1011
Reset Address Recognition Status
0 1100
Set C/T Receiver time-out mode off
1 1100
Reserved
0 1101
Block Error Status on RxFIFO load
1 1101
Block Error Status on RxFIFO Read
0 1110
• Power Down Mode On
1 1110
Reserved
0 1111
• Disable Power Down Mode
1 1111
• Reset Device as a Hardware reset. Reserved in channel B*
2005 Nov 01
26
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
SR – Channel Status Register A and B
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Received Break
Framing Error
Parity Error
Overrun Error
Tx Idle
TxRDY
RxFULL
RxRDY
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
of the last stop bit of a character, if no character is in the TxFIFO
awaiting transmission. It is negated when the TxFIFO is loaded by
the CPU, or when the transmitter is disabled or reset. This bit is
concerned with the transmitter transmitting data and it essentially
shows ‘ transmitter underrun’. If, while it is underrun it is
commanded to send an X on/Xoff character it will remain at the zero
state. If it is underrun and while sending an Xon/Xoff character the
TxFIFO is loaded then the bit will go low.
SR[7] – Received Break
This bit indicates that an all zero character (including parity, if used)
of the programmed length has been received with a stop bit at a
logical zero. A single FIFO position is loaded with 0x00 when a
break is received; further entries to the FIFO are inhibited until the
RxD line returns to the marking state for at least one half bit time
(two successive edges of the internal or external 1x clock). When
this bit is set, the change in break bit in the ISR (ISR [2]) is set.
ISR[2] is also set when the end of the break condition, as defined
above, is detected. The break detect circuitry is capable of detecting
breaks that originate in the middle of a received character. However,
if a break begins in the middle of a character, it must last until the
end of the next character in order for it to be detected.
SR[2] – Transmitter Ready (TxRDY)
This bit, when set, indicates that the TxFIFO is ready to be loaded
with at least one more character. This bit is cleared when the
TxFIFO is full or is above its interrupt threshold level set in the MR
registers or TxFIFO interrupt Fill Level register (TxFIL). Characters
loaded in the TxFIFO while the transmitter is disabled will not be
transmitted.
SR[6] – Framing Error (FE)
This bit indicates that a stop bit was not detected when an otherwise
non-zeros data character (including parity, if enabled) was received.
The stop bit check is made in the middle of the first stop bit position.
SR[1] – RxFIFO Full (RxFULL)
This bit is set when a character is transferred from the receive shift
register to the receive FIFO and the transfer causes the FIFO to
become full, i.e., all 256 RxFIFO positions are occupied. It is reset
when the CPU reads the RxFIFO and that read leaves one or more
empty byte position(s). If a character is waiting in the receive shift
register because the RxFIFO is full, RxFULL is not reset until the
second read of the RxFIFO since the waiting character is
immediately loaded to the RxFIFO.
SR[5] – Parity Error (PE)
This bit is set when the ’with parity’ or ’force parity’ mode is
programmed and the corresponding character in the FIFO was
received with incorrect parity. In the special ’wake up mode’, the
parity error bit stores the received A/D bit.
SR[4] – Overrun Error (OE)
This bit, when set, indicates that one or more characters in the
received data stream have been lost. It is set upon receipt of the
start bit of a new character when the RxFIFO is full and a character
is already in the receive shift register (257 valid characters in the
receiver) waiting for an empty FIFO position. When this occurs, the
character in the receive shift register (and its break detect, parity
error and framing error status, if any) is lost. This bit is cleared by a
reset error status command.
SR[0] – Receiver Ready (RxRDY)
This bit indicates that a character has been received and is waiting
in the RxFIFO to be read by the CPU. It is set when the character is
transferred from the receive shift register to the RxFIFO and reset
when the CPU reads the RxFIFO, and no more characters are in the
RxFIFO.
SR [3] – Transmitter Idle (Tx Idle)
This bit is set when the transmitter underruns, i.e., both the TxFIFO
and the transmit shift register are empty. It is set after transmission
2005 Nov 01
27
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
ISR – Interrupt Status Register A and B
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
I/O Port
Change
of
state
Receiver
Watch-dog
Time-out
Address
recognition event
Xon/off
event
C/T
Ready
Break
Change
Of
state
RxINT
Receiver entered the
arbitration process.
TxINT
Transmitter entered
the arbitration process.
ISR[1] – RxINT. (Also Rx DMA hand shake at I/O pins)
The general function of this bit is to indicate that the RxFIFO has
data available and that it has entered the arbitration process. The
particular meaning of this bit is programmed by RxFIL register. If
programmed as receiver ready (MR2[3:2] = 00), it indicates that at
least one character has been received and is waiting in the RxFIFO
to be read by the host CPU. It is set when the character is
transferred from the receive shift register to the RxFIFO and reset
when the CPU reads the last character from the RxFIFO.
This register provides the status of all potential interrupt sources for
a UART channel. When generating an interrupt arbitration value, the
contents of this register are masked by the interrupt mask register
(IMR). If a bit in the ISR is a ’1’ and the corresponding bit in the IMR
is also a ‘1’; interrupt arbitration for this source will begin. If the
corresponding bit in the IMR is a zero, the state of the bit in the ISR
can have no affect on the IRQN output. Note that the IMR may or
may not mask the reading of the ISR as determined by GCCR[06].
If GCCR[0] is cleared, the reset and power on default, the ISR is
read without modification. If GCCR[0] is set, the read of the ISR
gives a value of the ISR ANDed with the IMR.
If RxFIL is programmed as FIFO full, ISR[1] is set when a character
is transferred from the receive holding register to the RxFIFO and
the transfer causes the RxFIFO to become full, i.e. all 256 FIFO
positions are occupied. It is reset whenever RxFIFO is not full. If
there is a character waiting in the receive shift register because the
FIFO is full, the bit is set again when the waiting character is
transferred into the FIFO.
ISR[7] – Input Change of State.
This bit is set when a change of state occurs at the I/O1 or I/O0
input pins. It is reset when the CPU reads the Input Port Register,
IPR.
ISR[6] Fixed Watchdog Time-out.
This bit is set when the receiver’s watchdog timer has counted more
than 64 bit times since the last RxFIFO event. RxFIFO events are a
read of the RxFIFO or GRxFIFO, or the load of a received character
into the FIFO. The interrupt will be cleared automatically when the
RxFIFO or GRxFIFO is read. The receiver watch-dog timer is
included to allow detection of the very last characters of a received
message that may be waiting in the RxFIFO, but are too few in
number to successfully initiate an interrupt. Refer to the watchdog
timer description for details of how the interrupt system works after a
watchdog time-out.
The other two conditions of these bits, 3/4 and half full operate in a
similar manner. The ISR[1] bit is set when the RxFIFO fill level
meets or exceeds the value; it is reset when the fill level is less. See
the description of the MR2 register.
NOTE: This bit must be at a one (1) for the receiver to enter the
arbitration process. It is the fact that this bit is zero (0) when the
RxFIFO is empty that stops an empty FIFO from entering the
interrupt arbitration. Also note that the meaning if this bit is not quite
the same as the similar bit in the status register (SR).
ISR[0] – TxINT. (Also Tx DMA hand shake at I/O pins)
The general function of this bit is to indicate that the TxFIFO has an
at least one empty space for data. The particular meaning of the bit
is controlled by MR0 [5:4] indicates the TxFIFO may be loaded with
one or more characters. If MR0[5:4] = 00 (the default condition) this
bit will not set until the TxFIFO is empty—256 bytes available. If the
fill level of the TxFIFO is below the trigger level programmed by the
TxINT field of the Mode Register 0, this bit will be set. A one in this
position indicates that at least one character can be sent to the
TxFIFO. It is turned off as the TxFIFO is filled above the level
programmed by MR0[5:4. This bit turns on as the FIFO empties.
(Note that the RxFIFO bit turns on as the FIFO fills.) This often a
point of confusion in programming interrupt functions for the receiver
and transmitter FIFOs.
ISR[5] – Address Recognition Status Change.
This bit is set when a change in receiver state has occurred due to
an Address character being received from an external source and
matches the reference address in ARCR. The bit and interrupt is
negated by a write to the CR with command x11011, Reset Address
Recognition Status.
ISR[4] – Xon/Xoff Status Change.
This bit is set when a Xon/Xoff character being received from an
external source. The bit is negated by a read of the channel
Xon/Xoff Interrupt Status Register, XISR.
ISR[3] – Counter Timer Status
The C/T has timed out or the count passed through 0. This bit is
cleared by issuing the ‘stop C/T ’ command.
NOTE: This bit must be at a one (1) for the transmitter to enter the
arbitration process. It is the fact that this bit is zero (0) when the
TxFIFO is full that stops a full TxFIFO from entering the interrupt
arbitration. Also note that the meaning if this bit is not quite the same
as the similar bit in the status register (SR).
ISR[2] – Change in Channel Break Status.
This bit, when set, indicates that the receiver has detected the
beginning or the end of a received break. It is reset when the CPU
issues a reset break change interrupt command via the CR.
2005 Nov 01
28
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
IMR – Interrupt Mask Register A and B
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
I/O Port Change of state
Rx Watch-dog
Time-out
Address
recognition event
Xon/off
event
C/T
Ready
Break Change
Of State
RxRDY
interrupt
TxRDY
interrupt
IMR[4] Xon/Xoff Enable
Enables the generation of an interrupt in response to recognition of
an in-band flow control character.
The programming of this register selects which bits in the ISR cause
an interrupt output. If a bit in the ISR is a ’1’ and the corresponding
bit in the IMR is a ’1’, the interrupt source is presented to the internal
interrupt arbitration circuits, eventually resulting in the IRQN output
being asserted (low). If the corresponding bit in the IMR is a zero,
the state of the bit in the ISR has no affect on the IRQN output.
IMR[3] Counter/Timer Enable
Enable the C/T interrupt when the C/T reaches 0 count.[2] Enables
the generation of an interrupt when a Break condition has been
detected by the channel receiver.
IMR[7] COS enable
Allows a change of state in the inputs equipped with input change
detectors to cause an interrupt.
IMR[1] Receiver (Rx) Enable
Enables the generation of an interrupt when servicing for the
RxFIFO is desired.
IMR[6] Fixed Watchdog Enable
Controls the generation of an interrupt watchdog timer event. If set,
a count of 64 idle bit times in the receiver will begin interrupt
arbitration.
IMR[0] Transmitter (Tx) Enable
Enables the generation of an interrupt when servicing for the
TxFIFO is desired.
IMR[5] Address recognition enable
Enables the generation of an interrupt in response to changes in the
Address Recognition circuitry of the Special Mode (multi-drop or
wake-up mode).
RxFIFO – Receiver FIFO, A and B
Bit[10]
Bit[9]
These bits are sent to the status register
Break
Framing
Received Status
Error Status
Bit[8]
Bits [7:0]
This the data byte sent to the data bus on RxFIFO read
8 data bits
MSBs =0 for 7,6,5 bit data
Parity
Error Status
The FIFO for the receiver is 11 bits wide and 256 ‘words’ deep. The
status of each byte received is stored with that byte and is moved
along with the byte as the characters are read from the FIFO. The
upper three bits are presented in the STATUS register and they
change in the status register each time a data byte is read from the
FIFO. Therefor the status register should be read BEFORE the byte
is read from the RxFIFO if one wishes to ascertain the quality of the
byte.
The foregoing applies to the ‘character error’ mode of status
reporting. See MR1[5] and ‘RxFIFO Status’ descriptions for ‘block
error’ status reporting. Briefly, ‘Block Error’ gives the accumulated
error of all bytes received by the RxFIFO since the last ‘Reset Error’
command was issued. (CR = 0x04)
TxFIFO – Transmitter FIFO, A and B
Bits 7:0
8 data bits. MSBs are ignored to 0 for 7, 6, 5 bit data
The FIFO for the transmitter is 8 bits wide by 256 bytes deep. For character lengths less than 8 bits the upper bits will be ignored by the
transmitter state machine and thus are effectively discarded.
RxFIL – Receiver FIFO Interrupt Level, A and B
Bits 7:0
Any one of 256 FIFO fill positions
The position in the Rx FIFO that causes the receiver will enter the interrupt arbitration process. This register is used to offset the effect of the
arbitration threshold. It use may yield moderate improvements in the interrupt service. It will also ‘equalize’ interrupt latency and allow for larger
aggregate block transfers between fast and slow channels. Writing to this register removes the interrupt control established in MR0 and MR1.
RxFL – Receiver FIFO Fill Level Register
Bits 7:0
Channel byte count code ** (1) = implied ‘1’
00000001 = 1
00000010 = 2
to
11111111 = 255
**(1)00000000 = 256 if RxRDY status bit is set.
The number of bytes filled in the receiver FIFO
2005 Nov 01
29
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
TxFIL – Transmitter FIFO Interrupt Level A and B
Bits 7:0
Any one of 256 FIFO empty positions
The position in the Tx FIFO that caused the transmitter will enter the interrupt arbitration process. This register is used to offset the effect of the
arbitration threshold. It use may yield moderate improvements in the interrupt service. It will also ‘equalize’ interrupt latency and allow for larger
aggregate block transfers between fast and slow channels. Writing to this register removes the interrupt control established in MR0 and MR1.
TxEL – Transmitter FIFO Empty Level Register
Bits 7:0
Channel byte count code ** (1) = implied ‘1’
00000001 = 1
00000010 = 2
to
11111111 = 255
**(1)00000000 = 256 if TxRDY status bit is set.
The number of empty bytes in the Transmitter FIFO.
Registers for Character Recognition
Please not that, although the names of the registers imply a particular function, there is not any hardware function directly attached to them.
They are just three characters that may be used for any function requiring recognition or simple character stripping.
It is only when other internal logic is enabled that the reception of a recognized character will trigger particular chip functions and/or interrupts.
XonCR – Xon/Xoff Character Register A and B
Bits 7:0
8 Bits of the Xon Character Recognition (Resets to 0x11)
An 8-bit character register that contains the compare value for a Xon character.
XoffCR – Xoff Character Register A and B
Bits 7:0
8 Bits of the Xoff Character Recognition (Resets to 0x13)
An 8-bit character register that contains the compare value for a Xoff character.
ARCR – Address Recognition Character Register A and B
Bits 7:0
8 Bits of the Multi-Drop Address Character Recognition (Resets to 0x00)
An 8 bit character register that contains the compare value for the wake-up address character.
2005 Nov 01
30
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
XISR – Xon–Xoff Interrupt Status Register A and B (Reading this register clears XISR(7:4))
Bits 7:6
Bits 5:4
Bits 3:2
Bits 1:0
Received X Character Status
Automatic X Character transmission
status
TxD flow status
TxD character status
00 = none
01 = Xoff received
10 = Xon received
11 = both received
00 = none
01 = Xon transmitted
10 = Xoff transmitted
11 = Both transmitted
00 = normal transmission
01 = TxD halt pending
10 = re-enabled
11 = flow halted
00 = normal TxD data
01 = Idle wait for FIFO
data
10 = Xoff in pending
11 = Xon in pending
• 10 – re–enabled. The transmitter had been halted and has been
XISR[7:6] Received X Character Status.
