P89LPC938 User manual

UM10119
P89LPC938 User manual
Rev. 03 — 7 June 2005
Document information
Info
Content
Keywords
P89LPC938
Abstract
Technical information for the P89LPC938 device.
User manual
UM10119
Philips Semiconductors
P89LPC938 User manual
Revision history
Rev
Date
3
20050607
Description
•
Corrected typographical error in Table 50 “Capture compare control register (CCRx address Exh) bit description”. Corrected Table 107 “Data EEPROM control register
(DEECON address F1h) bit allocation” and Table 108 “Data EEPROM control register
(DEECON address F1h) bit description”.
•
Revised Table 52 “Output compare pin behavior.” for OCMx1:0 =10.
2
20050304
Updated to 18 MHz spec
1
20050111
Initial version
Contact information
For additional information, please visit: http://www.semiconductors.philips.com
For sales office addresses, please send an email to: [email protected]
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1. Introduction
The P89LPC938 is a single-chip microcontroller designed for applications demanding
high-integration, low cost solutions over a wide range of performance requirements. The
P89LPC938 is based on a high performance processor architecture that executes
instructions in two to four clocks, six times the rate of standard 80C51 devices. Many
system-level functions have been incorporated into the P89LPC938 in order to reduce
component count, board space, and system cost.
1.1 Pin configuration
P2.0/ICB/AD07
1
28 P2.7/ICA
P2.1/OCD/AD06
2
27 P2.6/OCA
P0.0/CMP2/KBI0/AD05
3
26 P0.1/CIN2B/KBI1/AD00
P1.7/OCC/AD04
4
25 P0.2/CIN2A/KBI2/AD01
P1.6/OCB
5
24 P0.3/CIN1B/KBI3/AD02
P1.5/RST
6
23 P0.4/CIN1A/KBI4/AD03
VSS
7
P3.1/XTAL1
8
P3.0/XTAL2/CLKOUT
9
P89LPC938FDH
22 P0.5/CMPREF/KBI5
21 VDD
20 P0.6/CMP1/KBI6
P1.4/INT1 10
19 P0.7/T1/KBI7
P1.3/INT0/SDA 11
18 P1.0/TXD
P1.2/T0/SCL 12
17 P1.1/RXD
P2.2/MOSI 13
16 P2.5/SPICLK
P2.3/MISO 14
15 P2.4/SS
002aab101
Fig 1. P89LPC938 TSSOP28 pin configuration.
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P2.0/ICB/AD07
1
26 P0.1/CIN2B/KBI1/AD00
P2.1/OCD/AD06
2
27 P2.6/OCA
P0.0/CMP2/KBI0/AD05
3
28 P2.7/ICA
P1.7/OCC/AD04
4
P89LPC938 User manual
P1.6/OCB
5
25 P0.2/CIN2A/KBI2/AD01
P1.5/RST
6
24 P0.3/CIN1B/KBI3/AD02
VSS
7
P3.1/XTAL1
8
P3.0/XTAL2/CLKOUT
9
23 P0.4/CIN1A/KBI4/AD03
22 P0.5/CMPREF/KBI5
P89LPC938FA
21 VDD
20 P0.6/CMP1/KBI6
P1.4/INT1 10
19 P0.7/T1/KBI7
P2.5/SPICLK 16
P1.1/RXD 17
P1.0/TXD 18
24 P2.7/ICA
23 P2.6/OCA
22 P0.1/CIN2B/KBI1/AD00
P2.4/SS 15
P2.3/MISO 14
P2.2/MOSI 13
P1.2/T0/SCL 12
P1.3/INT0/SDA 11
002aab085
25 P2.0/ICB/AD07
26 P2.1/OCD/AD06
terminal 1
index area
27 P0.0/CMP2/KBI0/AD05
28 P1.7/OCC/AD04
Fig 2. P89LPC938 PLCC28 pin configuration.
P1.6/OCB
1
21 P0.2/CIN2A/KBI2/AD01
P1.5/RST
VSS
2
20 P0.3/CIN1B/KBI3/AD02
P3.1/XTAL1
4
19 P0.4/CIN1A/KBI4/AD03
3
P89LPC938FHN
18
P0.5/CMPREF/KBI5
P1.0/TXD 14
P1.1/RXD 13
P2.5/SPICLK 12
15 P0.7/T1/KBI7
P2.4/SS 11
7
P2.3/MISO 10
P1.3/INT0/SDA
P2.2/MOSI
16 P0.6/CMP1/KBI6
9
6
8
5
P1.4/INT1
P1.2/T0/SCL
P3.0/XTAL2/CLKOUT
17 VDD
002aab073
Transparent top view
Fig 3. P89LPC938 HVQFN28 pin configuration.
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1.2 Pin description
Table 1:
Pin description
Symbol
Pin
Type Description
TSSOP28, HVQFN28
PLCC28
P0.0 to P0.7
I/O
Port 0: Port 0 is an 8-bit I/O port with a user-configurable output type.
During reset Port 0 latches are configured in the input only mode with the
internal pull-up disabled. The operation of Port 0 pins as inputs and
outputs depends upon the port configuration selected. Each port pin is
configured independently. Refer to Section 5.1 “Port configurations” on
page 34 for details.
The Keypad Interrupt feature operates with Port 0 pins.
All pins have Schmitt triggered inputs.
Port 0 also provides various special functions as described below:
P0.0/CMP2/
KBI0/AD05
P0.1/CIN2B/
KBI1/AD00
P0.2/CIN2A/
KBI2/AD01
P0.3/CIN1B/
KBI3/AD02
P0.4/CIN1A/
KBI4/AD03
3
26
25
24
23
P0.5/CMPREF/ 22
KBI5
27
22
21
20
19
18
I/O
P0.0 — Port 0 bit 0.
O
CMP2 — Comparator 2 output.
I
KBI0 — Keyboard input 0.
I
AD05 — ADC0 channel 5 analog input.
I/O
P0.1 — Port 0 bit 1.
I
CIN2B — Comparator 2 positive input B.
I
KBI1 — Keyboard input 1.
I
AD00 — ADC0 channel 0 analog input.
I/O
P0.2 — Port 0 bit 2.
I
CIN2A — Comparator 2 positive input A.
I
KBI2 — Keyboard input 2.
I
AD01 — ADC0 channel 1 analog input.
I/O
P0.3 — Port 0 bit 3.
I
CIN1B — Comparator 1 positive input B.
I
KBI3 — Keyboard input 3.
I
AD02 — ADC0 channel 2 analog input.
I/O
P0.4 — Port 0 bit 4.
I
CIN1A — Comparator 1 positive input A.
I
KBI4 — Keyboard input 4.
I
AD03 — ADC0 channel 3 analog input.
I/O
P0.5 — Port 0 bit 5.
I
CMPREF — Comparator reference (negative) input.
I
KBI5 — Keyboard input 5.
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Table 1:
Pin description …continued
Symbol
Pin
Type Description
TSSOP28, HVQFN28
PLCC28
P0.6/CMP1/
KBI6
P0.7/T1/KBI7
20
19
16
15
I/O
P0.6 — Port 0 bit 6.
O
CMP1 — Comparator 1 output.
I
KBI6 — Keyboard input 6.
I/O
P0.7 — Port 0 bit 7.
I/O
T1 — Timer/counter 1 external count input or overflow output.
I
KBI7 — Keyboard input 7.
I/O, I Port 1: Port 1 is an 8-bit I/O port with a user-configurable output type,
except for three pins as noted below. During reset Port 1 latches are
configured in the input only mode with the internal pull-up disabled. The
operation of the configurable Port 1 pins as inputs and outputs depends
upon the port configuration selected. Each of the configurable port pins
are programmed independently. Refer to Section 5.1 “Port configurations”
on page 34 for details. P1.2 to P1.3 are open drain when used as outputs.
P1.5 is input only.
P1.0 to P1.7
[1]
All pins have Schmitt triggered inputs.
Port 1 also provides various special functions as described below:
P1.0/TXD
P1.1/RXD
P1.2/T0/SCL
18
17
12
P1.3/INT0/ SDA 11
P1.4/INT1
P1.5/RST
P1.6/OCB
10
6
5
14
13
8
7
6
2
1
I/O
P1.0 — Port 1 bit 0.
O
TXD — Transmitter output for the serial port.
I/O
P1.1 — Port 1 bit 1.
I
RXD — Receiver input for the serial port.
I/O
P1.2 — Port 1 bit 2 (open-drain when used as output).
I/O
T0 — Timer/counter 0 external count input or overflow output (open-drain
when used as output).
I/O
SCL — I2C serial clock input/output.
I/O
P1.3 — Port 1 bit 3 (open-drain when used as output).
I
INT0 — External interrupt 0 input.
I/O
SDA — I2C serial data input/output.
I
P1.4 — Port 1 bit 4.
I
INT1 — External interrupt 1 input.
I
P1.5 — Port 1 bit 5 (input only).
I
RST — External Reset input during power-on or if selected via UCFG1.
When functioning as a reset input, a LOW on this pin resets the
microcontroller, causing I/O ports and peripherals to take on their default
states, and the processor begins execution at address 0. Also used
during a power-on sequence to force In-System Programming mode.
When using an oscillator frequency above 12 MHz, the reset input
function of P1.5 must be enabled. An external circuit is required to
hold the device in reset at power-up until VDD has reached its
specified level. When system power is removed VDD will fall below
the minimum specified operating voltage. When using an oscillator
frequency above 12 MHz, in some applications, an external
brownout detect circuit may be required to hold the device in reset
when VDD falls below the minimum specified operating voltage.
I/O
P1.6 — Port 1 bit 6.
O
OCB — Output Compare B.
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Table 1:
Pin description …continued
Symbol
Pin
Type Description
TSSOP28, HVQFN28
PLCC28
P1.7/OCC/
AD04
4
28
P2.0 to P2.7
I/O
P1.7 — Port 1 bit 7.
O
OCC — Output Compare C.
I
AD04 — ADC0 channel 4 analog input.
I/O
Port 2: Port 2 is an 8-bit I/O port with a user-configurable output type.
During reset Port 2 latches are configured in the input only mode with the
internal pull-up disabled. The operation of Port 2 pins as inputs and
outputs depends upon the port configuration selected. Each port pin is
configured independently. Refer to Section 5.1 “Port configurations” on
page 34 for details.
All pins have Schmitt triggered inputs.
Port 2 also provides various special functions as described below:
P2.0/ICB/ AD07 1
P2.1/OCD/
AD06
P2.2/MOSI
P2.3/MISO
P2.4/SS
P2.5/SPICLK
P2.6/OCA
P2.7/ICA
P3.0 to P3.1
2
13
14
15
16
27
28
25
26
9
10
11
12
23
24
I/O
P2.0 — Port 2 bit 0.
I
ICB — Input Capture B.
I
AD07 — ADC0 channel 7 analog input.
I/O
P2.1 — Port 2 bit 1.
O
OCD — Output Compare D.
I
AD06 — ADC0 channel 6 analog input.
I/O
P2.2 — Port 2 bit 2.
I/O
MOSI — SPI master out slave in. When configured as master, this pin is
output; when configured as slave, this pin is input.
I/O
P2.3 — Port 2 bit 3.
I/O
MISO — When configured as master, this pin is input, when configured
as slave, this pin is output.
I/O
P2.4 — Port 2 bit 4.
I
SS — SPI Slave select.
I/O
P2.5 — Port 2 bit 5.
I/O
SPICLK — SPI clock. When configured as master, this pin is output;
when configured as slave, this pin is input.
I/O
P2.6 — Port 2 bit 6.
O
OCA — Output Compare A.
I/O
P2.7 — Port 2 bit 7.
I
ICA — Input Capture A.
I/O
Port 3: Port 3 is a 2-bit I/O port with a user-configurable output type.
During reset Port 3 latches are configured in the input only mode with the
internal pull-up disabled. The operation of Port 3 pins as inputs and
outputs depends upon the port configuration selected. Each port pin is
configured independently. Refer to Section 5.1 “Port configurations” on
page 34 for details.
All pins have Schmitt triggered inputs.
Port 3 also provides various special functions as described below:
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User manual
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Table 1:
Pin description …continued
Symbol
Pin
Type Description
TSSOP28, HVQFN28
PLCC28
P3.0/XTAL2/
CLKOUT
P3.1/XTAL1
9
8
5
4
I/O
P3.0 — Port 3 bit 0.
O
XTAL2 — Output from the oscillator amplifier (when a crystal oscillator
option is selected via the Flash configuration.
O
CLKOUT — CPU clock divided by 2 when enabled via SFR bit (ENCLK
-TRIM.6). It can be used if the CPU clock is the internal RC oscillator,
watchdog oscillator or external clock input, except when XTAL1/XTAL2
are used to generate clock source for the RTC/system timer.
I/O
P3.1 — Port 3 bit 1.
I
XTAL1 — Input to the oscillator circuit and internal clock generator
circuits (when selected via the Flash configuration). It can be a port pin if
internal RC oscillator or watchdog oscillator is used as the CPU clock
source, and if XTAL1/XTAL2 are not used to generate the clock for the
RTC/system timer.
VSS
7
3
I
Ground: 0 V reference.
VDD
21
17
I
Power Supply: This is the power supply voltage for normal operation as
well as Idle and Power-Down modes.
[1]
Input/Output for P1.0 to P1.4, P1.6, P1.7. Input for P1.5.
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P89LPC938
ACCELERATED 2-CLOCK 80C51 CPU
8 kB
CODE FLASH
256-BYTE
DATA RAM
internal
bus
UART
TXD
RXD
I2C-BUS
SCL
SDA
SPICLK
MOSI
MISO
SS
SPI
512-BYTE
AUXILIARY RAM
REAL-TIME CLOCK/
SYSTEM TIMER
512-BYTE
DATA EEPROM
T0
T1
TIMER 0
TIMER 1
PORT 3
CONFIGURABLE I/Os
P3[1:0]
P2[7:0]
PORT 2
CONFIGURABLE I/Os
P1[7:0]
PORT 1
CONFIGURABLE I/Os
CMP2
ANALOG
COMPARATORS
CIN2A
CIN1A
OCA
CCU (CAPTURE/
COMPARE UNIT)
OCC
ICA
PORT 0
CONFIGURABLE I/Os
P0[7:0]
AD00
AD02
KEYPAD
INTERRUPT
ADC0
AD04
AD06
WATCHDOG TIMER
AND OSCILLATOR
PROGRAMMABLE
OSCILLATOR DIVIDER
CRYSTAL
OR
RESONATOR
X1
X2
CONFIGURABLE
OSCILLATOR
CIN2B
CMP1
CIN1B
OCB
OCD
ICB
AD01
AD03
AD05
AD07
CPU
clock
ON-CHIP
RC
OSCILLATOR
POWER MONITOR
(POWER-ON RESET,
BROWNOUT RESET)
002aab106
Fig 4. P89LPC938 block diagram.
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1.3 Special function registers
Remark: Special Function Registers (SFRs) accesses are restricted in the following ways:
• User must not attempt to access any SFR locations not defined.
• Accesses to any defined SFR locations must be strictly for the functions for the SFRs.
• SFR bits labeled ‘-’, ‘0’ or ‘1’ can only be written and read as follows:
– ‘-’ Unless otherwise specified, must be written with ‘0’, but can return any value
when read (even if it was written with ‘0’). It is a reserved bit and may be used in
future derivatives.
– ‘0’ must be written with ‘0’, and will return a ‘0’ when read.
– ‘1’ must be written with ‘1’, and will return a ‘1’ when read.
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Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers
* indicates SFRs that are bit addressable.
Name
Description
SFR Bit functions and addresses
addr.
MSB
Bit address
E7
E6
E5
Reset value
LSB
E4
E3
E2
E1
Hex
Binary
00
0000 0000
ADCS00 00
0000 0000
E0
E0H
AD0CON
ADC0 control register
97H
ENBI0
ENADCI
0
TMM0
EDGE0
ADCI0
ENADC0
ADCS01
AD0INS
ADC0 input select
A3H
ADI07
ADI06
ADI05
ADI04
ADI03
ADI02
ADI01
ADI00
00
0000 0000
AD0MOD
A
ADC0 mode register A
C0H
BNDI0
BURST0
SCC0
SCAN0
-
-
-
-
00
0000 0000
AD0MOD
B
ADC0 mode register B
A1H
CLK2
CLK1
CLK0
-
-
-
-
-
00
000x 0000
AUXR1
Auxiliary function register
A2H
CLKLP
EBRR
ENT1
ENT0
SRST
0
-
DPS
00
0000 00x0
F7
F6
F5
F4
F3
F2
F1
F0
B*
B register
F0H
00
0000 0000
BRGR0[2]
Baud rate generator rate
low
BEH
00
0000 0000
BRGR1[2]
Baud rate generator rate
high
BFH
00
0000 0000
BRGCON
Baud rate generator control
BDH
-
-
-
-
-
-
SBRGS
BRGEN
00[2]
xxxx xx00
CCCRA
Capture compare A control
register
EAH
ICECA2
ICECA1
ICECA0
ICESA
ICNFA
FCOA
OCMA1
OCMA0
00
0000 0000
CCCRB
Capture compare B control
register
EBH
ICECB2
ICECB1
ICECB0
ICESB
ICNFB
FCOB
OCMB1
OCMB0
00
0000 0000
CCCRC
Capture compare C control
register
ECH
-
-
-
-
-
FCOC
OCMC1
OCMC0
00
xxxx x000
CCCRD
Capture compare D control
register
EDH
-
-
-
-
-
FCOD
OCMD1
OCMD0
00
xxxx x000
CMP1
Comparator 1 control
register
ACH
-
-
CE1
CP1
CN1
OE1
CO1
CMF1
00[1]
xx00 0000
CMP2
Comparator 2 control
register
ADH
-
-
CE2
CP2
CN2
OE2
CO2
CMF2
00[1]
xx00 0000
DEECON
Data EEPROM control
register
F1H
EEIF
HVERR
ECTL1
ECTL0
-
-
-
EADR8
0E
0000 1110
Bit address
Rev. 03 — 7 June 2005
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ACC*
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Name
Description
SFR Bit functions and addresses
addr.
MSB
Reset value
LSB
Hex
Binary
DEEDAT
Data EEPROM data
register
F2H
00
0000 0000
DEEADR
Data EEPROM address
register
F3H
00
0000 0000
DIVM
CPU clock divide-by-M
control
95H
00
0000 0000
DPTR
Data pointer (2 bytes)
83H
00
0000 0000
DPH
DPL
Data pointer high
Rev. 03 — 7 June 2005
Data pointer low
82H
00
0000 0000
FMADRH
Program Flash address
high
E7H
00
0000 0000
FMADRL
Program Flash address low
E6H
00
0000 0000
FMCON
Program Flash control
(Read)
E4H
BUSY
-
-
-
HVA
HVE
SV
OI
70
0111 0000
Program Flash control
(Write)
E4H
FMCMD.
7
FMCMD.
6
FMCMD.
5
FMCMD.
4
FMCMD.
3
FMCMD.
2
FMCMD.
1
FMCMD.
0
I2ADR.6
I2ADR.5
I2ADR.4
I2ADR.3
I2ADR.2
I2ADR.1
I2ADR.0
GC
DF
DE
DD
DC
DB
DA
D9
D8
-
I2EN
STA
STO
SI
AA
-
CRSEL
FMDATA
Program Flash data
E5H
I2ADR
I2C slave address register
DBH
I2CON*
I2C
00
0000 0000
00
0000 0000
control register
I2DAT
I2C
00
x000 00x0
data register
I2SCLH
Serial clock generator/SCL
duty cycle register high
DDH
00
0000 0000
I2SCLL
Serial clock generator/SCL
duty cycle register low
DCH
00
0000 0000
I2STAT
I2C status register
D9H
F8
1111 1000
ICRAH
Input capture A register
high
ABH
00
0000 0000
ICRAL
Input capture A register low
AAH
00
0000 0000
ICRBH
Input capture B register
high
AFH
00
0000 0000
ICRBL
Input capture B register low
AEH
00
0000 0000
Bit address
D8H
Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers …continued
* indicates SFRs that are bit addressable.