This field can be read to determine if the receiver has encountered a
Xon or Xoff character in the incoming data stream. These bits are
maintained until a read of the XISR. The field is updated by X
character reception regardless of the state of MR3(7) and MR3(3:2)
or IMR(4). The field can therefore be used as a character detector
for the bit patterns stored in the Xon and Xoff Character Registers.
restarted. It is sending (or is prepared to send) data characters.
After a read of the XISR, it will return to ‘normal’ status.
• 11 – The transmitter is stopped due to an Xoff character being
received from its associated receiver. The transmitter is ‘flow
controlled’.
XISR[5:4] Automatic transmission Status.
This field indicates the last flow control character sent in the Auto
Receiver flow control mode. If Auto Receiver mode has not been
enabled, this field will always read b’00. It will likewise reset to b’00 if
MR0(3) is reset. If the Auto Receiver mode is exited while this field
reads b’10, it is the user’s responsibility to transmit a Xon, when
appropriate.
XISR[1:0] TxD X character Status.
This field allows determination of the type of character being
transmitted. It will always be b’00 if none of the automatic X
character controls of MR3[3:2] is enabled.
• 01 – The channel is waiting for a data character to transfer from
the TxFIFO. This condition will only occur for a bit time after a Xon
or Xoff character transmission unless the TxFIFO is empty.
XISR[3:2] TxD Condition of the automatic flow control status.
This field tracks the transmitter’s flow status as follows:
• 10 – A command to send an Xoff character is pending.
• 11 – A command to send an Xon character is pending.
• 00 – normal transmission. Transmitter is not affected by Xon or
Xoff.
• 01 – TxD halt pending. After the current character finishes the
Conditions b’10 and b’11 will not exist for more than a character
time.
transmitter will stop. The status will then change to b’11.
WCXER Watch Dog, Character, Address and X Enable Register – A and B
Bit 7
Bit 6
Watch dog *
1 = disable Wd
0 = no action
1 = enable
Wd
0 = no action
Bit 5
Bit 4
BIT 3
Address recognition
Xon recognition
1 = disable Ar
0 = no action
1 = disable
Xon
0 = no action
1 = enable Ar
0 = no action
BIT 1
BIT 0
Xoff Recognition
1 = enable
Xon
0 = no action
1 = disable
Xoff
0 = no action
1 = enable
Xoff
0 = no action
causing any Xon/Xoff or wakeup mode activities to occur. The
recognition event is reported in the ISR register.
This register enables the UART’s Character Recognition, Address
Recognition and Receiver watchdog timer. If both enable and
disable are active a disable results. This register is used to enable
the general–purpose character recognition feature WITHOUT
2005 Nov 01
BIT 2
* This bit control is duplicated at MR0[7].
31
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Programmable Counters, Timers and Baud Rate generators
PBRGPU – Programmable BRG Timer Reload Registers, Upper 0 and 1
Bits 7:0
8 MSBs of the BRG Timer divisor.
This is the upper byte of the 16–bit value used by the BRG timer in generating a baud rate clock
PBRGPL – Programmable BRG Timer Reload Registers, Lower 0 and 1
Bits 7:0
8 LSB of the BRG Timer divisor.
This is the lower byte of the 16–bit value used by the BRG timer in generating a baud rate clock.
CTCS 0 and 1 – Counter Timer clock source
NOTE: Writing to this register removes the control established in the counter/timer portion of the ACR in the default register map
Bit 7:6
Reserved
Bit 5:4
Mode control
00 – Selects Counter Mode. Generates
a timing edge
Bit 3:0
Clock selection
0000 External I/O2 A (for CT 0), I/O7 A (for CT 1)
0001 External I/O2 A/16 (for CT 0), I/O7 A/16 (for CT 1)
0010 Sclk
0011 Sclk / 2
0100 Sclk / 16
0101 Sclk / 32
0110 Sclk / 64
0111 Sclk / 128
TxC1X A
TxC1X B
1010, 1011 Reserved
1100 Rx Character Count (Ch A) Clock is RxFIFO A load pulse
1101 Rx Character Count (Ch B) Clock is RxFIFO B load pulse
1110, 1111 Reserved
01 – Selects Timer Mode. Generates a
square wave
10 – Reserved
11 – Selects Timer Pulse Mode.
Generates periodic pulses twice the
frequency as in Timer Mode. Pulse width
is one cycle of the clock as it is delivered to
the C/T. (i.e. after any prescale)
CTVU – Counter Timer Value Registers, Upper 0 and 1
Bits 7:0
8 MSBs of the Counter timer preset value
Reading this register gives the value of the upper 8 bits of the counter timer.
CTVL – Counter timer Value Registers, Lower 0 and 1
Bits 7:0
8 LSB of the Counter timer preset value
Reading this register gives the value of the upper 8 bits of the
counter timer.
this could be made worse or completely eliminated. If the Stop
counter command is issued and following that the C/T is read there
will be no uncertainty go its value. If it is necessary to read the C/T
‘on the fly’ then reading it twice and comparing the values will
correct the problem. The double read will not be effective if the
counter timer clock is faster than a read cycle.
NOTE: The counter timer should be stopped before reading. Usually
the clock of the counter timer is not synchronized with the read of
the C/T. It is therefore possible to capture changing data during the
read. Depending on the clock speed with respect to the read cycle
PBRGCS – Programmable BRG Clock Source
Bit 7
PBRG 1, Register control
0 = Resets PBRG 1 and
holds it stopped
1 = Allows PBRG 1 to run.
Bit 6:4
PBRG 1, Clock selection
000 = Sclk
001 = Sclk / 2
010 = Sclk/ 16
011 = Sclk / 32
100 = Sclk / 64
101 = Sclk / 128
110 = I/O4 A
111 = Reserved
Bit 3
PBRG 0, Register control
0 = Resets PBRG 0 and
holds it stopped.
1 = Allows PBRG 0 to run.
receiver(s) or transmitter(s) the receivers and transmitters will
consider it as a 16x clock and further device it by 16. In other words
the receivers and transmitters will always be in the 16x ode of
operation when the internal BRG timer is selected for their clock.
Start/Stop control and clock select register for the two BRG
counters. The clock selection is for the input to the counters. It is
that clock divided by the number represented by the PBRGPU and
PBRGPL the will be used as the 16x clock for the receivers and
transmitters. When the BRG timer Clock is selected for the
2005 Nov 01
Bit 2:0
PBRG 0, Clock selection
000 = Sclk
001 = Sclk / 2
010 = Sclk / 16
011 = Sclk / 32
100 = Sclk / 64
101 = Sclk / 128
110 = I/O3 A
111 = Reserved
32
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
CTPU Counter Timer Preset Upper 0 and 1
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
The lower eight (8) bits for the 16 bit counter timer preset register
CTPU
BIT 2
BIT 1
BIT 0
BIT 2
BIT 1
BIT 0
CTPL Counter –Timer Preset Low 0 and 1
CTPL
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
The Upper eight (8) bits for the 16 bit counter timer preset register
the CPU. If I/O3 is programmed to be the output of the C/T, the
output remains high until terminal count is reached; at which time it
goes low. The output returns to the High State and ISR [3] is cleared
when the counter is stopped by a stop counter command. The CPU
may change the values of CTPU and CTPL at any time, but the new
count becomes effective only on the next start counter commands. If
new values have not been loaded, the previous count values are
preserved and used for the next count cycle
The CTPU and CTPL hold the eight MSBs and eight LSBs,
respectively, of the value to be used by the counter/timer in either
the counter or timer modes of operation. The minimum value that
may be loaded into the CTPU/CTPL registers is H‘0000’. Note that
these registers are write–only and cannot be read by the CPU.
In the timer mode, the C/T generates a square wave whose period is
twice the value (in C/T clock periods) of the CTPU and CTPL. The
waveform so generated is often used for a data clock. The formula
for calculating the divisor n to load to the CTPU and CTPL for a
particular 1X data clock is shown below.
In the counter mode, the current value of the upper and lower 8 bits
of the counter (CTPU, CTPL) may be read by the CPU. It is
recommended that the counter be stopped when reading to prevent
potential problems that may occur if a carry from the lower 8 bits to
the upper 8 bits occurs between the times that both halves of the
counter are read. However, note that a subsequent start counter
command will cause the counter to begin a new count cycle using
the values in CTPU and CTPL. When the C/T clock divided by 16 is
selected, the maximum divisor becomes 1,048,575.
The CTS, RTS, CTS Enable Tx signals
CTS (Clear To Send) is usually meant to be a signal to the
transmitter meaning that it may transmit data to the receiver. The
CTS input is on pin I/O0 A for Tx A and on I/O1 A for Tx B. The CTS
signal is active low; thus; it is called CTSN A for Tx A and CTSN B
for Tx B. RTS is usually meant to be a signal from the receiver
indicating that the receiver is ready to receive data. It is also active
low and is, thus, called RTSN A for Rx A and RTSN B for Rx B.
RTSN A is on pin I/O0 B and RTSN B is on I/O1 B. A receiver’s
RTSN output will usually be connected to the CTS input of the
associated transmitter. Therefore, one could say that RTS and CTS
are different ends of the same wire!
NOTE: The 2 in the denominator is for the Square wave generation.
For the Pulse mode change the 2 to a 1.
n+
(2
C/T clock input frequency
16
(Baud rate desired))
(If the pulse mode is selected, then ‘2’ in the divisor should be ‘1’.
This doubles the C/T output speeds for any given input clock.)
Often this division will result in a non–integer number, 26.3 for
example. One can only program integer numbers in a digital divider.
Therefore, 26 would be chosen. This gives a baud rate error of
0.3/26.3, which is 1.14% and well within the ability asynchronous
mode of operation.
If the value in CTPU and CTPL is changed, the current half–period
will not be affected, but subsequent half periods will be. The C/T will
not be running until it receives an initial ‘Start Counter’ command
from the command register (or a read at address A6–A0 = 0001110
in the lower 16 position address space) . After this, while in timer
mode, the C/T will run continuously. Receipt of a start counter
command causes the counter to terminate the current timing cycle
and to begin a new cycle using the values in CTPU and CTPL.
MR2 (4) is the bit that allows the transmitter to be controlled by the
CTS pin (I/O0 A or I/O1 A). When this bit is set to one AND the CTS
input is driven high, the transmitter will stop sending data at the end
of the present character being serialized. It is usually the RTS output
of the receiver that will be connected to the transmitter’s CTS input.
The receiver will set RTS high when the receiver FIFO is full AND
the start bit of the ninth character is sensed. Transmission then
stops with nine valid characters in the receiver. When MR2 (4) is set
to one, CTSN must be at zero for the transmitter to operate. If MR2
(4) is set to zero, the I/O pin will have no effect on the operation of
the transmitter. MR1 (7) is the bit that allows the receiver to control
I/O0 B. When the receiver controls I/O0 B (or I/O1 B), the meaning
of that pin will be the RTSN function.
The counter ready status bit (ISR [3]) is set once each cycle of the
square wave. The bit is reset by a stop counter command from the
command register (or a read with A6–A0 = 0x0F in the lower 16
position address space). The command however, does not stop the
C/T. the generated square wave is output on I/O3 if it is programmed
to be the C/T output. In the counter mode, the value C/T loaded into
CTPU and CTPL by the CPU is counted down to 0. Counting begins
upon receipt of a start counter command. Upon reaching terminal
count H‘0000’, the counter ready interrupt bit (ISR [3]) is set. The
counter continues counting past the terminal count until stopped by
2005 Nov 01
33
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Registers of the Arbitrating Interrupt System and Bidding control
ICR – Interrupt Control Register
Bits 7:0
Upper eight bits of the Arbitration Threshold
This register provides a single 8–bit field called the interrupt
threshold for use by the interrupt arbiter. The field is interpreted as a
single unsigned integer. The interrupt arbiter will not generate an
external interrupt request, by asserting IRQN, unless the value of
the highest priority interrupt exceeds the value of the interrupt
threshold. If the highest bidder in the interrupt arbitration is lower
than the threshold level set by the ICR, the Current Interrupt
Register, CIR, will contain 0x’00. Refer to the functional description
of interrupt generation for details on how the various interrupt source
bid values are calculated.
threshold value) to win interrupt arbitration without requiring the user
to explicitly lower the threshold level in the ICR. These bits are the
upper seven (8) bits of the interrupt arbitration system. The lower
three (3) bits represent the channel number.
UCIR – Update CIR
A command based upon a decode of address 0x61. (UCIR is not a
register!) A write (the write data is not important; a ‘don’t care’) to
this ’register’ causes the Current Interrupt Register to be updated
with the value that is winning interrupt arbitration. The register would
be used in systems that polls the interrupt status registers rather
than wait for interrupts. Alternatively, the CIR is normally updated
during an Interrupt Acknowledge Bus cycle in interrupt driven
systems.
NOTE: While a watch–dog Timer interrupt is pending, the ICR is not
used and only receiver codes are presented for interrupt arbitration.
This allows receivers with very low count values (perhaps below the
CIR – Current Interrupt Register
Bits 7:6
Bits 5:1
Bits 0
Type
Current byte count/type
Channel number or C/T number
00 = Type other than transmit or Receiver
00000 = no interrupt
00001 = Change of State
00010 = Address Recognition
00011 = Xon/Xoff status
00100 = Receiver Watch dog
00101 = Break change
00110 = Counter Timer
00111 = Rx Loop Back Error
0 = Channel A or C/T 0
1 = Channel B or C/T 1
01 = Transmit
11 = Receive w errors
10 = Receive w/o errors
Current count code
00000 => At least 1 character
00001 => At least 16 characters
00001 => At least 24 characters
.
.
11101 => At least 240 characters
11110 => At least 248 characters
11111 => 256 (See also GIBCR)
0=A
1=B
the CIR is updated. For most interrupting sources, the data available
in the CIR alone will be sufficient to set up a service routine.
The Current Interrupt Register is provided to speed up the
specification of the interrupting condition in the DUART. The CIR is
updated at the beginning of an interrupt acknowledge bus cycle or in
response to an Update CIR command. (see immediately above)
Although interrupt arbitration continues in the background, the
current interrupt information remains frozen in the CIR until another
IACKN cycle or Update CIR command occurs. The LSBs of the CIR
provide part of the addressing for various Global Interrupt registers
including the GIBCR, GICR, GITR and the Global RxFIFO and
TxFIFO FIFO. The host CPU need not generate individual
addresses for this information since the interrupt context will remain
stable at the fixed addresses of the Global Interrupt registers until
2005 Nov 01
The CIR may be processed as follows:
If CIR[7] = 1, then a receiver interrupt is pending and the count is
CIR[5:1], channel is CIR[0]
Else If CIR[6] = 1 then a transmitter interrupt is pending and the
count is CIR[5:1], channel is CIR[0]
Else the interrupt is another type, specified in CIR[5:1]
NOTE: The GIBCR, Global Interrupting Byte Count Register, may be
read to determine an exact character count.
34
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
IVR – Interrupt Vector Register
Bits 7:0
8 data bits of the Interrupt Vector (IVR)
The IVR contains the byte that will be placed on the data bus during an IACKN cycle when the GCCR bits (2:1) are set to binary ‘01’. This is the
unmodified form of the interrupt vector.