DAH
STA.3
STA.2
STA.1
STA.0
0
0
0
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STA.4
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Name
Description
SFR Bit functions and addresses
addr.
MSB
Bit address
IEN0*
Interrupt enable 0
A8H
Bit address
IEN1*
IEN2
Interrupt enable 1
E8H
Interrupt enable 2
D5H
Bit address
IP0*
IP0H
Interrupt priority 0
B8H
Interrupt priority 0 high
B7H
Bit address
Rev. 03 — 7 June 2005
IP1*
IP1H
Interrupt priority 1
Interrupt priority 1 high
F8H
F7H
Reset value
LSB
Hex
Binary
00
0000 0000
AF
AE
AD
AC
AB
AA
A9
A8
EA
EWDRT
EBO
ES/ESR
ET1
EX1
ET0
EX0
EF
EE
ED
EC
EB
EA
E9
E8
EIEE
EST
-
ECCU
ESPI
EC
EKBI
EI2C
00[1]
00x0 0000
00[1]
00x0 0000
-
-
-
-
-
-
EADC
-
BF
BE
BD
BC
BB
BA
B9
B8
-
PWDRT
PBO
PS/PSR
PT1
PX1
PT0
PX0
00[1]
x000 0000
00[1]
x000 0000
-
PWDRT
H
PBOH
PSH/
PSRH
PT1H
PX1H
PT0H
PX0H
FF
FE
FD
FC
FB
FA
F9
F8
PADEE
PST
-
PCCU
PSPI
PC
PKBI
PI2C
00[1]
00x0 0000
PI2CH
00[1]
00x0 0000
00x0 0000
PADEEH
PSTH
-
PCCUH
PSPIH
PCH
PKBIH
IP2
Interrupt priority 2
D6H
-
-
-
-
-
-
PADC
-
00[1]
IP2H
Interrupt priority 2 high
D7H
-
-
-
-
-
-
PADCH
-
00[1]
00x0 0000
KBIF
00[1]
xxxx xx00
-
-
-
Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers …continued
* indicates SFRs that are bit addressable.
94H
-
-
-
PATN
_SEL
KBMASK
Keypad interrupt mask
register
86H
00
0000 0000
KBPATN
Keypad pattern register
93H
FF
1111 1111
OCRAH
Output compare A register
high
EFH
00
0000 0000
OCRAL
Output compare A register
low
EEH
00
0000 0000
OCRBH
Output compare B register
high
FBH
00
0000 0000
OCRBL
Output compare B register
low
FAH
00
0000 0000
OCRCH
Output compare C register
high
FDH
00
0000 0000
OCRCL
Output compare C register
low
FCH
00
0000 0000
UM10119
Keypad control register
P89LPC938 User manual
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KBCON
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Name
Description
SFR Bit functions and addresses
addr.
MSB
Reset value
LSB
Hex
Binary
OCRDH
Output compare D register
high
FFH
00
0000 0000
OCRDL
Output compare D register
low
FEH
00
0000 0000
P0*
Port 0
Bit address
80H
Bit address
P1*
Port 1
90H
Bit address
Rev. 03 — 7 June 2005
P2*
Port 2
P3*
Port 3
A0H
Bit address
P0M1
P0M2
B0H
Port 0 output mode 1
84H
Port 0 output mode 2
85H
87
86
85
84
83
82
81
80
T1/KB7
CMP1
/KB6
CMPREF
/KB5
CIN1A
/KB4
CIN1B
/KB3
CIN2A
/KB2
CIN2B
/KB1
CMP2
/KB0
97
96
95
94
93
92
91
90
OCC
OCB
RST
INT1
INT0/
SDA
T0/SCL
RXD
TXD
97
96
95
94
93
92
91
90
ICA
OCA
SPICLK
SS
MISO
MOSI
OCD
ICB
B7
B6
B5
B4
B3
B2
B1
B0
-
-
-
-
-
-
XTAL1
XTAL2
[1]
[1]
[1]
[1]
(P0M1.7) (P0M1.6) (P0M1.5) (P0M1.4) (P0M1.3) (P0M1.2) (P0M1.1) (P0M1.0)
FF[1]
1111 1111
(P0M2.7) (P0M2.6) (P0M2.5) (P0M2.4) (P0M2.3) (P0M2.2) (P0M2.1) (P0M2.0)
00[1]
0000 0000
D3[1]
11x1 xx11
P1M1
Port 1 output mode 1
91H
(P1M1.7) (P1M1.6)
-
(P1M1.4) (P1M1.3) (P1M1.2) (P1M1.1) (P1M1.0)
P1M2
Port 1 output mode 2
92H
(P1M2.7) (P1M2.6)
-
(P1M2.4) (P1M2.3) (P1M2.2) (P1M2.1) (P1M2.0) 00[1]
00x0 xx00
(P2M1.7) (P2M1.6) (P2M1.5) (P2M1.4) (P2M1.3) (P2M1.2) (P2M1.1) (P2M1.0)
FF[1]
1111 1111
(P2M2.7) (P2M2.6) (P2M2.5) (P2M2.4) (P2M2.3) (P2M2.2) (P2M2.1) (P2M2.0)
00[1]
0000 0000
03[1]
xxxx xx11
P2M1
P2M2
Port 2 output mode 1
A4H
Port 2 output mode 2
A5H
Port 3 output mode 1
B1H
-
-
-
-
-
-
(P3M1.1) (P3M1.0)
P3M2
Port 3 output mode 2
B2H
-
-
-
-
-
-
(P3M2.1) (P3M2.0) 00[1]
xxxx xx00
PCON
Power control register
87H
SMOD1
SMOD0
BOPD
BOI
GF1
GF0
PMOD1
VCPD
ADPD
D7
D6
D5
D4
CY
AC
F0
RS1
I2PD
0000 0000
00[1]
0000 0000
Power control register A
SPPD
SPD
CCUPD
PSW*
Program status word
D0H
D3
D2
D1
D0
RS0
OV
F1
P
00
0000 0000
PT0AD
Port 0 digital input disable
F6H
-
-
-
00
xx00 000x
RSTSRC
Reset source register
DFH
-
-
BOF
POF
R_BK
R_WD
R_SF
R_EX
RTCCON
RTC control
D1H
RTCF
RTCS1
RTCS0
-
-
-
ERTC
RTCEN
PT0AD.5 PT0AD.4 PT0AD.3 PT0AD.2 PT0AD.1
[3]
60[1][6]
011x xx00
UM10119
DEEPD
00
PCONA
Bit address
RTCPD
PMOD0
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P3M1
B5H
Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers …continued
* indicates SFRs that are bit addressable.
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Name
Description
SFR Bit functions and addresses
addr.
MSB
Reset value
LSB
Hex
Binary
0000 0000
RTCH
RTC register high
D2H
00[6]
RTCL
RTC register low
D3H
00[6]
0000 0000
SADDR
Serial port address register
A9H
00
0000 0000
SADEN
Serial port address enable
B9H
00
0000 0000
SBUF
Serial Port data buffer
register
99H
xx
xxxx xxxx
Bit address
9F
9E
9D
9C
9B
9A
99
98
Rev. 03 — 7 June 2005
Serial port control
98H
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
00
0000 0000
SSTAT
Serial port extended status
register
BAH
DBMOD
INTLO
CIDIS
DBISEL
FE
BR
OE
STINT
00
0000 0000
SP
Stack pointer
81H
07
0000 0111
SPCTL
SPI control register
E2H
SSIG
SPEN
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
04
0000 0100
SPSTAT
SPI status register
E1H
SPIF
WCOL
-
-
-
-
-
-
SPDAT
SPI data register
E3H
TAMOD
Timer 0 and 1 auxiliary
mode
8FH
8F
8E
8D
8C
8B
8A
89
88
TCON*
Timer 0 and 1 control
88H
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
TCR20*
CCU control register 0
C8H
PLEEN
HLTRN
HLTEN
ALTCD
ALTAB
TDIR2
TCR21
CCU control register 1
F9H
TCOU2
-
-
-
PLLDV.3
PLLDV.2
TH0
Timer 0 high
TH1
Timer 1 high
TH2
00
xxx0 xxx0
00
0000 0000
TMOD21 TMOD20 00
0000 0000
PLLDV.1
PLLDV.0 00
0xxx 0000
8CH
00
0000 0000
8DH
00
0000 0000
CCU timer high
CDH
00
0000 0000
TICR2
CCU interrupt control
register
C9H
TOIE2
TOCIE2D TOCIE2C TOCIE2B TOCIE2A
-
TICIE2B
TICIE2A 00
0000 0x00
TIFR2
CCU interrupt flag register
E9H
TOIF2
TOCF2D
TOCF2C
TOCF2B
TOCF2A
-
TICF2B
TICF2A
00
0000 0x00
TISE2
CCU interrupt status
encode register
DEH
-
-
-
-
-
ENCINT.
2
ENCINT.
1
ENCINT. 00
0
xxxx x000
TL0
Timer 0 low
8AH
00
0000 0000
TL1
Timer 1 low
8BH
00
0000 0000
-
-
T1M2
-
-
-
T0M2
UM10119
00xx xxxx
0000 0000
Bit address
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15 of 139
00
00
P89LPC938 User manual
SCON*
-
Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers …continued
* indicates SFRs that are bit addressable.
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Name
Description
SFR Bit functions and addresses
addr.
MSB
Reset value
LSB
Hex
Binary
00
0000 0000
T0M0
00
0000 0000
Rev. 03 — 7 June 2005
TL2
CCU timer low
CCH
TMOD
Timer 0 and 1 mode
89H
TOR2H
CCU reload register high
CFH
00
0000 0000
TOR2L
CCU reload register low
CEH
00
0000 0000
TPCR2H
Prescaler control register
high
CBH
TPCR2L
Prescaler control register
low
CAH
TRIM
Internal oscillator trim
register
96H
RCCLK
ENCLK
TRIM.5
TRIM.4
TRIM.3
TRIM.2
TRIM.1
TRIM.0
[5] [6]
WDCON
Watchdog control register
A7H
PRE2
PRE1
PRE0
-
-
WDRUN
WDTOF
WDCLK
[4] [6]
WDL
Watchdog load
C1H
WFEED1
Watchdog feed 1
C2H
WFEED2
Watchdog feed 2
C3H
[1]
T1GATE
-
T1C/T
-
T1M1
-
Philips Semiconductors
User manual
Table 2:
P89LPC938 Special function registers …continued
* indicates SFRs that are bit addressable.
T1M0
-
T0GATE
-
T0C/T
-
T0M1
TPCR2H. TPCR2H. 00
1
0
TPCR2L. TPCR2L. TPCR2L. TPCR2L. TPCR2L. TPCR2L. TPCR2L. TPCR2L. 00
7
6
5
4
3
2
1
0
FF
xxxx xx00
0000 0000
1111 1111
All ports are in input only (high-impedance) state after power-up.
[2]
BRGR1 and BRGR0 must only be written if BRGEN in BRGCON SFR is logic 0. If any are written while BRGEN = 1, the result is unpredictable.
[3]
The RSTSRC register reflects the cause of the UM10119 reset. Upon a power-up reset, all reset source flags are cleared except POF and BOF; the power-on reset value is
xx11 0000.
[4]
After reset, the value is 1110 01x1, i.e., PRE2 to PRE0 are all logic 1, WDRUN = 1 and WDCLK = 1. WDTOF bit is logic 1 after watchdog reset and is logic 0 after power-on reset.
Other resets will not affect WDTOF.
[5]
On power-on reset, the TRIM SFR is initialized with a factory preprogrammed value. Other resets will not cause initialization of the TRIM register.
[6]
The only reset source that affects these SFRs is power-on reset.
UM10119
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P89LPC938 extended special function registers [1]
Name
Description
Hex
Binary
ADC0HBND
ADC0 high _boundary register, left
(MSB)
FFEFh
SFR addr.
Bit functions and addresses
FF
1111 1111
ADC0LBND
ADC0 low_boundary register (MSB)
FFEEh
00
0000 0000
AD0DAT0R
ADC0 data register 0, right (LSB)
FFFEh
AD0DAT0[7:0]
00
0000 0000
AD0DAT0L
ADC0 data register 0, left (MSB)
FFFFh
AD0DAT0[9:2]
00
0000 0000
AD0DAT1R
ADC0 data register 1, right (LSB)
FFFCh
AD0DAT1[7:0]
00
0000 0000
AD0DAT1L
ADC0 data register 1, left (MSB)
FFFDh
AD0DAT1[9:2]
00
0000 0000
AD0DAT2R
ADC0 data register 2, right (LSB)
FFFAh
AD0DAT2[7:0]
00
0000 0000
AD0DAT2L
ADC0 data register 2, left (MSB)
FFFBh
AD0DAT2[9:2]
00
0000 0000
AD0DAT3R
ADC0 data register 3, right (LSB)
FFF8h
AD0DAT3[7:0]
00
0000 0000
AD0DAT3L
ADC0 data register 3, left (MSB)
FFF9h
AD0DAT3[9:2]
00
0000 0000
AD0DAT4R
ADC0 data register 4, right (LSB)
FFF6h
AD0DAT4[7:0]
00
0000 0000
AD0DAT4L
ADC0 data register 4, left (MSB)
FFF7h
AD0DAT4[9:2]
00
0000 0000
AD0DAT5R
ADC0 data register 5, right (LSB)
FFF4h
AD0DAT5[7:0]
00
0000 0000
AD0DAT5L
ADC0 data register 5, left (MSB)
FFF5h
AD0DAT5[9:2]
00
0000 0000
AD0DAT6R
ADC0 data register 6, right (LSB)
FFF2h
AD0DAT6[7:0]
00
0000 0000
AD0DAT6L
ADC0 data register 6, left (MSB)
FFF3h
AD0DAT6[9:2]
00
0000 0000
AD0DAT7R
ADC0 data register 7, right (LSB)
FFF0h
AD0DAT7[7:0]
00
0000 0000
AD0DAT7L
ADC0 data register 7, left (MSB)
FFF1h
AD0DAT7[9:2]
00
0000 0000
BNDSTA0
ADC0 boundary status register
FFEDh
BST07 BST06 BST05 BST04 BST03 BST02 BST01 BST00 00
0000 0000
MSB
Rev. 03 — 7 June 2005
[1]
Philips Semiconductors
User manual
Table 3:
Reset value
LSB
Extended SFRs are logically in external data memory space (XDATA) and are accessed using the MOVX A,@DPTR and MOVX @DPTR,A instructions.
UM10119
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UM10119
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P89LPC938 User manual
1.4 Memory organization
FF00h
FFEFh
1FFFh
Read-protected
IAP calls only
IAP entrypoints
IDATA routines
entry points for:
-51 ASM. code
-C code
ISP CODE
(512B)*
1E00h
1C00h
1BFFh
1800h
17FFh
1400h
13FFh
1000h
0FFFh
0C00h
0BFFh
0800h
07FFh
0400h
03FFh
SECTOR 7
SECTOR 4
FF1Fh
FF00h
entry
points
SPECIAL FUNCTION
REGISTERS
(DIRECTLY ADDRESSABLE)
IDATA (incl. DATA)
128 BYTES ON-CHIP
DATA MEMORY (STACK
AND INDIR. ADDR.)
DATA
ISP serial loader
entry points for:
-UART (auto-baud)
-I2C, SPI, etc.*
SECTOR 6
SECTOR 5
FFEFh
1FFFh
128 BYTES ON-CHIP
DATA MEMORY (STACK,
DIRECT AND INDIR. ADDR.)
4 REG. BANKS R[7:0]
1E00h
Flexible choices:
-as supplied (UART)
-Philips libraries*
-user-defined
data memory
(DATA, IDATA)
SECTOR 3
SECTOR 2
SECTOR 1
SECTOR 0
0000h
002aaa948
Fig 5. P89LPC938 memory map.
The various P89LPC938 memory spaces are as follows:
DATA — 128 bytes of internal data memory space (00h:7Fh) accessed via direct or
indirect addressing, using instruction other than MOVX and MOVC. All or part of the Stack
may be in this area.
IDATA — Indirect Data. 256 bytes of internal data memory space (00h:FFh) accessed via
indirect addressing using instructions other than MOVX and MOVC. All or part of the
Stack may be in this area. This area includes the DATA area and the 128 bytes
immediately above it.
SFR — Special Function Registers. Selected CPU registers and peripheral control and
status registers, accessible only via direct addressing.
CODE — 64 kB of Code memory space, accessed as part of program execution and via
the MOVC instruction. The P89LPC938 has 8 kB of on-chip Code memory.
Table 4:
Data RAM arrangement
Type
Data RAM
Size (bytes)
DATA
Directly and indirectly addressable memory
128
IDATA
Indirectly addressable memory
256
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User manual
Rev. 03 — 7 June 2005
18 of 139
UM10119
Philips Semiconductors
P89LPC938 User manual
2. Clocks
2.1 Enhanced CPU
The P89LPC938 uses an enhanced 80C51 CPU which runs at six times the speed of
standard 80C51 devices. A machine cycle consists of two CPU clock cycles, and most
instructions execute in one or two machine cycles.
2.2 Clock definitions
The P89LPC938 device has several internal clocks as defined below:
OSCCLK — Input to the DIVM clock divider. OSCCLK is selected from one of four clock
sources and can also be optionally divided to a slower frequency (see Figure 6 and
Section 2.8 “CPU Clock (CCLK) modification: DIVM register”). Note: fosc is defined as the
OSCCLK frequency.
CCLK — CPU clock; output of the DIVM clock divider. There are two CCLK cycles per
machine cycle, and most instructions are executed in one to two machine cycles (two or
four CCLK cycles).
RCCLK — The internal 7.373 MHz RC oscillator output.
PCLK — Clock for the various peripheral devices and is CCLK⁄2.
2.2.1 Oscillator Clock (OSCCLK)
The P89LPC938 provides several user-selectable oscillator options. This allows
optimization for a range of needs from high precision to lowest possible cost. These
options are configured when the FLASH is programmed and include an on-chip watchdog
oscillator, an on-chip RC oscillator, an oscillator using an external crystal, or an external
clock source. The crystal oscillator can be optimized for low, medium, or high frequency
crystals covering a range from 20 kHz to 18 MHz.
2.2.2 Low speed oscillator option
This option supports an external crystal in the range of 20 kHz to 100 kHz. Ceramic
resonators are also supported in this configuration.
2.2.3 Medium speed oscillator option
This option supports an external crystal in the range of 100 kHz to 4 MHz. Ceramic
resonators are also supported in this configuration.
2.2.4 High speed oscillator option
This option supports an external crystal in the range of 4 MHz to 18 MHz. Ceramic
resonators are also supported in this configuration. When using an oscillator frequency
above 12 MHz, the reset input function of P1.5 must be enabled. An external circuit
is required to hold the device in reset at power-up until VDD has reached its
specified level. When system power is removed VDD will fall below the minimum
specified operating voltage. When using an oscillator frequency above 12 MHz, in
some applications, an external brownout detect circuit may be required to hold the
device in reset when VDD falls below the minimum specified operating voltage.