Modification of the IVR
Bits 7:3
Bits 2:1
Bit 0
Always contains bits (7:3) of the IVR
Will be replaced with current interrupt
type if IVC field of GCCR = 3
Replaced with interrupting channel
number if IVC field of GCCR > 1
The table above indicates how the IVR may be modified by the interrupting source. The modification of the IVR as it is presented to the data bus
during an IACK cycle is controlled by the setting of the bits (2:1) in the GCCR (Global Chip Configuration Register).
GICR – Global Interrupting Channel Register
Bits 7:1
Bit 0
Reserved
Channel code
0=a
1=b
A register associated with the interrupting channel as defined in the CIR. It contains the channel number for the interrupting channel.
GIBCR – Global Interrupting Byte Count Register
Bits 7:0
Channel byte count code
00000001 = 1
00000010 = 2
.
11111111 = 255
00000000 = 256
ready for transfer to the transmitter or transfer from the receiver. It is
undefined for other types of interrupts
A register associated with the interrupting channel as defined in the
CIR. Its numerical value equals TxEL or RxFL at the time IACKN or
‘Update CIR’ command was issued . The true number of bytes
GITR – Global Interrupting Type Register
Bit 7:6
Bit 5
Bit 4:3
Bit 2:0
Receiver Interrupt
Transmitter Interrupt
Reserved
Other types
0x = not receiver
10 = with receive errors
11 = w/o receive errors
0 = not transmitter
1 = transmitter interrupt
read 0x00
000 = not ‘other’ type
001 = Change of State
010 = Address Recognition Event
011 = Xon/Xoff status
100 = Rx Watchdog
101 = Break Change
110 = Counter Timer
111 = Rx Loop Back Error
A register associated with the interrupting channel as defined in the CIR. It contains the type of interrupt code for all interrupts.
GRxFIFO – Global RxFIFO Register
Bits 7:0
8 data bits of RxFIFO. MSBs set to 0 for 7, 6, 5 bit data
The RxFIFO of the channel indicated in the CIR channel field. Undefined when the CIR interrupt context is not a receiver interrupt. Global
TxFIFO Register
GTxFIFO – Global TxFIFO Register
Bits 7:0
8 data bits of TxFIFO. MSBs not used for 7, 6, 5 bit data
The TxFIFO of the channel indicated in the CIR channel field. Undefined when the CIR interrupt context is not a transmitter interrupt. Writing to
the GTxFIFO when the current interrupt is not a transmitter event may result in the characters being transmitted on a different channel than
intended.
2005 Nov 01
35
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
BCRBRK – Bidding Control Register – Break Change, A and B
Bits 7:0
MSBs of break change interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for a break change interrupt.
BCRCOS – Bidding Control Register – Change of State, A and B
Bits 7:0
MSBs of Change of state detectors (COS) interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for a Change of State, COS, interrupt.
BCRx – Bidding Control Register – Xon/Xoff, A and B
Bits 7:0
MSBs of an Xon/Xoff interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for a Xon/Xoff interrupt.
BCRA – Bidding Control Register – Address, A and B
Bits 7:0
MSBs of an address recognition event interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for an address recognition event interrupt.
BCR C/T – Bidding Control Register –C/T, 0 and 1
Bits 7:0
MSBs of a counter/timer event interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for a counter/timer event interrupt.
BCRLBE – Bidding Control Register – Received Loop Back Error
Bits 7:0
MSBs of a received loop back error event interrupt bid
This register provides the 8 MSBs of the Interrupt Arbitration number for the received loop back error interrupt.
Registers of the I/O ports
IPCRL – Input Port Change Register Lower Nibble, A and B (n = A for A, n = B for B)
Bit 7
Bit 6
Bit 7
Bit 6
Bit 3
Bit 2
Bit 1
Bit 0
∆I/O3 n
change
∆I/O2 n
change
∆I/O1 n
change
∆I/O0 n
change
I/O3 n state
I/O2 n state
I/O1 n state
I/O0 n
state
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
Reads the actual logic level at the pin.
1 = high level; 0 = low level
This register may be read to determine the current logical level of the I/O pins and examine the output of the change detectors assigned to each
pin. If the change detection is not enabled or if the pin is configured as an output, the associated change field will read b’0.
IPCRU – Input Port Change Register Upper Nibble, A and B (n = A for A, n = B for B)
Bit 7
Bit 6
Bit 7
Bit 6
Bit 3
Bit 2
Bit 1
Bit 0
∆I/O7 n change
∆I/O6 n change
∆I/O5 n change
∆I/O4 n change
I/O7 n state
I/0n6 state
I/O5 n state
I/O4 n state
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
Reads the actual logic level at the pin.
1 = high level; 0 = low level
This register may be read to determine the current logical level of the I/O pins and examine the output of the change detectors assigned to each
pin. If the change detection is not enabled or if the pin is configured as an output, the associated change field will read b’0.
IPR – Input Port Register, A and B (n = A for A, n = B for B)
Bits 7:0
Logical levels of I/O(7:0)n
2005 Nov 01
36
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
IPCE – Input Change Detect Enable, A and B (n = A for A, n = B for B)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
∆I/O7 n enable
∆I/O6 n enable
∆I/O5 n enable
∆I/O4 n enable
∆I/O3 n enable
∆I/O2 n enable
∆I/O1 n enable
∆I/O0 n enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
0 = disable
1 = enable
IPCE[7:0] bits activate the input change of state detectors. If a pin is configured as an output, the change of state detectors, if enabled, continue
to be active and will show a change of state as the I/P port changes.
I/OPCR 0 – I/O Port Configuration Register
Bits 7:6
Bits 5:4
Bits 3:2
Bits 1:0
I/O3 A control
I/O2 A control
I/O1 A control
I/O0 A control
00 = GPI / TxC A
01 = OPR[3] A
10 = TxC A (16X) Output
11 = Reserved
00 = GPI / CT 0 Clock Input
01 = OPR[2] A / DTRN A
10 = TxC A (1X) Output
11 = Reserved
00 = GPI / CTSN B
01 = OPR[1] A
10 –
11 = Reserved
00 = GPI / CTSN A
01 = OPR[0] A
10 –
11 = Reserved
I/OPCR 1 – I/O Port Configuration Register
Bits 7:6
Bits 5:4
Bits 3:2
Bits 1:0
I/O7 A control
I/O6 A control
I/O5 A control
I/O4 A control
00 = GPI / CT 1 Clock Input
01 = OPR[7] A / DTRN B
10 = TxC B (1X) Output
11 = Reserved
00 = GPI / RxC B / PBRG 1 Clk Input
01 = OPR[6] A
10 = RxC B (16X) Output
11 = Reserved
00 = GPI / TxC B
01 = OPR[5] A
10 = TxC B (16X) Output
11 = Reserved
00 = GPI / RxC A / PBRG 0 Clk Input
01 = OPR[4] A
10 = RxC A (16X) Output
11 = Reserved
I/OPCR 2 – I/O Port Configuration Register
Bits 7:6
Bits 5:4
Bits 3:2
Bits 1:0
I/O3 B control
I/O2 B control
I/O1 B control
I/O0 B control
00 = GPI /DSRN B
01 = OPR[3] B
10 = RxC B (1X) Output
11 = C/T 0 Output (open
drain)
00 = GPI /DSRN A
01 = OPR[2] B
10 = RxC A (1X) Output
11 = C/T 1 Output (open drain)
00 = GPI
01 = OPR[1] B / RTSN B
10 = Reserved
11 = Reserved
00 = GPI
01 = OPR[0] B / RTSN B
10 = Reserved
11 = Reserved
I/OPCR 3 – I/O Port Configuration Register
Bits 7:6
Bits 5:4
Bits 3:2
Bits 1:0
I/O7 B control
I/O6 B control
I/O5 B control
I/O4 B control
00 = GPI /RIN B
01 = OPR[7] B
10 =TxINTN B (open drain)
11 =reserved
00 = GPI /RIN A
01 = OPR[6] B
10 =TxINTN A (open drain)
11 = reserved
00 = GPI /DCDN B
01 = OPR[5] B
10 = RxINTN B (open
drain)
11 = reserved
00 = GPI /DCDN A
01 = OPR[4] B
10 = RxINTN A (open drain)
11 = reversed
NOTE: Both I/O Port A and B default to input upon a hardware reset to avoid hardware conflicts with I/O direction
The four registers above contain 4, 2 bit fields that set the direction and source for each of the I/O pins associated with the channel. The I/O0 B
or I/O1 B output may be RTSN if MR1[7] is set. It may also signal ‘end of transmission’ if MR2[5] is set. (Please see the descriptions of these
functions under the MR1 and MR2 register descriptions).
The binary settings of the binary 00 combination always configures the I/O pins as ‘inputs’. However the input circuit of the I/O pins are ALWAYS
active. In actuality the binary 00 condition only disable the output driver of the pin. Since the input circuit and the associated change of state
detector is always active the output signal may generate interrupts or drive counters.
This register resets to 0x00 on reset, effectively configuring all I/O pins as inputs. Inputs may be used as RxC, TxC inputs or CTSN and General
Purpose Inputs simultaneously. All inputs are equipped with change detectors that may be used to generate interrupts or can be polled, as
required.
2005 Nov 01
37
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
SOPR A and SOPR B – Set the Output Port Bits (OPR A and OPR B)
SOPR [7:0] – Ones in the byte written to this register will cause the corresponding bit positions in the OPR to set to 1. Zeros have no effect. This
allows software to set individual bits with our keeping a copy of the OPR bit configuration. One register for each channel.
Set OPR Bits
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
OPR 7
OPR 6
OPR 5
OPR 4
OPR 3
OPR 2
OPR 1
OPR 0
1=set bit
0=no
change
1=set bit
0=no
change
1=set bit
0=no
change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no
change
ROPR A and ROPR B – Reset ROPR Output Port Bits (OPR A and OPR B)
ROPR [7:0] – Ones in the byte written to the ROPR will cause the corresponding bit positions in the OPR to set to 0. Zeros have no effect. This
allows software to reset individual bits with our keeping a copy of the OPR bit configuration. One register for each channel
Reset OPR
Bits
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
OPR 7
OPR 6
OPR 5
OPR 4
OPR 3
OPR 2
OPR 1
OPR 0
1=reset bit
0=no change
1=reset bit
0=no
change
1=reset bit
0=no
change
1=reset bit
0=no
change
1=reset bit
0=no
change
1=reset bit
0=no
change
1=reset bit
0=no
change
1=reset bit
0=no change
OPR – Output Port Register, A and B (n = A for A, n = B for B)
The output pins (I/O pins) drive the data written to this register.
OPR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
I/O7 n
I/O6 n
I/O5 n
I/O4 n
I/O3 n
I/O2 n
I/O1 n
I/O0 n
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
This register is set by the SOPR and ROPR above.
2005 Nov 01
38
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
THE REGISTERS FOR COMPATIBILITY WITH PREVIOUS DUARTS
to C92’ command be issued before calling code written for older
devices. This is just recommended. If one wishes to enhance
previous code by using Xon/Xoff, for example, there is no restriction
against it. These registers provide the original functionality of
previous Philips DUARTs: SCN2681, SCN68681, SCC2691,
SCC68692, SC26C92 and SC28L92.
The purpose of including previous functionality is to allow users to
call communications code that may be used in former systems.
When the registers in this lower 16–position address space is used
it will revoke programming done in the upper address space where
the addresses are duplicated. If functions have been called from
upper address space that DO NOT exist in the lower address space
they will remain active. It is therefore recommended that the ‘Reset
Table 7. SC28L92 Register Addressing READ (RDN = 0) WRITE (WRN = 0)
Address
READ (RDN = 0)
WRITE (WRN = 0)
0
0
0
0
Mode Register A (MR0 A, MR1 A, MR2 A)
Mode Register A (MR0 A, MR1 A, MR2 A)
0
0
0
1
Status Register A (SR A)
Clock Select Register A (CSR A )
0
0
1
0
Reserved
Command Register A (CR A)
0
0
1
1
Rx Holding Register A (RxFIFO A)
Tx Holding Register A (TxFIFO A)
0
1
0
0
Input Port Change Register (IPCR)
Aux. Control Register (ACR)
0
1
0
1
Interrupt Status Register (ISR)
Interrupt Mask Register (IMR)
0
1
1
0
Counter/Timer Upper (CTPU)
C/T Upper Preset Register (CTPU)
0
1
1
1
Counter/Timer Lower (CTPL)
C/T Lower Preset Register (CTPL)
1
0
0
0
Mode Register B (MR0 B, MR1 B, MR2 B)
Mode Register B (MR0 B, MR1 B, MR2 B)
1
0
0
1
Status Register B (SR B)
Clock Select Register B (CSR B )
1
0
1
0
Reserved
Command Register B (CR B)
1
0
1
1
Rx Holding Register B (RxFIFO B)
Tx Holding Register B (TxFIFO B)
1
1
0
0
IVR or general purpose register
IVR or general purpose register
1
1
0
1
Input Port (IPR) I/O(6:0) A
Output Port Confide. Register (OPCR) I/O(7:2) B
1
1
1
0
Start Counter Command (C/T 0)
Set Output Port Bits Command (SOPR) I/O(7:0) B
1
1
1
1
Stop Counter Command (C/T 0)
Reset output Port Bits Command (ROPR) I/O(7:0) B
NOTE: The three MR Registers are accessed via the MR Pointer and Commands 0x1n and 0xBn (where n = represents receiver and
transmitter enable bits)
The following registers are unique for each Channel
These registers support functions for both Channels
Mode Register
MRn A
MRn B
R/W
Input Port Change Register
IPCR
R
Status Register
SR A
SR B
R only
Auxiliary Control Register
ACR
W
Clock
Select
CSR A
CSR B
W only
Interrupt Status Register
ISR
R
Interrupt Mask Register
IMR
W
Command
Register
CR A
Counter Timer Upper Value
CTPU
R
Counter Timer Lower Value
CTPL
R
Counter Timer Preset Upper
CTPU
W
Counter Timer Preset Lower
CTPL
W
Input Port Register
IPR
R
Output Configuration Register
OPCR
W
Set Output Port
Bits
W
Reset Output Port
Bits
W
CR B
W only
Receiver
FIFO
RxFIFO A
RxFIFO B
R only
Transmitter
FIFO
TxFIFO A
TxFIFO B
W only
2005 Nov 01
39
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Table 8. Baud Rate Generator Characteristics
Crystal or Clock = 14.7456 MHz
NORMAL RATE
(BAUD)
ACTUAL 16X
CLOCK (kHz)
ERROR (%)
NORMAL RATE
(BAUD)
ACTUAL 16X
CLOCK (kHz)
ERROR (%)
50
0.8
0
2400
38.4
0
75
1.2
0
4800
76.8
0
110
1.759
–0.069
7200
115.2
0
134.5
2.153
0.059
9600
153.6
0
150
2.4
0
19.2K
307.2
0
200
3.2
0
38.4K
614.4
0
300
4.8
0
14.4K
230.4
0
600
9.6
0
28.8K
460.8
0
1050
16.756
–0.260
31.25
500.0
1.6
1200
19.2
0
57.6k
921.6
0
1800
28.8
0
115.2K
1843.2
0
2000
32.056
0.175
230.4K
3686.4
0
NOTE: Duty cycle of 16X clock is 50% ± 1%
2005 Nov 01
40
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REGISTER DESCRIPTIONS Mode Registers
MR0 Mode Register 0 MR0 is accessed by setting the MR pointer to 0 via the command register command B.
MR0 A
MR0 B
MR0 B[3:0]
are reserved
Bit 7
BIT 6
BIT (5:4)
BIT 3
BIT 2
BIT 1
BIT 0
Rx WATCH
DOG
0 = Disable
1 = Enable
RxINT BIT 2
See Tables in
MR0 description
TxINT (1:0)
See table #4
FIFO Size
0=8
1 = 256
BAUD RATE
EXTENDED II
0 = Norma
1 = Extend II
TEST 2
Set to 0
BAUD RATE
EXTENDED 1
0 = Normal
1 = Extend
MR0[5:4] – Tx interrupt fill level.
MR0[7] This bit controls the receiver watchdog timer. 0 = disable,
1 = enable. When enabled, the watch dog timer will generate a
receiver interrupt if the receiver FIFO has not been accessed within
64 bit times of the receiver 1X clock. This is used to alert the control
processor that data is in the RxFIFO that has not been read. This
situation may occur when the byte count of the last part of a
message is not large enough to generate an interrupt. This control
bit is duplicated WCXER(7:6)
Table 11. Transmitter FIFO Interrupt Fill Level
MR0[3] = 0
MR0[5:4]
00
01
10
11
MR0[6] – Bit 2 of receiver FIFO interrupt level. This bit along with Bit
6 of MR1 sets the fill level of the 8 byte FIFO that generates the
receiver interrupt.
Table 12. Transmitter FIFO Interrupt Fill Level
MR0[3] = 1
MR0[6] MR1[6] Note that this control is split between MR0 and MR1.
This is for backward compatibility to the SC2692 and SCN2681.
MR0[5:4]
00
01
10
11
Table 9. Receiver FIFO Interrupt Fill Level
MR0[3] = 0
MR0[6] MR1[6]
Interrupt Condition
00
1 or more bytes in FIFO (Rx RDY)
01
3 or more bytes in FIFO
10
6 or more bytes in FIFO
11
8 bytes in FIFO (Rx FULL)
Interrupt Condition
8 bytes empty (Tx EMPTY)
4 or more bytes empty
6 or more bytes empty
1 or more bytes empty (Tx RDY)
Interrupt Condition
256 bytes empty (Tx EMPTY)
128 or more bytes empty
192 or more bytes empty
1 or more bytes empty (Tx RDY)
For the transmitter these bits control the number of FIFO positions
empty when the receiver will attempt to interrupt. After the reset the
transmit FIFO has 8 bytes empty. It will then attempt to interrupt as
soon as the transmitter is enabled. The default setting of the MR0
bits (00) condition the transmitter to attempt to interrupt only when it
is completely empty. As soon as one byte is loaded, it is no longer
empty and hence will withdraw its interrupt request.
Table 10. Receiver FIFO Interrupt Fill Level
MR0[3] = 1
MR0[6] MR1[6]
Interrupt Condition
MR0[3] – FIFO Size
00
1 or more bytes in FIFO (Rx RDY)
01
128 or more bytes in FIFO
MR0[2:0] – These bits are used to select one of the six–baud rate
groups.
10
192 or more bytes in FIFO
See Table 13 for the group organization.
11
256 bytes in FIFO (Rx FULL)
• 000 Normal mode
• 001 Extended mode I
• 100 Extended mode II
For the receiver these bits control the number of FIFO positions
empty when the receiver will attempt to interrupt. After the reset the
receiver FIFO is empty. The default setting of these bits cause the
receiver to attempt to interrupt when it has one or more bytes in it.
Other combinations of MR2[2:0] should not be used
NOTE: MR0[3:0] are not used in channel B and should be set to ‘0’.
2005 Nov 01
41
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
MR1 Mode Register 1
MR1 A
MR1 B
Bit 7
BIT 6
BIT 5
Bit (4:3)
BIT 2
Bits (1:0)
Rx
CONTROLS
RTS
RxINT
BIT 1
ERROR
MODE
PARITY MODE
PARITY
TYPE
BITS PER
CHARACTER
0 = No
1 = Yes
0 = RxRDY
1 = FFULL
0 = Char
1 = Block
0 = Even
1 = Odd
00 = 5
01 = 6
10 = 7
11 = 8
00 = With Parity
01 = Force Parity
10 = No Parity
11 = Multi–drop Mode
NOTE: * In block error mode the block error conditions must be cleared by using the error reset command (command 0x40) or a receiver reset.
MR1 A is accessed when the Channel A MR pointer points to MR1.
The pointer is set to MR1 by RESET or by a ‘set pointer’ command
applied via CR command 1. After reading or writing MR1 A, the
pointer will point to MR2 A.
mode, the status provided in the SR for these bits is the
accumulation (logical–OR) of the status for all characters coming to
the top of the FIFO since the last ‘reset error’ command for Channel
A was issued.
MR1 A[7] – Channel A Receiver Request–to–Send Control (Flow
Control)
This bit controls the deactivation of the RTSN A output (I/O0 B) by
the receiver. This output is normally asserted by setting OPR[0]B
and negated by resetting OPR[0]B.
MR1 A[4:3| – Channel A Parity Mode Select
If ‘with parity’ or ‘force parity’ is selected a parity bit is added to the
transmitted character and the receiver performs a parity check on
incoming data
MR1 A[4:3] = 11 selects Channel A to operate in the special
multi–drop mode described in the Operation section.
MR1 A[7] = 1 causes RTSN A to be negated (I/O0 B is driven to a ‘1’
[VCC]) upon receipt of a valid start bit if the Channel A FIFO is full.
This is the beginning of the reception of the ninth byte. If the FIFO is
not read before the start of the tenth byte, an overrun condition will
occur and the tenth byte will be lost. However, the bit in OPR[0] is
not reset and RTSN A will be asserted again when an empty FIFO
position is available. This feature can be used for flow control to
prevent overrun in the receiver by using the RTSN A output signal to
control the CTSN input of the transmitting device.
MR1 A[2] – Channel A Parity Type Select
Selects the parity type (odd or even) if the ‘‘with parity’ mode is
programmed by MR1 A[4:3], and the polarity of the forced parity bit if
the ‘force parity’ mode is programmed; no effect if ‘no parity’ is
programmed. In the special multi–drop mode it selects the polarity of
the A/D bit.
MR1 A[1:0] – Channel A Bits Per Character Select
This field selects the number of data bits per character to be
transmitted and received. The character length does not include the
start, parity, and stop bits.
MR1[6] – Receiver interrupt control bit 1. See description under
MR0[6].
MR1 A[5] – Channel A Error Mode Select
This bit select the operating mode of the three FIFOed status bits
(FE, PE, received break) for Channel A. In the ‘character’ mode,
status is provided on a character–by–character basis; the status
applies only to the character at the top of the FIFO. In the ‘block’
MR2 A is accessed when the Channel A MR pointer points to MR2,
which occurs after any access to MR1 A. Accesses to MR2 A do not
change the pointer.
MR2 Mode Register 2
Bit 7
MR2 A
MR2 B
BIT 6
BIT 5
BIT 4
BIT 3
CHANNEL MODE
Tx CONTROLS RTS
CTS
ENABLE Tx
STOP BIT LENGTH
NOTE: Add 0.5 to binary codes 0 – 7 for 5 bit character lengths.
00 = Normal
01 = Auto–Echo
10 = Local loop
11 = Remote loop
0 = No
1 = Yes
0 = No
1 = Yes
0 = 0.563 4 = 0.813 8 = 1.563 C = 1.813
1 = 0.625 5 = 0.875 9 = 1.625 D = 1.875
2 = 0.688 6 = 0.938 A = 1.688 E = 1.938
3 = 0.750 7 = 1.000 B = 1.750 F = 2.000
NOTE: *Add 0.5 to values shown for 0 – 7 if channel is programmed for 5 bits/char.
See description in the previous MR2 description
2005 Nov 01
42
BIT 2
BIT 1
BIT 0
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
SR Status Register
SR A
SR B
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RECEIVED
BREAK*
FRAMING
ERROR*
PARITY
ERROR*
OVERRUN
ERROR
TxEMT
TxRDY
FFULL
RxRDY
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
NOTE: *These status bits are appended to the corresponding data character in the receive FIFO. A read of the status provides these bits
(7:5) from the top of the FIFO together with bits (4:0). These bits are cleared by a ‘reset error status’ command. In character mode they are
discarded when the corresponding data character is read from the FIFO. In block error mode, the error–reset command (command 4x or
receiver reset) must used to clear block error conditions
SR A[7] – Received Break
Channel A Received Break. This bit indicates that an all zero
character of the programmed length has been received without a
stop bit. Only a single FIFO position is occupied when a break is
received: further entries to the FIFO are inhibited until the RxD A line
returns to the marking state for at least one–half a bit time two
successive edges of the internal or external 1X clock. This will
usually require a high time of one X1 clock period or 3 X1 edges
since the clock of the controller is not synchronous to the X1 clock.
SR A[3] – Channel A Transmitter Empty (TxEMT A)
This bit will be set when the transmitter under runs, i.e., both the
TxEMT and TxRDY bits are set. This bit and TxRDY are set when
the transmitter is first enabled and at any time it is re–enabled after
either (a) reset, or (b) the transmitter has assumed the disabled
state. It is always set after transmission of the last stop bit of a
character if no character is in the THR awaiting transmission.
It is reset when the THR is loaded by the CPU, a pending
transmitter disable is executed, the transmitter is reset, or the
transmitter is disabled while in the under run condition.
When this bit is set, the Channel A ‘change in break’ bit in the ISR
(ISR[2]) is set. ISR[2] is also set when the end of the break
condition, as defined above, is detected.
SR A[2] – Channel A Transmitter Ready (TxRDY A)
This bit, when set, indicates that the transmit FIFO is not full and
ready to be loaded with another character. This bit is cleared when
the transmit FIFO is loaded by the CPU and there are (after this
load) no more empty locations in the FIFO. It is set when a
character is transferred to the transmit shift register. TxRDY A is
reset when the transmitter is disabled and is set when the
transmitter is first enabled. Characters loaded to the TxFIFO while
this bit is 0 will be lost. This bit has different meaning from ISR[0].
The break detect circuitry can detect breaks that originate in the
middle of a received character. However, if a break begins in the
middle of a character, it must persist until at least the end of the next
character time in order for it to be detected.
This bit is reset by command 4 (0100) written to the command
register or by receiver reset.
SR A[6] – Channel A Framing Error
This bit, when set, indicates that a stop bit was not detected when
the corresponding data character in the FIFO was received. The
stop bit check is made in the middle of the first stop bit position.
SR A[1] – Channel A FIFO Full (FFULL A)
This bit is set when a character is transferred from the receive shift
register to the receive FIFO and the transfer causes the FIFO to
become full, i.e., all eight FIFO positions are occupied. It is reset
when the CPU reads the receive FIFO. If a character is waiting in
the receive shift register because the FIFO is full, FFULL A will not
be reset when the CPU reads the receive FIFO. This bit has
different meaning from ISR1 when MR1 6 is programmed to a ‘1’.
SR A[5] – Channel A Parity Error
This bit is set when the ‘with parity’ or ‘force parity’ mode is
programmed and the corresponding character in the FIFO was
received with incorrect parity.
In the special multi–drop mode the parity error bit stores the receive
A/D (Address/Data) bit.
SR A[0] – Channel A Receiver Ready (RxRDY A)
This bit indicates that a character has been received and is waiting
in the FIFO to be read by the CPU. It is set when the character is
transferred from the receive shift register to the FIFO and reset
when the CPU reads the receive FIFO, only if (after this read) there
are no more characters in the FIFO.
SR A[4] – Channel A Overrun Error
This bit, when set, indicates that one or more characters in the
received data stream have been lost. It is set upon receipt of a new
character when the FIFO is full and a character is already in the
receive shift register waiting for an empty FIFO position. When this
occurs, the character in the receive shift register (and its break
detect, parity error and framing error status, if any) is lost.
SR B – Channel B Status Register
The bit definitions for this register are identical to the bit definitions
for SR A, except that all status applies to the Channel B receiver
and transmitter and the corresponding inputs and outputs.
This bit is cleared by a ‘reset error status’ command.
2005 Nov 01
43
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
CSR A – Channel A Clock Select Register CSR A [7:4] – Channel A Receiver Clock Select
This field selects the baud rate clock for the Channel A receiver. The field definition is shown in Table 13.
CSR Clock Select Register
Bit 7
CSR A & CSR B
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
RECEIVER CLOCK SELECT
TRANSMITTER CLOCK SELECT
See Text and Table 13
See Text and Table 13
BIT 0
Table 13. Baud Rate (Base on a 14.7456 MHz crystal clock)
MR0[0] = 0 (Normal Mode)
MR0[0] = 1 (Extended Mode I)
MR0[2] = 1 (Extended Mode II)
CSR A [7:4]
ACR[7] = 0
ACR[7] = 1
ACR[7] = 0
ACR[7] = 1
ACR[7] = 0
ACR[7] = 1
0000
50
75
300
450
4,800
7,200
0001
110
110
110
110
880
880
0010
134.5
134.5
134.5
134.5
1,076
1,076
0011
200
150
1200
900
19.2K
14.4K
0100
300
300
1800
1800
28.8K
28.8K
0101
600
600
3600
3600
57.6K
57.6K
0110
1,200
1,200
7200
7,200
115.2K
115.2K
0111
1,050
2,000
1,050
2,000
1,050
2,000
1000
2,400
2,400
14.4K
14.4K
57.6K
57.6K
1001
4,800
4,800
28.8K
28.8K
4,800
4,800
1010
7,200
1,800
7,200
1,800
57.6K
14.4K
1011
9,600
9,600
57.6K
57.6K
9,600
9,600
1100
38.4K
19.2K
230.4K
115.2K
38.4K
19.2K
1101
Timer
Timer
Timer
Timer
Timer
Timer
1110
I/O4 A–16X
I/O4 A–16X
I/O4 A–16X
I/O4 A–16X
I/O4 A–16X
I/O4 A–16X
1111
I/O4 A–1X
I/O4 A–1X
I/O4 A–1X
I/O4 A–1X
I/O4 A–1X
I/O4 A–1X
NOTE: The receiver clock is always a 16X clock except for CSR A [7:4] = 1111.
CSR A [3:0] – Channel A EXTERNAL Transmitter Clock Select
This field selects the baud rate clock for the Channel A transmitter.
The field definition is as shown in Table 13, except as follows:
CSR A [3:0]
ACR[7] = 0
ACR[7] = 1
1110
I/O3 A–16X
I/O3 A–16X
1111
I/O3 A–1X
I/O3 A–1X
The receiver clock is always a 16X clock except for
CSR B[7:4] = 1111.
CSR B [3:0] – Channel B Transmitter Clock Select
This field selects the baud rate clock for the Channel B transmitter.
The field definition is as shown in Table 13, except as follows:
The transmitter clock is always a 16X clock except for
CSR[3:0] = 1111.