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User manual
Rev. 03 — 7 June 2005
19 of 139
UM10119
Philips Semiconductors
P89LPC938 User manual
2.3 Clock output
The P89LPC938 supports a user-selectable clock output function on the XTAL2 /
CLKOUT pin when the crystal oscillator is not being used. This condition occurs if a
different clock source has been selected (on-chip RC oscillator, watchdog oscillator,
external clock input on X1) and if the Real-time Clock is not using the crystal oscillator as
its clock source. This allows external devices to synchronize to the P89LPC938. This
output is enabled by the ENCLK bit in the TRIM register
The frequency of this clock output is 1⁄2 that of the CCLK. If the clock output is not needed
in Idle mode, it may be turned off prior to entering Idle, saving additional power. Note: on
reset, the TRIM SFR is initialized with a factory preprogrammed value. Therefore when
setting or clearing the ENCLK bit, the user should retain the contents of other bits of the
TRIM register. This can be done by reading the contents of the TRIM register (into the
ACC for example), modifying bit 6, and writing this result back into the TRIM register.
Alternatively, the ‘ANL direct’ or ‘ORL direct’ instructions can be used to clear or set bit 6
of the TRIM register.
2.4 On-chip RC oscillator option
The P89LPC938 has a TRIM register that can be used to tune the frequency of the RC
oscillator. During reset, the TRIM value is initialized to a factory pre-programmed value to
adjust the oscillator frequency to 7.373 MHz ± 1 %. (Note: the initial value is better than
1 %; please refer to the P89LPC938 data sheet for behavior over temperature). End user
applications can write to the TRIM register to adjust the on-chip RC oscillator to other
frequencies. Increasing the TRIM value will decrease the oscillator frequency.
Table 5:
On-chip RC oscillator trim register (TRIM - address 96h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
RCCLK
ENCLK
TRIM.5
TRIM.4
TRIM.3
TRIM.2
TRIM.1
TRIM.0
Reset
0
0
Bits 5:0 loaded with factory stored value during reset.
Table 6:
On-chip RC oscillator trim register (TRIM - address 96h) bit description
Bit
Symbol
Description
0
TRIM.0
1
TRIM.1
2
TRIM.2
3
TRIM.3
Trim value. Determines the frequency of the internal RC oscillator. During reset,
these bits are loaded with a stored factory calibration value. When writing to either
bit 6 or bit 7 of this register, care should be taken to preserve the current TRIM value
by reading this register, modifying bits 6 or 7 as required, and writing the result to
this register.
4
TRIM.4
5
TRIM.5
6
ENCLK
when = 1, CCLK⁄2 is output on the XTAL2 pin provided the crystal oscillator is not
being used.
7
RCCLK
when = 1, selects the RC Oscillator output as the CPU clock (CCLK). This allows for
fast switching between any clock source and the internal RC oscillator without
needing to go through a reset cycle.
2.5 Watchdog oscillator option
The watchdog has a separate oscillator which has a frequency of 400 kHz. This oscillator
can be used to save power when a high clock frequency is not needed.
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User manual
Rev. 03 — 7 June 2005
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UM10119
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P89LPC938 User manual
2.6 External clock input option
In this configuration, the processor clock is derived from an external source driving the
XTAL1 / P3.1 pin. The rate may be from 0 Hz up to 18 MHz. The XTAL2 / P3.0 pin may be
used as a standard port pin or a clock output. When using an oscillator frequency
above 12 MHz, the reset input function of P1.5 must be enabled. An external circuit
is required to hold the device in reset at power-up until VDD has reached its
specified level. When system power is removed VDD will fall below the minimum
specified operating voltage. When using an oscillator frequency above 12 MHz, in
some applications, an external brownout detect circuit may be required to hold the
device in reset when VDD falls below the minimum specified operating voltage.
quartz crystal or
ceramic resonator
P89LPC932A1
XTAL1
(1)
XTAL2
002aab008
Note: The oscillator must be configured in one of the following modes: Low frequency crystal,
medium frequency crystal, or high frequency crystal.
(1) A series resistor may be required to limit crystal drive levels. This is especially important for low
frequency crystals (see text).
Fig 6. Using the crystal oscillator.
XTAL1
XTAL2
HIGH FREQUENCY
MEDIUM FREQUENCY
LOW FREQUENCY
RTC
OSCCLK
DIVM
CCLK
CPU
RCCLK
RC
OSCILLATOR
÷2
(7.3728 MHz ±1 %)
PCLK
WDT
WATCHDOG
OSCILLATOR
(400 kHz
+20%
)
−30 %
PCLK
TIMER 0 AND
TIMER 1
I2C-BUS
32 × PLL
SPI
UART
CCU
(P89LPC932A1)
002aaa891
Fig 7. Block diagram of oscillator control.
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2.7 Oscillator Clock (OSCCLK) wake-up delay
The P89LPC938 has an internal wake-up timer that delays the clock until it stabilizes
depending to the clock source used. If the clock source is any of the three crystal
selections, the delay is 992 OSCCLK cycles plus 60 µs to 100 µs. If the clock source is
either the internal RC oscillator or the Watchdog oscillator, the delay is 224 OSCCLK
cycles plus 60 µs to 100 µs.
2.8 CPU Clock (CCLK) modification: DIVM register
The OSCCLK frequency can be divided down, by an integer, up to 510 times by
configuring a dividing register, DIVM, to provide CCLK. This produces the CCLK
frequency using the following formula:
CCLK frequency = fosc / (2N)
Where: fosc is the frequency of OSCCLK, N is the value of DIVM.
Since N ranges from 0 to 255, the CCLK frequency can be in the range of fosc to fosc/510.
(for N = 0, CCLK = fosc).
This feature makes it possible to temporarily run the CPU at a lower rate, reducing power
consumption. By dividing the clock, the CPU can retain the ability to respond to events
other than those that can cause interrupts (i.e. events that allow exiting the Idle mode) by
executing its normal program at a lower rate. This can often result in lower power
consumption than in Idle mode. This can allow bypassing the oscillator start-up time in
cases where Power-down mode would otherwise be used. The value of DIVM may be
changed by the program at any time without interrupting code execution.
2.9 Low power select
The P89LPC938 is designed to run at 18 MHz (CCLK) maximum. However, if CCLK is
8 MHz or slower, the CLKLP SFR bit (AUXR1.7) can be set to a logic 1 to lower the power
consumption further. On any reset, CLKLP is logic 0 allowing highest performance. This
bit can then be set in software if CCLK is running at 8 MHz or slower.
3. A/D converter
3.1 General description
The P89LPC938 has a 10-bit, 8-channel multiplexed successive approximation
analog-to-digital converter module. A block diagram of the A/D converter is shown in
Figure 8. The A/D consists of an 8-input multiplexer which feeds a sample-and-hold circuit
providing an input signal to one of two comparator inputs. The control logic in combination
with the SAR drives a digital-to-analog converter which provides the other input to the
comparator. The output of the comparator is fed to the SAR.
3.2 A/D features
• 10-bit, 8-channel multiplexed input, successive approximation A/D converter.
• Eight result register pairs.
• Six operating modes
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– Fixed channel, single conversion mode
– Fixed channel, continuous conversion mode
– Auto scan, single conversion mode
– Auto scan, continuous conversion mode
– Dual channel, continuous conversion mode
– Single step mode
• Three conversion start modes
– Timer triggered start
– Start immediately
– Edge triggered
•
•
•
•
•
10-bit conversion time of 4 µs at an A/D clock of 9 MHz
Interrupt or polled operation
High and low boundary limits interrupt
Clock divider
Power down mode
comp
+
INPUT
MUX
SAR
–
CONTROL
LOGIC
8
DAC1
CCLK
002aab103
Fig 8. ADC block diagram.
3.2.1 A/D operating modes
3.2.1.1
Fixed channel, single conversion mode
A single input channel can be selected for conversion. A single conversion will be
performed and the result placed in the result register pair which corresponds to the
selected input channel (see Table 7). An interrupt, if enabled, will be generated after the
conversion completes. The input channel is selected in the ADINS register. This mode is
selected by setting the SCAN0 bit in the ADMODA register.
Table 7:
Input channels and result registers for fixed channel single, auto scan single, and
auto scan continuous conversion modes
Result register
Input channel
Result register
Input channel
AD0DAT0R/L
AD00
AD0DAT4R/L
AD04
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Table 7:
3.2.1.2
Input channels and result registers for fixed channel single, auto scan single, and
auto scan continuous conversion modes …continued
Result register
Input channel
Result register
Input channel
AD0DAT1R/L
AD01
AD0DAT5R/L
AD05
AD0DAT2R/L
AD02
AD0DAT6R/L
AD06
AD0DAT3R/L
AD03
AD0DAT7R/L
AD07
Fixed channel, continuous conversion mode
A single input channel can be selected for continuous conversion. The results of the
conversions will be sequentially placed in the eight result register pairs (see Table 8). The
user may select whether an interrupt can be generated after every four or every eight
conversions. Additional conversion results will again cycle through the result register
pairs, overwriting the previous results. Continuous conversions continue until terminated
by the user. This mode is selected by setting the SCC0 bit in the ADMODA register.
Table 8:
Result registers and conversion results for fixed channel, continuous conversion
mode
Result register
3.2.1.3
Contains
AD0DAT0R/L
Selected channel, first conversion result
AD0DAT1R/L
Selected channel, second conversion result
AD0DAT2R/L
Selected channel, third conversion result
AD0DAT3R/L
Selected channel, fourth conversion result
AD0DAT4R/L
Selected channel, fifth conversion result
AD0DAT5R/L
Selected channel, sixth conversion result
AD0DAT6R/L
Selected channel, seventh conversion result
AD0DAT7R/L
Selected channel, eighth conversion result
Auto scan, single conversion mode
Any combination of the eight input channels can be selected for conversion by setting a
channel’s respective bit in the ADINS register. A single conversion of each selected input
will be performed and the result placed in the result register pair which corresponds to the
selected input channel (see Table 7). The user may select whether an interrupt, if enabled,
will be generated after either the first four conversions have occurred or all selected
channels have been converted. If the user selects to generate an interrupt after the first
four input channels have been converted, a second interrupt will be generated after the
remaining input channels have been converted. If only a single channel is selected this is
equivalent to single channel, single conversion mode. The channels are converted from
LSB to MSB order (in ADINS). This mode is selected by setting the SCAN0 bit in the
ADMODA register.