CSR B [7:4]
ACR[7] = 0
ACR[7] = 1
I/O6 A–16X
I/O6 A–16X
111
I/O6 A–1X
I/O6 A–1X
ACR[7] = 0
ACR[7] = 1
I/O5 A–16X
I/O5 A–16X
1111
I/O5 A–1X
I/O5 A–1X
The transmitter clock is always a 16X clock except for
CSR B[3:0] = 1111.
CSR B [7:4] – Channel B Receiver Clock Select
This field selects the baud rate clock for the Channel B receiver. The
field definition is as shown in Table 13, except as follows:
1110
CSR B [3:0]
1110
Rx FIFO Register. For characters shorter than 8 bits the unused bits are set to zero
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
BIT 2
BIT 1
BIT 0
Bits of the received data characters.
Tx FIFO register. For characters shorter than 8 bits the unused bits are set to zero
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
Bits of the data characters to be transmitted
2005 Nov 01
44
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
CR A and B Command Register
CR, one for each channel, controls the channel commands and enables/disables the receiver and transmitter. Commands may be to the upper
and lower four bits in the same bus cycle. If both enable and disable bits are set to 1 in the lower four bits a disable will result.
CR Command Register
Bit 7
CR A &CR B
BIT 3
BIT 2
BIT 1
BIT 0
MISCELLANEOUS COMMANDS
BIT 6
BIT 5
BIT 4
Disable Tx
Enable Tx
Disable Rx
Enable Rx
See Text of Channel Command Register
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
NOTE: Access to the miscellaneous commands should be separated by 3 X1 clock edges. A disabled transmitter cannot be loaded.
COMMAND REGISTER TABLE A and B
Commands 0xE, 0xF (marked with *) are global and exist only in channel A’s register space.
Channel Command Code
Channel Command
Channel Command Code
Channel Command
CR[7:4]
Description
CR[7:4]
Description
0000
NOP
1000
Assert RTSN (I/O0 B or I/O1 B)
0001
Set MR pointer to 1
1001
Negate RTSN (I/O0 B or I/O1 B)
0010
Reset Receiver
1010
Set C/T Receiver time–out mode on
0011
Reset Transmitter
1011
Set MR pointer to 0
0100
Reset Error Status
1100
Set C/T Receiver time–out mode off
0101
Reset Break Change Interrupt
1101
Block Error Status on RxFIFO load
0110
Begin Transmit Break
1110
• Power Down Mode On
0111
End Transmit Break
1111
• Disable Power Down Mode
• 0000 No command.
• 0001 set MR pointer to 1
• 0010 Reset receiver. Immediately resets the receiver as if
The transmitter must be enabled to start a break.
• 0111 Stop break. The TxD line will go high (marking) within two bit
times. TxD will remain high for one bit time before the next
character is transmitted.
• 1000 Assert RTSN. Causes the RTSN output to be asserted (low).
• 1001 Negate RTSN. Causes the RTSN output to be negated
hardware reset had been applied. The receiver is reset and the
FIFO pointer is reset to the first location effectively discarding all
unread characters in the FIFO.
• 0011 Reset transmitter. Immediately resets the transmitter as if a
(high).
hardware reset had been applied. The transmitter is reset and the
FIFO pointer is reset to the first location effectively discarding all
untransmitted characters in the FIFO.
NOTE: The two commands above actually reset and set,
respectively, the I/O0 B or I/O1 B pin associated WITH the
OPR register.
• 0100 Reset error status. Clears the received break, parity error,
• 1010 Set C/T Receiver time out mode on. The receiver in this
framing error, and overrun error bits in the status register
(SR[7:4]). I
channel will restart the C/T as reach receive character is
transferred from the shift register to the RxFIFO. The C/T is
placed in the Counter Mode, the Start/Stop Counter commands
are disabled, the counter is stopped and the Counter Ready bit,
ISR(3), is reset.
It is used in either character or block mode. In block mode it would
normally be used after the block is read.
• 0101 Reset break change interrupt. Causes the break detect
• 1011 Set MR Pointer to 0
• 1100 Set C/T Receiver time out mode off
• 1101 Block error status accumulation on FIFO entry. Allows the
change bit in the interrupt status register (ISR[2]) to be cleared to
zero.
• 0110 Start break. Forces the TxD output low (spacing). If the
transmitter is empty, the start of the break condition will be
delayed up to two bit times. If the transmitter is active and the
TxFIFO is empty then the break begins when transmission of the
current character is completed. If there are characters in the
TxFIFO, the start of break is delayed until all characters presently
in the TxFIFO and any subsequent characters loaded have been
transmitted. (Tx Idle must be true before break begins).
2005 Nov 01
‘received break’, ‘framing error’ and ‘parity error’ bits to be set as
the received character is loaded to the RxFIFO. (normally these
bits are set on reading of the data from the RxFIFO) Setting this
mode can give information about error data up to 256 bytes earlier
than the normal mode. However it clouds the ability to know
precisely which byte(s) are in error.
• 1110 Power Down Mode On
• 1111 Disable Power Down Mode
45
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
IPCR Input Port Configuration Register
IPCR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Delta
I/O 3A
Delta
I/O 2A
Delta
I/O 1A
Delta
I/O 0A
I/O 3A
I/O 2A
I/O 1A
I/O 0A
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
0 = no change
1 = change
0 = low
1 = High
0 = low
1 = High
0 = low
1 = High
0 = low
1 = High
IPCR [3:0] I/O3 A, I/O2 A, I/O1 A, I/O0 A logical level of I/O pin.
These bits provide the current state of the respective inputs. The
information is unlatched and reflects the state of the input pins at the
time the IPCR is read.
IPCR [7:4] I/03A, I/O2 A, I/O1 A, I/O0 A Change–of–State
These bits are set when a change–of–state, as defined in the input
port section of this data sheet, occurs at the respective input pins.
They are cleared when the IPCR is read by the CPU. A read of
the IPCR also clears ISR [7], the input change bit in the interrupt
status register. The setting of these bits can be programmed to
generate an interrupt to the CPU.
ACR Auxiliary Control Register
ACR
Bit 7
BIT 6
BRG SET
Select
0 = set 1
1 = set 2
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Counter Timer Mode
and
clock source select
Delta
I/O3 A interrupt
enable
Delta
I/O2 A interrupt
enable
Delta
I/O1 A interrupt
enable
Delta
I/O0 A interrupt
enable
See Table 14
0 = off
1 = enabled
0 = off
1 = enabled
0 = off
1 = enabled
0 = off
1 = enabled
ACR[7] – Baud Rate Generator Set Select
This bit selects one of two sets of baud rates to be generated by the
BRG and it effects both channels. (see Table 13).
Table 14. ACR 6:4 Field Definition
ACR[6:4] – Counter/Timer Mode And Clock Source Select
This field selects the operating mode of the counter/timer and its
clock source as shown in Table 14.
ACR[3:0] – I/O3 A, I/O2 A, I/O1 A, I/O0 A Change-of-State
Interrupt Enable
This field selects which bits of the input port change register (IPCR)
cause the input change bit in the interrupt status register (ISR [7]) to
be set. If a bit is in the ‘on’ state the setting of the corresponding bit
in the IPCR will also result in the setting of ISR[7], which results in
the generation of an interrupt output if IMR[7] = 1. If a bit is in the
‘off’ state, the setting of that bit in the IPCR has no effect on ISR[7].
ACR(6:4)
MODE
CLOCK SOURCE
000
Counter
External (I/02A)
001
Counter
TxC A – 1X clock of Channel A
transmitter
010
Counter
TxC B – 1X clock of Channel B
transmitter
011
Counter
(X1/Sclk) clock divided by 16
100
Timer
External (I/O 2A)
101
Timer
External (I/O2 A) divided by 16
110
Timer
Crystal or external clock (X1/Sclk)
111
Timer
(X1/Sclk) clock divided by 16
NOTE: The timer mode generates a square wave.
2005 Nov 01
46
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
ISR – Interrupt Status Register
This register provides the status of all potential interrupt sources. The contents of this register are masked by the Interrupt Mask Register (IMR).
If a bit in the ISR is a ‘1’ and the corresponding bit in the IMR is also a ‘1’ then INTRN output will be asserted (Low). If the corresponding bit in
the IMR is a zero the state of the bit in the ISR has no effect on the INTRN output. Note that the IMR does not mask the reading of the ISR – the
true status will be provided regardless of the contents of the IMR. The contents of this register are initialized to H‘00’ when the DUART is reset.
ISR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
INPUT
PORT
CHANGE
DELTA
Break B
RxRDY/
FFULL B
TxRDY B
Counter
Ready
Delta
Break A
RxRDY/
FFULL A
TxRDY A
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
0=not enabled
1=enabled
In the timer mode, this bit is set once each cycle of the generated
square wave (every other time that the counter/timer reaches zero
count). The bit is reset by a stop counter command. The command,
however, does not stop the counter/timer.
ISR[7] – Input Port Change Status
This bit is a ‘1’ when a change–of–state has occurred at the
I/O(3:0)A or B inputs and that event has been selected to cause an
interrupt by the programming of ACR[3:0]. The bit is cleared when
the CPU reads the IPCR.
ISR[2] – Channel A Change in Break
This bit, when set, indicates that the Channel A receiver has
detected the beginning or the end of a received break. It is reset
when the CPU issues a Channel A ‘reset break change interrupt’
command.
ISR[6] – Channel B Change In Break
This bit, when set, indicates that the Channel B receiver has
detected the beginning or the end of a received break. It is reset
when the CPU issues a Channel B ‘reset break change interrupt’
command.
ISR[1] – Rx A Interrupt
This bit indicates that the channel A receiver is interrupting
according to the fill level programmed by the MR0 and MR1
registers. This bit has a different meaning than the receiver
ready/full bit in the status register.
ISR[5] – Rx B Interrupt
This bit indicates that the channel B receiver is interrupting
according to the fill level programmed by the MR0 and MR1
registers. This bit has a different meaning than the receiver
ready/full bit in the status register.
ISR[0] – Tx A Interrupt
This bit indicates that the channel A transmitter is interrupting
according to the interrupt level programmed in the MR0[5:4] bits.
This bit has a different meaning than the Tx RDY bit in the status
register.
ISR[4] – Tx B Interrupt
This bit indicates that the channel B transmitter is interrupting
according to the interrupt level programmed in the MR0[5:4] bits.
This bit has a different meaning than the Tx RDY bit in the status
register.
ISR[3] – Counter Ready.
In the counter mode, this bit is set when the counter reaches
terminal count and is reset when the counter is stopped by a stop
counter command.
2005 Nov 01
47
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
IMR – Interrupt Mask Register
The programming of this register selects which bits in the ISR causes an interrupt output. If a bit in the ISR is a ‘1’ and the corresponding bit in
the IMR is also a ‘1’ the INTRN output will be asserted. If the corresponding bit in the IMR is a zero, the state of the bit in the ISR has no effect
on the INTRN output. Note that the IMR does not mask the programmable interrupt outputs I/O3 B–I/O7 B or the reading of the ISR.
IMR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
INPUT PORT
CHANGE
Delta
Break B
RxRDY/
FFULL B
TxRDY B
Counter
Ready
Delta
Break A
RxRDY/
FFULL A
TxRDY A
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
0=not
enabled
1=enabled
CTPU Counter Timer Preset Upper (Counter/Timer 0)
CPTU
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
BIT 3
BIT 2
BIT 1
BIT 0
BIT 3
BIT 2
BIT 1
BIT 0
BIT 3
BIT 2
BIT 1
BIT 0
The upper eight (8) bits for the 16 bit counter timer preset register
CTPL Counter –Timer Preset Lower (Counter/Timer 0)
CTPL
Bit 7
BIT 6
BIT 5
BIT 4
The lower eight (8) bits for the 16 bit counter timer preset register
CTVU Counter Timer Value Upper (Counter/Timer 0)
CPVL
Bit 7
BIT 6
BIT 5
BIT 4
The lower eight (8) bits for the 16 bit counter timer value
CTVL Counter –Timer Value Lower (Counter/Timer 0)
CTVL
Bit 7
BIT 6
BIT 5
BIT 4
The lower eight (8) bits for the 16 bit counter timer value register
Only the counter/timer 0 is available in the low order 16–position address map. Issuing the start command loads the C/T with the preset value.
The Stop command resets the C/T ready bit in the ISR (Interrupt status Register) and captures the C/T value in the output latches of the C/T. In
the special time out mode the start and stop commands are ignored. The ‘start command is executed by a read at address 0xE; the stop at 0xF.
IVR Interrupt Vector register in 68K mode and General purpose read write register in the x86 mode
IVR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
The eight (8) bits of the interrupt vector in the 68K mode.
IPR Input Port Register I/O(6:0) A
IPR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
Logical levels or the I/O[6:0] A, Bit 7 read as ‘1’
2005 Nov 01
48
BIT 2
BIT 1
BIT 0
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
OPCR Output Port Configuration Register. Controls [7:2] B
Bit 7
BIT 6
BIT 5
BIT 4
BIT (3:2)
BIT (1:0)
I/O7 B
I/O6 B
I/O5 B
I/O4 B
I/O3 B
I/O2 B
0 = OPR[7]
1 = Tx RDY B
0 = OPR[6]
1 = Tx RDY A
0 = OPR[5]
1 = Rx RDY / FFULL B
0 = OPR[4]
1 = Rx RDY / FFULL A
00 = OPR[3]
01 = C/T OUTPUT
10 = TxC B(1X)
11 = RxC B(1X)
00 = OPR[2]
01 = TxC A(16X)
10 = TxC A(1X)
11 = RxC A(1X)
NOTE: I/O0 B and I/O1 B output OPR(0) and OPR(1) respectively.
Under program control of MR1 and MR2 the signals RTSN A for
I/O0 B and RTSN B for I/O1 B may be assigned.
open–drain output. Note that this output is not masked by the
contents of the IMR.
OPCR[3:2] – This bit programs the I/O3 B output to provide one of
the following:
OPCR[7] – This bit programs the I/O7 B output to provide one of the
following:
• 00 The complement of OPR[3].
• 01 The counter/timer output, in which case I/O3 acts as an
• 0 The complement of OPR[7].
• 1 The Channel B transmitter interrupt output which is the
open–drain output. In the timer mode, this output is a square wave
at the programmed frequency. In the counter mode, the output
remains high until terminal count is reached, at which time it goes
low. The output returns to the high state when the counter is
stopped by a stop counter command. Note that this output is not
masked by the contents of the IMR.
complement of ISR[4]. When in this mode I/O7 acts as an open–
drain output. Note that this output is not masked by the contents
of the IMR.
OPCR[6] – This bit programs the I/O6 B output to provide one of the
following:
• 10 The 1X clock for the Channel B transmitter that shifts the
• 0 The complement of OPR[6].
• 1 The Channel A transmitter interrupt output which is the
transmitted data. If data is not being transmitted, a free running 1X
clock is output.
• 11 The 1X clock for the Channel B receiver that samples the
complement of ISR[0]. When in this mode I/O6 acts as an open–
drain output. Note that this output is not masked by the contents
of the IMR.
received data. If data is not being received, a free running 1X
clock is output.
OPCR[5] – This bit programs the I/O5 B output to provide one of the
following:
OPCR[1:0] – This field programs the I/O2 B output to provide one of
the following:
• 0 The complement of OPR[5].
• 1 The Channel B receiver interrupt output which is the
• 00 The complement of OPR[2].
• 01 The 16X clock for the Channel A transmitter. This is the clock
complement of ISR[5]. When in this mode I/O5 acts as an
open–drain output. Note that this output is not masked by the
contents of the IMR.
selected by CSR A [3:0], and will be a 1X clock if CSR A [3:0] =
1111.
• 10 The 1X clock for the Channel A transmitter that shifts the
OPCR[4] – This field programs the I/O4 B output to provide one of
the following:
transmitted data. If data is not being transmitted, a free running 1X
clock is output.
• 0 The complement of OPR[4].
• 1 The Channel A receiver interrupt output which is the
• 11 The 1X clock for the Channel A receiver that samples the
received data. If data is not being received, a free running 1X
clock is output.
complement of ISR[1]. When in this mode I/O4 acts as an
2005 Nov 01
49
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
SOPR – Set Bits in the OPR
Ones in the byte written to this register will cause the corresponding bit positions in the OPR to set to 1. Zeros have no effect. This allows
software to set individual bits without keeping a copy of the OPR bit configuration.
Set OPR
Bits
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
I/O7 B
I/O6 B
I/O5 B
I/O4 B
I/O3 B
I/O2 B
I/O1 B
I/O0 B
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
1=set bit
0=no change
ROPR – Reset Bits in the OPR
Ones in the byte written to the ROPR will cause the corresponding bit positions in the OPR to set to 0. Zeros have no effect. This allows
software to reset individual bits with our keeping a copy of the OPR bit configuration.
Reset OPR
Bits
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
I/O7 B
I/O6 B
I/O5 B
I/O4 B
I/O3 B
I/O2 B
I/O1 B
I/O0 B
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
1=reset bit
0=no change
OPR Output Port Register
The bits in the OPR register are controlled by the use of the SOPR and ROPR commands. The output pins (OP pins) drive the compliment of
the data stored in this register.
OPR
2005 Nov 01
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
I/O7 B
I/O6 B
I/O5 B
I/O4 B
I/O3 B
I/O2 B
I/O1 B
I/O0 B
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
0=Pin High
1=Pin Low
50
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REGISTER MAPS
The registers of the SC28L202 are loosely partitioned into two
groups: those used in controlling data channels and those used in
handling the actual data flow and status. Below is shown the general
configuration of all the register addressed. The ‘Register Map
Summary’ shows the configuration of the lower four bits of the
address that is the same for the individual UARTs. It also shows
the addresses for the several in the address space of UART A and
UART B that apply to the total chip configuration. The ‘Register Map
Detail’ shows the use of every address in the 8–bit address space.
most part, differences in address between channel A and B differ by
0x08.
The first address from 0x00 to 0x0F refer to the legacy code for
previous Philips/Signetics two channel UARTs (DUARTs). This
feature is directed to the SC26C92. That part has 89-byte FIFOs,
but powers up to look like it has a 3-byte receiver FIFO and a 1-byte
transmitter FIFO. Other control registers structures of legacy parts
are compatible back to the SCN2681.
Registers that configure the whole chip are denoted by a ‘•’
symbol.
Any programming using the SC28L202 as it is intended would
always use the address space form 0x10 through 0x7F. For the
REGISTER MAP DETAIL (based on 28L92)
NOTE: Addresses 0x00 to 0x0F represent the ‘C92 Register’ map.
A[6:0]
READ
WRITE
DEFAULT. The first 16 read and write locations are legacy code for other ’92-type UARTs.
000 0000 (0x00)
Mode Register (MR0 A, MR1 A, MR2 A) DEFAULT
Mode Register (MR0 A, MR1 A, MR2 A) DEFAULT
000 0001 (0x01)
Status Register (SR A)
Clock Select Register (CSR A) DEFAULT
000 0010 (0x02)
Command Register (CR A) DEFAULT
000 0011 (0x03)
Receiver FIFO Register (RxFIFO A)
Transmitter FIFO Register (TxFIFO A)
000 0100 (0x04)
Input Port Change Register (IPCR) DEFAULT
• Auxiliary Control Register (ACR) DEFAULT
000 0101 (0x05)
• Interrupt Status Register (ISR) DEFAULT
• Interrupt Mask Register (IMR) DEFAULT
000 0110 (0x06)
Counter Timer Value Register Upper (CTVU 0)
Counter Timer Preset Register Upper (CTPU 0)
000 0111 (0x07)
Counter Timer Value Register Lower (CTVL 0)
Counter Timer Preset Register Lower (CTPL 0)
000 1000 (0x08)
Mode Register (MR0 B, MR1 B, MR2 B) DEFAULT
Mode Register (MR0 B, MR1 B, MR2 B) DEFAULT
000 1001 (0x09)
Status Register (SR B)
Clock Select Register (CSR B) DEFAULT
000 1010 (0x0A)
Command Register (CR B) DEFAULT
000 1011 (0x0B)
Receiver FIFO Register (RxFIFO B)
Transmitter FIFO Register (TxFIFO B)
000 1100 (0x0C)
• Interrupt Vector Register (IVR) GLOBAL
• Interrupt Vector Register (IVR) GLOBAL
000 1101 (0x0D)
Input Port Register (IPR) I/O(6:0) A
Output Port Configuration Register (OPCR) I/O(7:2)B
000 1110 (0x0E)
Start Counter Command DEFAULT C/T 0
Set Output Port Register (SOPR) I/O(7:0)B
000 1111 (0x0F)
Stop Counter Command DEFAULT C/T 0
Reset Output Port Register (ROPR) I/O(7:0)B
EXTENSION
001 0000 (0x10)
Receiver FIFO Fill Level (RxFL A)
Set Output Port Register (SOPR A)
001 0001 (0x11)
Transmitter FIFO Empty level (TxEL A)
Reset Output Port Register (ROPR A)
001 0010 (0x12)
• Enhanced Operation Status (EOS)
Command Register Extension (CRx A)
001 0011 (0x13)
Input Port Change Register Upper (IPCRU A)
I/O Port Configuration Register 0 (I/OPCR 0)
001 0100 (0x14)
Input Port Change Register Lower (IPCRL A)
I/O Port Configuration Register 1 (I/OPCR 1)
001 0101 (0x15)
Input Port Register (IPR A)
001 0110 (0x16)
Counter Timer Value Register Upper (CTVU 0)
Counter Timer Preset Register Upper (CTPU 0)
001 0111 (0x17)
Counter Timer Value Register Lower (CTVL 0)
Counter Timer Preset Register Lower (CTPL 0)
001 1000 (0x18)
Receiver FIFO Fill Level (RxFL B)
Set Output Port Register (SOPR B)
001 1001 (0x19)
Transmitter FIFO Empty level (TxEL B)
Reset Output Port Register (ROPR B)
001 1010 (0x1A)
Command Register Extension (CRx B)
001 1011 (0x1B)
Input Port Change Register Upper (IPCRU B)
I/O Port Configuration Register 2 (I/OPCR 2)
001 1100 (0x1C)
Input Port Change Register Lower (IPCRL B)
I/O Port Configuration Register 3 (I/OPCR 3)
001 1101 (0x1D)
Input Port Register (IPR B)
001 1110 (0x1E)
Counter Timer Value Register Upper (CTVU 1)
Counter Timer Preset Register Upper (CTPU 1)
001 1111 (0x1F)
Counter Timer Value Register Lower (CTVL 1)
Counter Timer Preset Register Lower (CTPL 1)
2005 Nov 01
51
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REGISTER MAP
NOTE: The register maps for channels A and B (UARTs A and B) contain some control registers that configure the entire chip.
These are denoted by a ‘•’ symbol
A[6:0]
READ
WRITE
EXTENSION
010 0000 (0x20)
Mode Register 0 (MR0 A) NEW ADDRESS
Mode Register 0 (MR0 A) NEW ADDRESS
010 0001 (0x21)
Mode Register 1 (MR1 A) NEW ADDRESS
Mode Register 1 (MR1 A) NEW ADDRESS
010 0010 (0x22)
Mode Register 2 (MR2 A) NEW ADDRESS
Mode Register 2 (MR2 A) NEW ADDRESS
010 0011 (0x23)
Mode Register 3 (MR3 A) NEW ADDRESS
Mode Register 3 (MR3 A) NEW ADDRESS
010 0100 (0x24)
Counter/Timer Clock Source (CTCS 0)
Counter/Timer Clock Source (CTCS 0)
010 0101 (0x25)
Interrupt Status Register (ISR A)
Interrupt Mask Register (IMR A)
010 0110 (0x26)
Programmable BRG Preset Lower (PBRGPL 0)
Programmable BRG Preset Lower (PBRGPL 0)
010 0111 (0x27)
Programmable BRG Preset Upper (PBRGPU 0)
Programmable BRG Preset Upper (PBRGPU 0)
010 1000 (0x28)
Mode Register 0 (MR0 B) NEW ADDRESS
Mode Register 0 (MR0 B) NEW ADDRESS
010 1001 (0x29)
Mode Register 1 (MR1 B) NEW ADDRESS
Mode Register 1 (MR1 B) NEW ADDRESS
010 1010 (0x2A)
Mode Register 2 (MR2 B) NEW ADDRESS
Mode Register 2 (MR2 B) NEW ADDRESS
010 1011 (0x2B)
Mode Register 3 (MR3 B) NEW ADDRESS
Mode Register 3 (MR3 B) NEW ADDRESS
010 1100 (0x2C)
Counter/Timer Clock Source (CTCS 1)
Counter/Timer Clock Source (CTCS 1)
010 1101 (0x2D)
Interrupt Status Register (ISR B)
• Interrupt Mask Register (IMR B)
011 0000 (0x30)
Receiver Clock Select Register (RxCSR A)
Receiver Clock Select Register (RxCSR A)
011 0001 (0x31)
Transmitter Clock Select Register (TxCSR A)
Transmitter Clock Select Register (TxCSR A)
011 0010 (0x32)
Input Port Change Interrupt Enable (IPCE A)
Input Port Change Interrupt Enable (IPCE A)
011 0011 (0x33)
Programmable BRG Clock Source (PBRGCS)
Programmable BRG Clock Source (PBRGCS)
011 0110 (0x36)
Programmable BRG Preset Lower (PBRGPL 1)
Programmable BRG Preset Lower (PBRGPL 1)
011 0111 (0x37)
Programmable BRG Preset Upper (PBRGPU 1)
Programmable BRG Preset Upper (PBRGPU 1)
011 1000 (0x38)
Receiver Clock Select Register (RxCSR B)
Receiver Clock Select Register (RxCSR B)
011 1001 (0x39)
Transmitter Clock Select Register (TxCSR B)
Transmitter Clock Select Register (TxCSR B)
011 1010 (0x3A)
Input Port Change Interrupt Enable (IPCE B)
Input Port Change Interrupt Enable (IPCE B)
010 1110 (0x2E)
010 1111 (0x2F)
011 0100 (0x34)
011 0101 (0x35)
011 1011 (0x3B)
011 1100 (0x3C)
011 1101 (0x3D)
011 1110 (0x3E)
011 1111 (0x3F)
2005 Nov 01
52
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REGISTER MAP
NOTE: The register maps for channels A and B (UARTs A and B) contain some control registers that configure the entire chip.
These are denoted by a ‘•’ symbol
A[6:0]
READ
WRITE
NEW
100 0000 (0x40)
System Enable Status (SES A)
Watchdog, Character and X Enable(WCXER A)
100 0001 (0x41)
Xon Character Register (XonCR A)
Xon Character Register (XonCR A)
100 0010 (0x42)
Xoff Character Register (XoffCR A)
Xoff Character Register (XoffCR A)
100 0011 (0x43)
Address Recognition Character (ARCR A)
Address Recognition Character (ARCR A)
100 0100 (0x44)
Xon/Xoff Interrupt Status Register (XISR A)
100 0101 (0x45)
Special Function Register (SFR A)
Special Function Register (SFR A)
100 0110 (0x46)
Receiver FIFO Interrupt Level (RxFIL A)
Receiver FIFO Interrupt Level (RxFIL A)
100 0111 (0x47)
Transmitter FIFO Interrupt Level (TxFIL A)
Transmitter FIFO Interrupt Level (TxFIL A)
100 1000 (0x48)
System Enable Status (SES B)
Watchdog, Character and X Enable (WCXER B)
100 1001 (0x49)
Xon Character Register (XonCR B)
Xon Character Register (XonCR B)
100 1010 (0x4A)
Xoff Character Register (XoffCR B)
Xoff Character Register (XoffCR B)
100 1011 (0x4B)
Address Recognition Character (ARCR B)
Address Recognition Character (ARCR B)
100 1100 (0x4C)
Xon/Xoff Interrupt Status Register (XISR B)
100 1101 (0x4D)
Special Function Register (SFR B)
Special Function Register (SFR B)
100 1110 (0x4E)
Receiver FIFO Interrupt Level (RxFIL B)
Receiver FIFO Interrupt Level (RxFIL B)
100 1111 (0x4F)
Transmitter FIFO Interrupt Level (TxFIL B)
Transmitter FIFO Interrupt Level (TxFIL B)
101 0000 (0x50)
Bidding Control Register – Break Change (BCRBRK A)
Bidding Control Register – Break Change (BCRBRK A)
101 0001 (0x51)
Bidding Control Register – Change of State (BCRCOS A)
Bidding Control Register – Change of State (BCRCOS A)
101 0010 (0x52)
Bidding Control Register – Counter/Timer (BCRCT A)
Bidding Control Register – Counter/Timer (BCRCT A)
101 0011 (0x53)
Bidding Control Register – Xon (BCRx A)
Bidding Control Register – Xon (BCRx A)
101 0100 (0x54)
Bidding Control Register – Address (BCRA A)
Bidding Control Register – Address (BCRA A)
101 0101 (0x55)
Bidding Control Register – Loop Back Error (BCRLBE A)
Bidding Control Register – Loop Back Error (BCRLBE A)
101 1000 (0x58)
Bidding Control Register – Break Change (BCRBRK B)
Bidding Control Register – Break Change (BCRBRK B)
101 1001 (0x59)
Bidding Control Register – Change of State (BCRCOS B)
Bidding Control Register – Change of State (BCRCOS B)
101 1010 (0x5A)
Bidding Control Register – Counter/Timer (BCRCT B)
Bidding Control Register – Counter/Timer (BCRCT B)
101 1011 (0x5B)
Bidding Control Register – Xon (BCRx B)
Bidding Control Register – Xon (BCRx B)
101 1100 (0x5C)
Bidding Control Register – Address (BCRA B)
Bidding Control Register – Address (BCRA B)
101 1101 (0x5D)
Bidding Control Register – Loop Back Error (BCRLBE B)
Bidding Control Register – Loop Back Error (BCRLBE B)
101 0110 (0x56)
101 0111 (0x57)
101 1110 (0x5E)
101 1111 (0x5F)
2005 Nov 01
53
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REGISTER MAP
NOTE: The register maps for channels A and B (UARTs A and B) contain some control registers that configure the entire chip.