3.2.1.4
Auto scan, continuous conversion mode
Any combination of the eight input channels can be selected for conversion by setting a
channel’s respective bit in the ADINS register. A conversion of each selected input will be
performed and the result placed in the result register pair which corresponds to the
selected input channel (See Table 7). The user may select whether an interrupt, if
enabled, will be generated after either the first four conversions have occurred or all
selected channels have been converted. If the user selects to generate an interrupt after
the four input channels have been converted, a second interrupt will be generated after
the remaining input channels have been converted. After all selected channels have been
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converted, the process will repeat starting with the first selected channel. Additional
conversion results will again cycle through the eight result register pairs, overwriting the
previous results. Continuous conversions continue until terminated by the user. The
channels are converted from LSB to MSB order (in ADINS). This mode is selected by
setting the BURST0 bit in the ADMODA register.
3.2.1.5
Dual channel, continuous conversion mode
This is a variation of the auto scan continuous conversion mode where conversion occurs
on two user-selectable inputs. Any combination of two of the eight input channels can be
selected for conversion. The result of the conversion of the first channel is placed in the
result register pair, AD0DAT0R and AD0DAT0L. The result of the conversion of the second
channel is placed in result register pair, AD0DAT1R and AD0DAT1L. The first channel is
again converted and its result stored in AD0DAT2R and AD0DAT2L. The second channel
is again converted and its result placed in AD0DAT3R and AD0DAT3L, etc. (see Table 9).
An interrupt is generated, if enabled, after every set of four or eight conversions (user
selectable). This mode is selected by setting the SCC0 bit in the ADMODA register.
Table 9:
3.2.1.6
Result registers and conversion results for dual channel, continuous conversion
mode
Result register
Contains
AD0DAT0R/L
First channel, first conversion result
AD0DAT1R/L
Second channel, first conversion result
AD0DAT2R/L
First channel, second conversion result
AD0DAT3R/L
Second channel, second conversion result
AD0DAT4R/L
First channel, third conversion result
AD0DAT5R/L
Second channel, third conversion result
AD0DAT6R/L
First channel, fourth conversion result
AD0DAT7R/L
Second channel, fourth conversion result
Single step mode
This special mode allows ‘single-stepping’ in an auto scan conversion mode. Any
combination of the eight input channels can be selected for conversion. After each
channel is converted, an interrupt is generated, if enabled, and the A/D waits for the next
start condition. The result of each channel is placed in the result register which
corresponds to the selected input channel (See Table 7). May be used with any of the start
modes. This mode is selected by clearing the BURST0, SCC0, and SCAN0 bits in the
ADMODA register.
3.2.2 Conversion mode selection bits
The A/D uses three bits in ADMODA to select the conversion mode. These mode bits are
summarized in Table 10,below. Combinations of the three bits, other than the
combinations shown, are undefined.
Table 10:
Conversion mode bits
Burst0
SCC0
Scan0
ADC0 conversion mode
0
0
0
Single step
0
0
1
Fixed channel, single
Auto scan, single
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Table 10:
Conversion mode bits …continued
Burst0
SCC0
Scan0
ADC0 conversion mode
0
1
0
Fixed channel, continuous
Dual channel, continuous
1
0
0
Auto scan, continuous
3.2.3 Conversion start modes
3.2.3.1
Timer triggered start
An A/D conversion is started by the overflow of Timer 0. Once a conversion has started,
additional Timer 0 triggers are ignored until the conversion has completed. The Timer
triggered start mode is available in all A/D operating modes.This mode is selected by the
TMMx bit and the ADCS01 and ADCS00 bits (see Table 12 and Table 14).
3.2.3.2
Start immediately
Programming this mode immediately starts a conversion.This start mode is available in all
A/D operating modes.This mode is selected by setting the ADCS01 and ADCS00 bits in
the ADCON0 register (See Table 12 and Table 14).
3.2.3.3
Edge triggered
An A/D conversion is started by rising or falling edge of P1.4. Once a conversion has
started, additional edge triggers are ignored until the conversion has completed. The edge
triggered start mode is available in all A/D operating modes.This mode is selected by
setting the ADCS01 and ADCS00 bits in the ADCON0 register (See Table 12 and
Table 14).
3.2.4 Stopping and restarting conversions
An A/D conversion or set of conversions can be stopped by clearing the ADCS01 and
ADCS00 bits in ADCON0 (and also theTMM0 bit in ADCON0 if the conversion was started
in Timer triggered mode). Prior to resuming conversions, the user will need to reset the
input multiplexer to the first user specified channel. This can be accomplished by writing
the ADINS register with the desired channels.
3.2.5 Boundary limits interrupt
The A/D converter has both a high and low boundary limit register. The user may select
whether an interrupt is generated when the conversion result is within (or equal to) the
high and low boundary limits or when the conversion result is outside the boundary limits.
An interrupt will be generated, if enabled, if the result meets the selected interrupt criteria.
The boundary limit may be disabled by clearing the boundary limit interrupt enable.
An early detection mechanism exists when the interrupt criteria has been selected to be
outside the boundary limits. In this case, after the four MSBs have been converted, these
four bits are compared with the four MSBs of the boundary high and low registers. If the
four MSBs of the conversion meet the interrupt criteria (i.e.- outside the boundary limits)
an interrupt will be generated, if enabled. If the four MSBs do not meet the interrupt
criteria, the boundary limits will again be compared after all 8 MSBs have been converted.
The boundary status register (BNDSTA0) flags the channels which caused a boundary
interrupt.
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3.2.6 Clock divider
The A/D converter requires that its internal clock source be in the range of 320 kHz to
9 MHz to maintain accuracy. A programmable clock divider that divides the clock from 1 to
8 is provided for this purpose (See Table 16).
3.2.7 I/O pins used with ADC functions
The analog input pins maybe be used as either digital I/O or as inputs to A/D and thus
have a digital input and output function. In order to give the best analog performance, pins
that are being used with the ADC should have their digital outputs and inputs disabled and
have the 5V tolerance disconnected. Digital outputs are disabled by putting the port pins
into the input-only mode as described in the Port Configurations section (see Table 24).
Digital inputs will be disconnected automatically from these pins when the pin has been
selected by setting its corresponding bit in the ADINS register and its corresponding A/D
has been enabled
When used as digital I/O these pins are 5 V tolerant. If selected as input signals in ADINS,
these pins will be 3V tolerant if the corresponding A/D is enabled and the device is not in
power down. Otherwise the pin will remain 5V tolerant. Please refer to the P89LPC938
data sheet for specifications.
3.2.8 Power-down and Idle mode
In Idle mode the A/D converter, if enabled, will continue to function and can cause the
device to exit Idle mode when the conversion is completed if the A/D interrupt is enabled.
In Power-down mode or Total Power-down mode, the A/D does not function. If the A/D is
enabled, it will consume power. Power can be reduced by disabling the A/D.
Table 11:
A/D Control register 0 (ADCON0 - address 97h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
ENBI0
ENADCI0
TMM0
EDGE0
ADCI0
ENADC0
ADCS01
ADCS00
Reset
0
0
0
0
0
0
0
0
Table 12:
A/D Control register 0 (ADCON0 - address 97h) bit description
Bit
Symbol
Description
1:0
ADCS01,ADCS00 A/D start mode bits, see below.
00 — Timer Trigger Mode when TMM0 = 1. Conversions starts on overflow of Timer
0. When TMM0 =0, no start occurs (stop mode).
01 — Immediate Start Mode. Conversion starts immediately.
10 — Edge Trigger Mode. Conversion starts when edge condition defined by bit
EDGE0 occurs.
2
ENADC0
Enable ADC0. When set = 1, enables ADC0, when = 0, the ADC is in power-down.
3
ADCI0
A/D Conversion complete Interrupt 0. Set when any conversion or set of multiple
conversions has completed. Cleared by software.
4
EDGE0
An edge conversion start is triggered by a falling edge on P1.4 when EDGE0 =0
while in edge-triggered mode. An edge conversion start is triggered by a rising edge
on P1.4 when EDGE0 =1 while in edge-triggered mode.
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Table 12:
A/D Control register 0 (ADCON0 - address 97h) bit description …continued
Bit
Symbol
Description
5
TMM0
Timer Trigger Mode 0. Selects either stop mode (TMM0 = 0) or timer trigger mode
(TMM0 = 1) when the ADCS01 and ADCS00 bits = 00.
6
ENADCI0
Enable A/D Conversion complete Interrupt 0. When set, will cause an interrupt if the
ADCI0 flag is set and the A/D interrupt is enabled.
7
ENBI0
Enable A/D boundary interrupt 0. When set, will cause an interrupt if the boundary
interrupt 0 flag, BNDI0, is set and the A/D interrupt is enabled.
Table 13:
A/D Mode register A (ADMODA - address 0C0h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
BNDI0
BURST0
SCC0
SCAN0
-
-
-
-
Reset
0
0
0
0
0
0
0
0
Table 14:
A/D Mode register A (ADMODA - address 0C0h) bit description
Bit
Symbol
Description
0:3
-
Reserved.
4
SCAN0
When = 1, selects single conversion mode (auto scan or fixed channel).
5
SCC0
When = 1, selects fixed and dual channel, continuous conversion modes.
6
BURST0
When = 1, selects auto scan, continuous conversion mode.
7
BNDI0
ADC0 boundary interrupt flag. When set, indicates that the converted result is
inside/outside of the range defined by the ADC0 boundary registers.
Table 15:
A/D Mode register B (ADMODB - address A1h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
CLK2
CLK1
CLK0
INBND0
-
-
BSA0
FCIIS
Reset
0
0
0
0
0
0
0
0
Table 16:
A/D Mode register B (ADMODB - address A1h) bit description
Bit
Symbol
Description
0
FCIIS
Four conversion intermediate interrupt select. When =1, will generate an interrupt
after four conversions in fixed channel or dual channel continuous modes. In any of
the scan modes setting this bit will generate an interrupt after the fourth conversion
if the number of channels selected is greater than four.