These are denoted by a ‘•’ symbol
A[6:0]
READ
WRITE
GLOBAL
110 0000 (0x60)
• Interrupt Control Register (ICR)
• Interrupt Control Register (ICR)
110 0001 (0x61)
• Current Interrupt Register (CIR)
• Update Current Interrupt Register (UCIR)
• Interrupt Vector Register (IVR)
• Interrupt Vector Register (IVR)
110 0110 (0x66)
• Global Chip Configuration Register (GCCR)
• Global Chip Configuration Register (GCCR)
110 0111 (0x67)
• Test & Revision Register (TRR)
• Test & Revision Register (TRR)
110 0010 (0x62)
110 0011 (0x63)
110 0100 (0x64)
110 0101 (0x65)
110 1000 (0x68)
110 1001 (0x69)
110 1010 (0x6A)
110 1011 (0x6B)
110 1100 (0x6C)
110 1101 (0x6D)
110 1110 (0x6E)
110 1111 (0x6F)
111 0000 (0x70)
• Global Interrupt Channel Register (GICR)
111 0001 (0x71)
• Global Interrupt Byte Count Register (GIBCR)
111 0010 (0x72)
• Global Interrupt Type Register (GITR)
111 0011 (0x73)
• Global RxFIFO Register (GRxFIFO)
• Global TxFIFO Register (GTxFIFO)
• Scan Test Control Register (STCR)
• Scan Test Control Register (STCR)
111 0100 (0x74)
111 0101 (0x75)
111 0110 (0x76)
111 0111 (0x77)
111 1000 (0x78)
111 1001 (0x79)
111 1010 (0x7A)
111 1011 (0x7B)
111 1100 (0x7C)
111 1101 (0x7D)
111 1110 (0x7E)
111 1111 (0x7F)
2005 Nov 01
54
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
GENERAL TIMING CONSIDERATIONS FOR THE SC28L202
This part is designed to operate in both the Intel (80xxx) and Motorola (68000) environments. When the Motorola mode is used, the definition,
function, polarity and timing of some pins change. See Figure 3 on page 61.
ABSOLUTE MAXIMUM RATINGS1
SYMBOL
PARAMETER
RATING
UNIT
Tamb
Operating ambient temperature
Note 4
°C
Tstg
Storage temperature range
–65 to +150
°C
VCC
Voltage from VCC to GND3
–0.5 to +7.0
V
range2
GND3
VSS
Voltage from any pin to
–0.5 to VCC +0.5
V
PD
Maximum power dissipation (TSSOP56)
2.4
W
Rth(j-c)
Thermal resistance, junction to case (TSSOP56)
20
W/°C
Rth(j-a)
Thermal resistance, junction to ambient (TSSOP56)
83
W/°C
NOTES:
1. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or any other condition above those indicated in the operation section of this specification is not
implied.
2. For operating at elevated temperatures, the device must be derated based on + 150_C maximum junction temperature.
3. This product includes circuitry specifically designed for the protection of its internal devices from damaging effects of excessive static
charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying any voltages larger than the rated maxima.
4. Parameters are valid over specified temperature range.
DC ELECTRICAL CHARACTERISTICS1, 2, 3 (NOMINAL 5 V)
VCC = 5 V ± 10%; Tamb = – 40 °C to +85 °C, unless otherwise specified
SYMBOL
PARAMETER
TEST CONDITIONS
LIMITS
UNIT
Min
Typ
Max
–
–
0.8
V
2.4
–
–
V
0.8*VCC
–
–
V
VIL
Input low voltage
VIH
Input high voltage (except X1/SCLK)
VIH
Input high voltage (X1/SCLK)
VOL
Output low voltage
IOL = 4 mA
–
–
0.4
V
VOH
Output high voltage (except open drain outputs)4
IOH = –400 µA
VCC – 0.5
–
–
V
IIX1PD
X1/SCLK input current – power-down
VIN = 0 to VCC
–1
–
1
µA
IILX1
X1/SCLK input low current – operating
VIN = 0 V
–30
–
0
µA
IIHX1
X1/SCLK input high current – operating
VIN = VCC
0
–
30
µA
Ii
Input leakage current
Input port and IACKN pins5
All other pins5
VIN = 0 to VCC
VIN = 0 to VCC
–10
–1
–
–
1
1
µA
µA
IOZH
Output off current high, 3–State data bus
VIN = VCC
–
–
5
µA
IOZL
Output off current low, 3–State data bus
VIN = 0 V
–5
–
–
µA
IODL
Open–drain output low current in off–state
VIN = 0 V
–10
–
–
µA
IODH
Open–drain output high current in off–state
VIN = VCC
–
–
1
µA
ICC
Power supply current6
Operating mode
Power-down mode
CMOS input levels; freq. = 10 MHz
CMOS input levels; freq. = 0 MHz
–
–
9
200
20
500
mA
µA
–40 °C to +85 °C
NOTES:
1. Parameters are valid over specified temperature range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/SCLK this swing is between 0.4 V and 4.4 V. All time measurements are referenced at input voltages of 0.8 V and
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Typical values are at +25 °C, typical supply voltages, and typical processing parameters.
4. Test conditions for outputs: CL = 85 pF, except interrupt outputs. Test conditions for interrupt outputs: CL = 85 pF, RL = 2.7 kΩ to VCC.
5. I/O port and IACKN pins have active pull-up transistors that will source a typical 2 µA from VCC when they are at VSS. At VCC they
source 0.0 µA.
6. All outputs are disconnected. Inputs are switching between CMOS levels of VCC – 0.2 V and VSS + 0.2 V.
2005 Nov 01
55
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
AC CHARACTERISTICS1, 2, 3 (NOMINAL 5 V)
VCC = 5 V ± 10%; Tamb = – 40 °C to +85 °C unless otherwise specified.
LIMITS4
Symbol
Parameter
Min
Typ
Max
UNIT
100
–
–
ns
Reset timing (See Figures 4, 5)
tRES
Reset Pulse Width
Bus Timing5 (See Figure 6)
tAS
A6–A0 set-up time to RDN, WRN Low
10
–
–
ns
tAH
A6–A0 hold time from RDN, WRN low
10
–
–
ns
tCS
CEN set-up time from RDN. WRN LOW
0
–
–
ns
tCH
CEN hold time from RDN. WRN HIGH
0
–
–
ns
tRW
WRN, RDN pulse width (Low time)
30
–
–
ns
tDD
Data valid after RDN low (85 pf load)
–
–
30
ns
0
–
–
ns
–
–
15
ns
active6
tDA
RDN low to data bus
tDF
Data bus floating after RDN or CEN high
invalid7
tDI
RDN or CEN high to data bus
0
–
–
ns
tDS
Data bus set-up time before WRN or CEN high (write cycle)
15
–
–
ns
tDH
Data hold time after WRN high
0
–
–
ns
10
–
–
ns
tRWD
High time between read and/or write
cycles5,7
Port Timing5 (See Figure 10)
tPS
Port in set-up time before RDN low (Read IP ports cycle)
0
–
–
ns
tPH
Port in hold time after RDN high
0
–
–
ns
tPD
OP port valid after WRN or CEN high (OPR write cycle)
–
–
30
ns
–
–
–
–
–
–
–
–
–
–
–
–
30
30
30
30
30
30
ns
ns
ns
ns
ns
ns
Interrupt Timing (See Figure 11)
tIR
INTRN (or I/O[7:3]B when used as interrupts) negated from:
Read RxFIFO (RxRDY/FFULL interrupt)
Write TxFIFO (TxRDY interrupt)
Reset Command (delta break change interrupt)
Stop C/T command (Counter/timer interrupt
Read IPCR (delta input port change interrupt)
Write IMR (Clear of change interrupt mask bit(s))
Clock Timing (See Figures 12, 13, 14)
tCLK
X1/SCLK high or low time
8
–
–
ns
fCLK
X1/SCLK frequency (7.0 to 16.2 MHz with crystal)
1.0
–
50
MHz
tCTC
C/T Clk (IP2) high or low time (C/T external clock input)
10
–
–
ns
fCTC
C/T Clk (IP2) frequency8
0
–
20
MHz
tRX
RxC high or low time (16X)
8
–
–
ns
fRX
RxC Frequency (16X)
0
–
50
MHz
RxC Frequency (1x)8,9
0
–
3
MHz
tTX
TxC High or low time (16X)
8
–
–
ns
fTX
TxC frequency (16X)
–
–
50
MHz
TxC frequency (1X)8,9
0
–
3
MHz
Transmitter Timing (See Figures 13, 15)
tTXD
TxD output delay from TxC low (TxC input pin)
–
–
30
ns
tTCS
Output delay from TxC output pin low to TxD data output
–
–
30
ns
Receiver Timing (See Figures 14, 16)
tRXS
RxD data set-up time to RxC high
20
–
–
ns
tRXH
RxD data hold time from RxC high
20
–
–
ns
2005 Nov 01
56
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
LIMITS4
Symbol
Parameter
Min
Typ
Max
UNIT
5
–
–
ns
68000 or Motorola bus timing (See Figures 7, 8, 9)
tCS(mot)
RWN set-up time to CEN LOW
HIGH10
tDS(mot)
Data bus set-up time before X1
10
–
–
ns
tDH(mot)
Data hold time after CEN HIGH
0
–
–
ns
tAS(mot)
Address set-up time to CEN LOW
10
–
–
ns
tAH(mot)
Address hold time from CEN LOW
10
–
–
ns
tDD(mot)
Data valid after CEN LOW
–
–
35
ns
cycles5, 7
tRWD(mot)
HIGH time between read and/or write
10
–
–
ns
tDCR
DACKN LOW (read cycle) from X1 HIGH
–
–
35
ns
tDCW
DACKN LOW (write cycle) from X1 HIGH
–
–
25
ns
tDAT
DACKN high impedance from CEN or IACKN HIGH
–
–
15
ns
tCSC
CEN or IACKN set–up time to X1 HIGH for minimum DACKN cycle
10
–
–
ns
NOTES:
1. Parameters are valid over specified temperature range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/SCLK this swing is between 0.4 V and 4.4 V. All time measurements are referenced at input voltages of 0.8 V and
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Test conditions for outputs: CL = 85 pF, except interrupt outputs. Test conditions for interrupt outputs: CL = 85 pF, RL = 2.7 kΩ to VCC.
4. Typical values are at +25 °C, typical supply voltages, and typical processing parameters.
5. Timing is illustrated and referenced to the WRN and RDN inputs. Also, CEN may be the ‘strobing’ input. CEN and RDN (also CEN and
WRN) are ORed internally. The signal asserted last initiates the cycle and the signal negated first terminates the cycle.
6. Guaranteed by characterization of sample units.
7. If CEN is used as the ‘strobing’ input, the parameter defines the minimum High times between one CEN and the next. The RDN signal must
be negated for tRWD time to guarantee that any status register changes are valid.
8. Minimum frequencies are not tested but are guaranteed by design.
9. Clocks for 1X mode should be reasonably symmetrical.
10. Data is usually set up with respect to CEN going LOW—the leading edge of CEN. This mode strongly implies the use of DACKN. (Its use is
not strictly required.) DACKN is derived from the X1/SCLK input. It is seldom that the system clocks that ultimately drive the CEN, address
and RWN signals are synchronous to the X1/SCLK. If address, data, RWN are set up before CEN goes LOW and hold through DACKN, the
timing parameters above will be guaranteed.
2005 Nov 01
57
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
DC ELECTRICAL CHARACTERISTICS1, 2, 3 (NOMINAL 3.3 V)
VCC = 3.3 V ± 10%; Tamb = – 40 °C to +85 °C unless otherwise specified
SYMBOL
PARAMETER
TEST CONDITIONS
UNIT
LIMITS
Min
Typ
Max
VIL
Input low voltage
–
–
0.2*VCC
V
VIH
Input high voltage (X1/SCLK)
0.8*VCC
–
–
V
VIH
Input high voltage (X1/SCLK)
2.4
–
–
V
VOL
Output low voltage
IOL = 4 mA
–
–
0.4
V
VOH
Output high voltage (except OD outputs)4
IOH = –400 µA
VCC–0.5
–
–
V
IIX1PD
X1/SCLK input current – power down
VIN = 0 V to VCC
–1
–
1
µA
IILX1
X1/SCLK input low current – operating
VIN = 0 V
–30
–
0
µA
IIHX1
X1/SCLK input high current – operating
VIN = VCC
0
–
30
µA
Ii
Input leakage current
I/O port pins and IACKN
All other pins5
VIN = 0 V to VCC
VIN = 0 V to VCC
–10
–1
–
–
1
1
µA
µA
IOZH
Output off current high, 3–State data bus
VIN = VCC
0
–
5
µA
IOZL
Output off current low, 3–State data bus
VIN = 0 V
–5
–
–
µA
IODL
Open–drain output low current in off–state
VIN = 0 V
–10
–
–
µA
IODH
Open–drain output high current in off–state
VIN = VCC
–
–
1
µA
CMOS input levels; freq. = 10 MHz
CMOS input levels; freq. = 0 MHz
–
–
9
200
20
500
mA
µA
ICC
current6
Power supply
Operating mode
Power down mode
NOTES:
1. Parameters are valid over specified temperature range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/SCLK this swing is between 0.4 V and 4.4 V. All time measurements are referenced at input voltages of 0.8 V and
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Typical values are at +25 °C, typical supply voltages, and typical processing parameters.
4. Test conditions for outputs: CL = 85 pF, except interrupt outputs. Test conditions for interrupt outputs: CL = 85 pF, RL = 2.7 kΩ to VCC.
5. I/O port pins have active pull-up transistors that will source a typical 2 µA from VCC when they are at VSS. These pins at VCC source 0.0 µA.
6. All outputs are disconnected. Inputs are switching between CMOS levels of VCC – 0.2 V and VSS + 0.2 V.
2005 Nov 01
58
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
AC CHARACTERISTICS1, 2, 3 (NOMINAL 3.3 V)
VCC = 3.3 V ± 10%; Tamb = – 40 °C to +85 °C unless otherwise specified
LIMITS4
Symbol
Parameter
Min
Typ
Max
UNIT
100
–
–
ns
Reset timing (See Figures 4, 5)
tRES
Reset Pulse Width
Bus Timing (See Figure 6)
tAS
A6–A0 set-up time to RDN, WRN Low
10
–
–
ns
tAH
A6–A0 hold time from RDN, WRN low
10
–
–
ns
tCS
CEN set-up time to RDN, WRN LOW
0
–
–
ns
tCH
CEN Hold time from RDN, WRN HIGH
0
–
–
ns
tRW
WRN, RDN pulse width (Low time)
40
–
–
ns
tDD
Data valid after RDN low (125 pF load) See load table for smaller loads
–
–
40
ns
tDA
RDN low to data bus active
0
–
–
ns
tDF
Data bus floating after RDN or CEN high
–
–
15
ns
tDS
Data bus set-up time before WRN or CEN high (write cycle)
15
–
–
ns
tDH
Data hold time after WRN high
0
–
–
ns
tRWD
High time between read and/or write cycles
10
–
–
ns
Port Timing (See Figure 10)
tPS
Port in set-up time before RDN low (Read IP ports cycle)
0
–
–
ns
tPH
Port in hold time after RDN high
0
–
–
ns
tPD
OP port valid after WRN or CEN high (OPR write cycle)
–
–
40
ns
–
–
–
–
–
–
–
–
–
–
–
–
40
40
40
40
40
40
ns
ns
ns
ns
ns
ns
Interrupt Timing (See Figure 11)
tIR
INTRN (or I/O(7:3)B when used as interrupts) negated from:
Read RxFIFO (RxRDY/FFULL interrupt)
Write TxFIFO (TxRDY interrupt)
Reset Command (delta break change interrupt)
Stop C/T command (Counter/timer interrupt
Read IPCR (delta input port change interrupt)
Write IMR (Clear of change interrupt mask bit(s))
Clock Timing (See Figures 12, 13, 14)
tCLK
X1/SCLK high or low time
10
–
–
ns
fCLK
X1/SCLK frequency (7.0 to 16.2 MHz with crystal)
1
–
34
MHz
tCTC
C/T Clk (IP2) high or low time (C/T external clock input)
10
–
–
ns
fCTC
C/T Clk (IP2) frequency
0
–
8
MHz
tRX
RxC high or low time (16X)
10
–
–
ns
fRX
RxC Frequency (16X)
0
–
24
MHz
RxC Frequency (1x)
0
–
1.5
MHz
tTX
TxC High or low time (16X)
10
–
–
ns
fTX
TxC frequency (16X)
0
–
24
MHz
TxC frequency (1X)
0
–
1.5
MHz
Transmitter Timing (See Figures 13, 15)
tTXD
TxD output delay from TxC low (TxC input pin)
–
–
40
ns
tTCS
Output delay from TxC output pin low to TxD data output
–
–
40
ns
Receiver Timing (See Figures 14, 16)
tRXS
RxD data set-up time to RxC high
20
–
–
ns
tRXH
RxD data hold time from RxC high
20
–
–
ns
2005 Nov 01
59
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
LIMITS4
Symbol
Parameter
Min
Typ
Max
UNIT
68000 or Motorola bus timing (See Figures 7, 8, 9)
tCS(mot)
RWN set-up time to CEN LOW
5
–
–
ns
tDS(mot)
Data bus set-up time before X1 HIGH
10
–
–
ns
tDH(mot)
Data hold time after CEN HIGH
0
–
–
ns
tAS(mot)
Address set-up time to CEN LOW
10
–
–
ns
tAH(mot)
Address hold time from CEN LOW
10
–
–
ns
tDD(mot)
Data valid after CEN LOW
–
–
45
ns
5, 7
tRWD(mot)
HIGH time between read and/or write cycles
10
–
–
ns
tDCR
DACKN Low (read cycle) from X1 High
–
–
35
ns
TDCW
DACKN Low (write cycle) from X1 High
–
–
30
ns
tDAT
DACKN High impedance from CEN or IACKN high
–
–
15
ns
tCSC
CEN or IACKN set-up time to X1 high for minimum DACKN cycle
10
–
–
ns
NOTES:
1. Parameters are valid over specified temperature range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/SCLK this swing is between 0.4 V and 4.4 V. All time measurements are referenced at input voltages of 0.8 V and
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Test conditions for outputs: CL = 85 pF, except interrupt outputs. Test conditions for interrupt outputs: CL = 85 pF, RL = 2.7 kΩ to VCC.
4. Typical values are at +25 °C, typical supply voltages, and typical processing parameters.
5. Timing is illustrated and referenced to the WRN and RDN inputs. Also, CEN may be the ‘strobing’ input. CEN and RDN (also CEN and
WRN) are ORed internally. The signal asserted last initiates the cycle and the signal negated first terminates the cycle.
6. Guaranteed by characterization of sample units.
7. If CEN is used as the ‘strobing’ input, the parameter defines the minimum High times between one CEN and the next. The RDN signal must
be negated for tRWD time to guarantee that any status register changes are valid.
8. Minimum frequencies are not tested but are guaranteed by design.
9. Clocks for 1X mode should be reasonably symmetrical.
10. Data is usually set up with respect to CEN going LOW—the leading edge of CEN. This mode strongly implies the use of DACKN. (Its use is
not strictly required.) DACKN is derived from the X1/SCLK input. It is seldom that the system clocks that ultimately drive the CEN, address
and RWN signals are synchronous to the X1/SCLK. If address, data, RWN are set up before CEN goes LOW and hold through DACKN, the
timing parameters above will be guaranteed.
TIMING DIAGRAMS
For the 68K mode, the CEN is very much the clock or ‘strobing’
signal. The RDN and WRN signals have been combined into the
RWN signal. Therefore, the part is always prepared to do a write or
read—it only needs CEN to enable.
The active time of read or write cycle exists only when CEN is LOW
and RDN or CEN is also LOW.
Write = CEN and WRN LOW.
Read = CEN and RDN LOW.
In the 68K mode design, care should be given to system drift over
temperature, voltage, and age when RWN and CEN change very
close to each other. If RWN switches shortly before CEN (due to
system drift) it is possible to produce very short internal read or write
pulses which could change internal controls, FIFO address pointers,
for example.
For the 68K mode:
Write = CEN LOW and RWN LOW and DACKN HIGH.
Read = CEN LOW and RWN HIGH.
In general, it is convenient (but is not at all required) to think of the
Read/Write signal to be active and then let the CEN be the ‘strobing’
or clocking control. However, some users have wired CEN LOW and
allowed RDN or WRN to be the clocking or ‘strobing’ input. While
this is completely within the specified limits, it is not recommended
since it will greatly increase the part’s sensitivity to noise ‘glitches’
on the RDN and WRN signals.
2005 Nov 01
Figure 3 loosely shows the timing conditions that may exist of the
active area those signals will produce.
60
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Intel-type bus:
Active area
CEN
RDN, RWN
CEN
RDN, WRN
CEN
RDN, WRN
CEN
RDN, WRN
Motorola-type:
Active area
CEN
RWN (Write)
DACKN
not used
RWN (Read)
CEN
When DACK
controls
RWN
DACKN
NOTE: In the 68K mode, the write occurs on the rise of CEN or fall of DACKN, whichever occurs first.
SD00734
Figure 3. Active area in 68K mode.
If you have further questions, please direct them to the factory contact:
[email protected]
2005 Nov 01
61
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
RESETN
RESETN
tRES
tRES
SD00729
SD00109
Figure 4. Reset Timing (80XXX mode)
Figure 5. Reset Timing (68XXX mode)
A0–A3
tAS
tAH
CEN
tCS
tCH
tRW
tRWD
RDN
tDD
D0–D7
(READ)
FLOAT
tDF
NOT
VALID
VALID
FLOAT
tRWD
WDN
tDS
tDH
D0–D7
(WRITE)
VALID
SD00087
Figure 6. Bus Timing (80XXX mode)
2005 Nov 01
62
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
tCSC
X1/CLK
tAS
A1–A4
tCS
tCH
RWN
tRWD
tAH
CEN
tDF
tDD
NOT
VALID
D0–D7
DATA VALID
tDA
DACKN
tDCR
tDAT
NOTE: DACKN low requires two rising edges of X1 clock after CEN is low.
SD00730
Figure 7. Bus Timing (Read Cycle) (68XXX mode)
tCSC
X1/CLK
tAS
A1–A4
RWN
tCS
tCH
tRWD
tAH
CEN
D0–D7
tDH
tDS
DACKN
tDCW
tDAT
NOTE: DACKN low requires two rising edges of X1 clock after CEN is low.
SD00731
Figure 8. Bus Timing (Write Cycle) (68XXX mode)
2005 Nov 01
63
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
tCSC
X1/CLK
INTRN
IACKN
tDD
tDF
D0–D7
DACKN
tDCR
tDAT
NOTE: DACKN low requires two rising edges of X1 clock after IACKN is low.
SD00732
Figure 9. Interrupt Cycle Timing (68XXX mode)
RDN
tPS
tPH
IP0–IP6
(a) INPUT PINS
WRN
tPD
OP0–OP7
OLD DATA
NEW DATA
(b) OUTPUT PINS
SD00135
Figure 10. Port Timing
2005 Nov 01
64
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
VM
WRN
tIR
INTERRUPT 1
OUTPUT
VOL +0.2 V
VOL
VM
RDN
tIR
INTERRUPT 1
OUTPUT
VOL +0.2 V
VOL
NOTES:
1. INTRN or OP3-OP7 when used as interrupt outputs.
2. The test for open-drain outputs is intended to guarantee switching of the output transistor. Measurement of this response is referenced from the midpoint of the switching
signal, VM, to a point 0.2 V above VOL. This point represents noise margin that assures true switching has occurred. Beyond this level, the effects of external circuitry and
test environment are pronounced and can greatly affect the resultant measurement.
SD00735
Figure 11. Interrupt Timing (80xxx mode)
VCC
tCLK
tCTC
tRx
tTx
NOTE:
RESISTOR REQUIRED
FOR TTL INPUT.
X1/SCLK
CTCLK
RxC
TxC
tCLK
tCTC
tRx
tTx
470 Ω
CLK
X1/Sclk
*NOTE: X2 MUST BE LEFT OPEN.
X2*
SC28L202
3 pF
PARASITIC CAPACITANCE
X1
TO UART
CIRCUIT
2pF
C1
TYP.
160 kΩ
C2
4pF
X2
3 pF
PARASITIC CAPACITANCE
14.7456 MHz
C1 = C2 ∼ 24 pF FOR CL = 13.5 pF. For the oscillator feedback loop the capacitors C1 and C2 are in series.
C1 and C2 should be chosen according to the crystal manufacturer’s specification.
C1 and C2 values will include any parasitic capacitance of the wiring and X1 X2 pins.
Package capacitance approximately 4 pF.
SD00736
Figure 12. Clock Timing
2005 Nov 01
65
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
1 BIT TIME
(1 OR 16 CLOCKS)
TxC
(INPUT)
tTXD
TxD
tTCS
TxC
(1X OUTPUT)
SD00138
Figure 13. Transmitter External Clocks
RxC
(1X INPUT)
tRXS
tRXH
RxD
SD00139
Figure 14. Receiver External Clock
TxD
D1
D2
D3
BREAK
D4
D6
TRANSMITTER
ENABLED
TxRDY
(SR2)
WRN
D1
D8
D9
START
BREAK
D10
CTSN1
(IP0)
STOP
BREAK
D11 WILL
NOT BE
WRITTEN TO
THE TxFIFO
D12
RTSN2
(OP0)
OPR(0) = 1
OPR(0) = 1
NOTES:
1. Timing shown for MR2[4] = 1.
2. Timing shown for MR2[5] = 1.
SD00155
Figure 15. Transmitter Timing
2005 Nov 01
66
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
D1
RxD
D2
D8
D9
D10
D11
D12
D13
D12, D13 WILL BE LOST
DUE TO RECEIVER DISABLE.
RECEIVER
ENABLED
RxRDY
(SR0)
FFULL
(SR1)
RxRDY/
FFULL
(OP5)2
RDN
STATUS DATA
STATUS DATA STATUS DATA STATUS DATA
D11 WILL BE LOST
DUE TO OVERRUN
D1
OVERRUN
(SR4)
D2
D3
D10
RESET BY COMMAND
RTS1
(OP0)
OPR[0] = 1
NOTES:
1. Timing shown for MR1[7] = 1.
2. Shown for OPCR[4] = 1 and MR[6] = 0.
SD00156
Figure 16. Receiver Timing
MASTER STATION
BIT 9
ADD#1 1
TxD
BIT 9
BIT 9
D0
ADD#2 1
0
TRANSMITTER
ENABLED
TxRDY
(SR2)
WRN
MR1[4:3] = 11
MR1[2] = 1
ADD#1 MR1[2] = 0 D0
PERIPHERAL STATION
BIT 9
0
RxD
MR1[2] = 1 ADD#2
BIT 9
ADD#1 1
BIT 9
BIT 9
D0
BIT 9
ADD#2 1
0
0
RECEIVER
ENABLED
RxRDY
(SR0)
RDN/WRN
MR1[4:3] = 11
ADD#1
STATUS DATA
STATUS DATA
D0
ADD#2
SD00096
Figure 17. Wake-Up Mode
2005 Nov 01
67
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
I = 2.4 mA
INTRN
DACKN
+5 V
85 pF
I = 2.4 mA VOL return to VCC for a 0 level
I = 400 µA VOH return to VSS for a 1 level
D0–D7
TxDA/B
OP0–OP7
85 pF
SD00733
Figure 18. Test Conditions on Outputs
2005 Nov 01
68
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
TSSOP56: plastic thin shrink small outline package; 56 leads; body width 6.1 mm
2005 Nov 01
69
SOT364-1
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
REVISION HISTORY
Rev
Date
Description
_7
20051101
Product data sheet. Supersedes data of 16 April 2004 (9397 750 13049).
Modifications:
• Page 3, description for pin 21, I/M: changed “When HIGH or not connected configures the bus interface ...”
to “When HIGH configures the bus interface ...:”
• Page 6, section “Bus Interface”, second sentence: changed “If this pin is high or left open ...” to
“If this pin is HIGH ...”
• Page 34, UCIR — Update CIR; first sentence: changed “... address 0x8C.” to “... address 0x61.”
_6
20040416
Product data (9397 750 13049). Supersedes fifth version SC28L202_5 of 2002 Dec 03 (9397 750 10585).
_5
20031202
Product data (9397 750 10585). Supersedes fourth version SC28L202_4 of 2000 Feb 10 (9397 750 06826).
_4
20000210
Objective data (9397 750 06826).
2005 Nov 01
70
Philips Semiconductors
Product data sheet
Dual UART
SC28L202
Data sheet status
Level
Data sheet status [1]
Product
status [2] [3]
Definitions
I
Objective data
Development
This data sheet contains data from the objective specification for product development.
Philips Semiconductors reserves the right to change the specification in any manner without notice.
II
Preliminary data
Qualification
This data sheet contains data from the preliminary specification. Supplementary data will be published
at a later date. Philips Semiconductors reserves the right to change the specification without notice, in
order to improve the design and supply the best possible product.
III
Product data
Production
This data sheet contains data from the product specification. Philips Semiconductors reserves the
right to make changes at any time in order to improve the design, manufacturing and supply. Relevant
changes will be communicated via a Customer Product/Process Change Notification (CPCN).
[1] Please consult the most recently issued data sheet before initiating or completing a design.
[2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at URL
http://www.semiconductors.philips.com.
[3] For data sheets describing multiple type numbers, the highest-level product status determines the data sheet status.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For detailed information see
the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 60134). Stress above one or more of the limiting
values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given
in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no
representation or warranty that such applications will be suitable for the specified use without further testing or modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices, or systems where malfunction of these products can reasonably be
expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree
to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes — Philips Semiconductors reserves the right to make changes in the products—including circuits, standard cells, and/or software—described
or contained herein in order to improve design and/or performance. When the product is in full production (status ‘Production’), relevant changes will be communicated
via a Customer Product/Process Change Notification (CPCN). Philips Semiconductors assumes no responsibility or liability for the use of any of these products, conveys
no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent,
copyright, or mask work right infringement, unless otherwise specified.
 Koninklijke Philips Electronics N.V. 2005
All rights reserved. Printed in U.S.A.
Contact information
For additional information please visit
http://www.semiconductors.philips.com.
Fax: +31 40 27 24825
Date of release: 11-05
For sales offices addresses send e-mail to:
[email protected]
Document order number:
2005 Nov 01
71
SC28L202_7
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