1
BSA0
ADC0 Boundary Select All. When =1, BNDI0 will be set if any ADC0 input exceeds
the boundary limits. When = 0, BNDI0 will be set only if the AD00 input exceeded
the boundary limits.
2:3
-
Reserved
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Table 16:
A/D Mode register B (ADMODB - address A1h) bit description …continued
Bit
Symbol
Description
4
INBND0
When set = 1, generates an interrupt if the conversion result is inside or equal to the
boundary limits. When cleared = 0, generates an interrupt if the conversion result is
outside the boundary limits.
7:5
CLK2,CLK1,CLK0 Clock divider to produce the ADC clock. Divides CCLK by the value indicated below.
The resulting ADC clock should be 9 MHz or less. A minimum of 320 kHz is required
to maintain A/D accuracy.
CLK2:0 — Divisor
000 — 1
001 — 2
010 — 3
011 — 4
011 — 5
011 — 6
011 — 7
011 — 8
Table 17:
A/D Input select (ADINS - address A3h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
AIN07
AIN06
AIN05
AIN04
AIN03
AIN02
AIN01
AIN00
Reset
0
0
0
0
0
0
0
0
Table 18:
A/D Input select (ADINS - address A3h) bit description
Bit
Symbol
Description
0
AIN00
When set, enables the AD00 pin for sampling and conversion.
1
AIN01
When set, enables the AD01 pin for sampling and conversion.
2
AIN02
When set, enables the AD02 pin for sampling and conversion.
3
AIN03
When set, enables the AD03 pin for sampling and conversion.
4
AIN04
When set, enables the AD04 pin for sampling and conversion.
5
AIN05
When set, enables the AD05 pin for sampling and conversion.
6
AIN06
When set, enables the AD06 pin for sampling and conversion.
7
AIN07
When set, enables the AD07 pin for sampling and conversion.
Table 19:
Boundary status register 0 (BNDSTA0 - address FFEDh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
BST07
BST06
BST05
BST04
BST03
BST02
BST01
BST00
Reset
0
0
0
0
0
0
0
0
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Table 20:
Boundary status register 0 (BNDSTA0 - address FFEDh) bit description
Bit
Symbol
Description
0
BST00
When set, indicates that conversion result for the AD00 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
1
BST01
When set, indicates that conversion result for the AD01 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
2
BST02
When set, indicates that conversion result for the AD02 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
3
BST03
When set, indicates that conversion result for the AD03 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
4
BST04
When set, indicates that conversion result for the AD04 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
5
BST05
When set, indicates that conversion result for the AD05 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
6
BST06
When set, indicates that conversion result for the AD06 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
7
BST07
When set, indicates that conversion result for the AD07 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
4. Interrupts
The P89LPC938 uses a four priority level interrupt structure. This allows great flexibility in
controlling the handling of the P89LPC938’s 15 interrupt sources.
Each interrupt source can be individually enabled or disabled by setting or clearing a bit in
the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a global
enable bit, EA, which enables all interrupts.
Each interrupt source can be individually programmed to one of four priority levels by
setting or clearing bits in the interrupt priority registers IP0, IP0H, IP1, and IP1H. An
interrupt service routine in progress can be interrupted by a higher priority interrupt, but
not by another interrupt of the same or lower priority. The highest priority interrupt service
cannot be interrupted by any other interrupt source. If two requests of different priority
levels are received simultaneously, the request of higher priority level is serviced.
If requests of the same priority level are pending at the start of an instruction cycle, an
internal polling sequence determines which request is serviced. This is called the
arbitration ranking. Note that the arbitration ranking is only used for pending requests of
the same priority level. Table 22 summarizes the interrupt sources, flag bits, vector
addresses, enable bits, priority bits, arbitration ranking, and whether each interrupt may
wake-up the CPU from a Power-down mode.
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4.1 Interrupt priority structure
Table 21:
Interrupt priority level
Priority bits
IPxH
IPx
Interrupt priority level
0
0
Level 0 (lowest priority)
0
1
Level 1
1
0
Level 2
1
1
Level 3
There are four SFRs associated with the four interrupt levels: IP0, IP0H, IP1, IP1H. Every
interrupt has two bits in IPx and IPxH (x = 0, 1) and can therefore be assigned to one of
four levels, as shown in Table 22.
The P89LPC938 has two external interrupt inputs in addition to the Keypad Interrupt
function. The two interrupt inputs are identical to those present on the standard 80C51
microcontrollers.
These external interrupts can be programmed to be level-triggered or edge-triggered by
clearing or setting bit IT1 or IT0 in Register TCON. If ITn = 0, external interrupt n is
triggered by a low level detected at the INTn pin. If ITn = 1, external interrupt n is edge
triggered. In this mode if consecutive samples of the INTn pin show a high level in one
cycle and a low level in the next cycle, interrupt request flag IEn in TCON is set, causing
an interrupt request.
Since the external interrupt pins are sampled once each machine cycle, an input high or
low level should be held for at least one machine cycle to ensure proper sampling. If the
external interrupt is edge-triggered, the external source has to hold the request pin high
for at least one machine cycle, and then hold it low for at least one machine cycle. This is
to ensure that the transition is detected and that interrupt request flag IEn is set. IEn is
automatically cleared by the CPU when the service routine is called.
If the external interrupt is level-triggered, the external source must hold the request active
until the requested interrupt is generated. If the external interrupt is still asserted when the
interrupt service routine is completed, another interrupt will be generated. It is not
necessary to clear the interrupt flag IEn when the interrupt is level sensitive, it simply
tracks the input pin level.
If an external interrupt has been programmed as level-triggered and is enabled when the
P89LPC938 is put into Power-down mode or Idle mode, the interrupt occurrence will
cause the processor to wake-up and resume operation. Refer to Section 6.3 “Power
reduction modes” for details.
4.2 External Interrupt pin glitch suppression
Most of the P89LPC938 pins have glitch suppression circuits to reject short glitches
(please refer to the P89LPC938 data sheet, Dynamic characteristics for glitch filter
specifications). However, pins SDA/INT0/P1.3 and SCL/T0/P1.2 do not have the glitch
suppression circuits. Therefore, INT1 has glitch suppression while INT0 does not.
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Table 22:
Summary of interrupts
Description
Interrupt flag
bit(s)
Vector
address
Interrupt enable
bit(s)
Interrupt
priority
Arbitration
ranking
Powerdown
wake-up
External interrupt 0
IE0
0003h
EX0 (IEN0.0)
IP0H.0, IP0.0
1 (highest)
Yes
Timer 0 interrupt
TF0
000Bh
ET0 (IEN0.1)
IP0H.1, IP0.1
4
No
External interrupt 1
IE1
0013h
EX1 (IEN0.2)
IP0H.2, IP0.2
7
Yes
Timer 1 interrupt
TF1
001Bh
ET1 (IEN0.3)
IP0H.3, IP0.3
10
No
Serial port Tx and Rx
TI and RI
0023h
ES/ESR (IEN0.4)
IP0H.4, IP0.4
13
No
Serial port Rx
RI
Brownout detect
BOF
002Bh
EBO (IEN0.5)
IP0H.5, IP0.5
2
Yes
Watchdog timer/Real-time
clock
WDOVF/RTCF
0053h
EWDRT (IEN0.6)
IP0H.6, IP0.6
3
Yes
I2C interrupt
SI
0033h
EI2C (IEN1.0)
IP0H.0, IP0.0
5
No
KBI interrupt
KBIF
003Bh
EKBI (IEN1.1)
IP0H.0, IP0.0
8
Yes
Comparators 1 and 2
interrupts
CMF1/CMF2
0043h
EC (IEN1.2)
IP0H.0, IP0.0
11
Yes
SPI interrupt
SPIF
004Bh
ESPI (IEN1.3)
IP1H.3, IP1.3
14
No
005Bh
ECCU(IEN1.4)
IP1H.4, IP1.4
6
No
006Bh
EST (IEN1.6)
IP0H.0, IP0.0
12
No
0073h
EAD (IEN1.7)
IP1H.7, IP1.7
15
No
0083h
EADC (IEN2.1)
IP2H.1, IP2.1
16 (lowest)
No
Capture/Compare Unit
Serial port Tx
TI
Data EEPROM
A/D converter
ADCI0, BNDI1
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IE0
EX0
IE1
EX1
BOF
EBO
RTCF
ERTC
(RTCCON.1)
WDOVF
wake-up
(if in power-down)
KBIF
EKBI
EWDRT
CMF2
CMF1
EC
EA (IE0.7)
TF0
ET0
TF1
ET1
TI & RI/RI
ES/ESR
TI
EST
interrupt
to CPU
SI
EI2C
SPIF
ESPI
any CCU interrupt(1)
ECCU
EEIF
EIEE
ENADCI0
ADCI0
ENBI1
BNDI1
EADC
002aab104
(1) See Section 10 “Capture/Compare Unit (CCU)”.
Fig 9. Interrupt sources, interrupt enables, and power-down wake-up sources.
5. I/O ports
The P89LPC938 has four I/O ports: Port 0, Port 1, Port 2, and Port 3. Ports 0, 1, and 2 are
8-bit ports and Port 3 is a 2-bit port. The exact number of I/O pins available depends upon
the clock and reset options chosen (see Table 23).
Table 23:
Number of I/O pins available
Clock source
Reset option
On-chip oscillator or watchdog
oscillator
No external reset (except during power up) 26
External RST pin supported
Number of I/O
pins
25
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Table 23:
Number of I/O pins available …continued
Clock source
Reset option
Number of I/O
pins
External clock input
No external reset (except during power up) 25
External RST pin supported[1]
24
Low/medium/high speed oscillator No external reset (except during power up) 24
(external crystal or resonator)
23
External RST pin supported[1]
[1]
Required for a clock frequency above 12 MHz.
5.1 Port configurations
All but three I/O port pins on the P89LPC938 may be configured by software to one of four
types on a pin-by-pin basis, as shown in Table 24. These are: quasi-bidirectional
(standard 80C51 port outputs), push-pull, open drain, and input-only. Two configuration
registers for each port select the output type for each port pin.
P1.5 (RST) can only be an input and cannot be configured.
P1.2 (SCL/T0) and P1.3 (SDA/INT0) may only be configured to be either input-only or
open drain.
Table 24:
Port output configuration settings
PxM1.y
PxM2.y
Port output mode
0
0
Quasi-bidirectional
0
1
Push-pull
1
0
Input only (high-impedance)
1
1
Open drain
5.2 Quasi-bidirectional output configuration
Quasi-bidirectional outputs can be used both as an input and output without the need to
reconfigure the port. This is possible because when the port outputs a logic high, it is
weakly driven, allowing an external device to pull the pin low. When the pin is driven low, it
is driven strongly and able to sink a large current. There are three pull-up transistors in the
quasi-bidirectional output that serve different purposes.
One of these pull-ups, called the ‘very weak’ pull-up, is turned on whenever the port latch
for the pin contains a logic 1. This very weak pull-up sources a very small current that will
pull the pin high if it is left floating.
A second pull-up, called the ‘weak’ pull-up, is turned on when the port latch for the pin
contains a logic 1 and the pin itself is also at a logic 1 level. This pull-up provides the
primary source current for a quasi-bidirectional pin that is outputting a 1. If this pin is
pulled low by an external device, the weak pull-up turns off, and only the very weak pull-up
remains on. In order to pull the pin low under these conditions, the external device has to
sink enough current to overpower the weak pull-up and pull the port pin below its input
threshold voltage.
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The third pull-up is referred to as the ‘strong’ pull-up. This pull-up is used to speed up
low-to-high transitions on a quasi-bidirectional port pin when the port latch changes from a
logic 0 to a logic 1. When this occurs, the strong pull-up turns on for two CPU clocks
quickly pulling the port pin high.
The quasi-bidirectional port configuration is shown in Figure 10.
Although the P89LPC938 is a 3 V device most of the pins are 5 V-tolerant. If 5 V is applied
to a pin configured in quasi-bidirectional mode, there will be a current flowing from the pin
to VDD causing extra power consumption. Therefore, applying 5 V to pins configured in
quasi-bidirectional mode is discouraged.
A quasi-bidirectional port pin has a Schmitt-triggered input that also has a glitch
suppression circuit
(Please refer to the P89LPC938 data sheet, Dynamic characteristics for glitch filter
specifications).
VDD
2 CPU
CLOCK DELAY
P
P
strong
very P
weak
weak
port
pin
port latch
data
input
data
glitch rejection
002aaa914
Fig 10. Quasi-bidirectional output.
5.3 Open drain output configuration
The open drain output configuration turns off all pull-ups and only drives the pull-down
transistor of the port pin when the port latch contains a logic 0. To be used as a logic
output, a port configured in this manner must have an external pull-up, typically a resistor
tied to VDD. The pull-down for this mode is the same as for the quasi-bidirectional mode.
The open drain port configuration is shown in Figure 11.
An open drain port pin has a Schmitt-triggered input that also has a glitch suppression
circuit.
Please refer to the P89LPC938 data sheet, Dynamic characteristics for glitch filter
specifications.
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port
pin
port latch
data
input
data
glitch rejection
002aaa915
Fig 11. Open drain output.
5.4 Input-only configuration
The input port configuration is shown in Figure 12. It is a Schmitt-triggered input that also
has a glitch suppression circuit.
(Please refer to the P89LPC938 data sheet, Dynamic characteristics for glitch filter
specifications).
input
data
port
pin
glitch rejection
002aaa916
Fig 12. Input only.
5.5 Push-pull output configuration
The push-pull output configuration has the same pull-down structure as both the open
drain and the quasi-bidirectional output modes, but provides a continuous strong pull-up
when the port latch contains a logic 1. The push-pull mode may be used when more
source current is needed from a port output.
The push-pull port configuration is shown in Figure 13.
A push-pull port pin has a Schmitt-triggered input that also has a glitch suppression
circuit.
(Please refer to the P89LPC938 data sheet, Dynamic characteristics for glitch filter
specifications).
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VDD
P
strong
port latch
data
N
input
data
port
pin
glitch rejection
002aaa917
Fig 13. Push-pull output.
5.6 Port 0 and Analog Comparator functions
The P89LPC938 incorporates two Analog Comparators. In order to give the best analog
performance and minimize power consumption, pins that are being used for analog
functions must have both the digital outputs and digital inputs disabled.
Digital outputs are disabled by putting the port pins into the input-only mode as described
in the Port Configurations section (see Figure 12).
Digital inputs on Port 0 may be disabled through the use of the PT0AD register. Bits 1
through 5 in this register correspond to pins P0.1 through P0.5 of Port 0, respectively.
Setting the corresponding bit in PT0AD disables that pin’s digital input. Port bits that have
their digital inputs disabled will be read as 0 by any instruction that accesses the port.
On any reset, PT0AD bits 1 through 5 default to logic 0s to enable the digital functions.
5.7 Additional port features
After power-up, all pins are in Input-Only mode. Please note that this is different from
the LPC76x series of devices.
• After power-up, all I/O pins except P1.5, may be configured by software.
• Pin P1.5 is input only. Pins P1.2 and P1.3 are configurable for either input-only or
open drain.
Every output on the P89LPC938 has been designed to sink typical LED drive current.
However, there is a maximum total output current for all ports which must not be
exceeded. Please refer to the P89LPC938 data sheet for detailed specifications.
All ports pins that can function as an output have slew rate controlled outputs to limit noise
generated by quickly switching output signals. The slew rate is factory-set to
approximately 10 ns rise and fall times.
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Table 25:
Port output configuration
Port pin
Configuration SFR bits
PxM1.y
PxM2.y
Alternate usage
P0.0
P0M1.0
P0M2.0
KBIO, CMP2, AD05
Notes
P0.1
P0M1.1
P0M2.1
P0.2
P0M1.2
P0M2.2
P0.3
P0M1.3
P0M2.3
KBI1, CIN2B, AD00 Refer to Section 5.6 “Port 0 and
KBI2, CIN2A, AD01 Analog Comparator functions” for
usage as analog inputs.
KBI3, CIN1B, AD02
P0.4
P0M1.4
P0M2.4
KBI4, CIN1A, AD03
P0.5
P0M1.5
P0M2.5
KBI5, CMPREF
P0.6
P0M1.6
P0M2.6
KBI6, CMP1
P0.7
P0M1.7
P0M2.7
KBI7, T1
P1.0
P1M1.0
P1M2.0
TXD
P1.1
P1M1.1
P1M2.1
RXD
P1.2
P1M1.2
P1M2.2
T0, SCL
Input-only or open-drain
input-only or open-drain
P1.3
P1M1.3
P1M2.3
INTO, SDA
P1.4
P1M1.4
P1M2.4
INT1
P1.5
P1M1.5
P1M2.5
RST
P1.6
P1M1.6
P1M2.6
OCB
P1.7
P1M1.7
P1M2.7
OCC, AD04
P2.0
P1M1.0
P1M2.0
ICB, AD07
P2.1
P1M1.1
P1M2.1
OCD, AD06
P2.2
P1M1.2
P1M2.2
MOSI
P2.3
P1M1.3
P1M2.3
MISO
P2.4
P1M1.4
P1M2.4
SS
P2.5
P1M1.5
P1M2.5
SPICLK
P2.6
P1M1.6
P1M2.6
OCA
P2.7
P1M1.7
P1M2.7
ICA
P3.0
P3M1.0
P3M2.0
CLKOUT, XTAL2
P3.1
P3M1.1
P3M2.1
XTAL1
6. Power monitoring functions
The P89LPC938 incorporates power monitoring functions designed to prevent incorrect
operation during initial power-on and power loss or reduction during operation. This is
accomplished with two hardware functions: Power-on Detect and Brownout Detect.
6.1 Brownout detection
The Brownout Detect function determines if the power supply voltage drops below a
certain level. The default operation for a Brownout Detection is to cause a processor reset.
However, it may alternatively be configured to generate an interrupt by setting the BOI
(PCON.4) bit and the EBO (IEN0.5) bit.
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Enabling and disabling of Brownout Detection is done via the BOPD (PCON.5) bit, bit field
PMOD1/PMOD0 (PCON[1:0]) and user configuration bit BOE (UCFG1.5). If BOE is in an
unprogrammed state, brownout is disabled regardless of PMOD1/PMOD0 and BOPD. If
BOE is in a programmed state, PMOD1/PMOD0 and BOPD will be used to determine
whether Brownout Detect will be disabled or enabled. PMOD1/PMOD0 is used to select
the power reduction mode. If PMOD1/PMOD0 = ‘11’, the circuitry for the Brownout
Detection is disabled for lowest power consumption. BOPD defaults to logic 0, indicating
brownout detection is enabled on power-on if BOE is programmed.
If Brownout Detection is enabled, the brownout condition occurs when VDD falls below the
Brownout trip voltage, VBO (see P89LPC938 data sheet, Static characteristics), and is
negated when VDD rises above VBO. If the P89LPC938 device is to operate with a power
supply that can be below 2.7 V, BOE should be left in the unprogrammed state so that the
device can operate at 2.4 V, otherwise continuous brownout reset may prevent the device
from operating.
If Brownout Detect is enabled (BOE programmed, PMOD1/PMOD0 ≠ ‘11’, BOPD = 0),
BOF (RSTSRC.5) will be set when a brownout is detected, regardless of whether a reset
or an interrupt is enabled. BOF will stay set until it is cleared in software by writing a
logic 0 to the bit. Note that if BOE is unprogrammed, BOF is meaningless. If BOE is
programmed, and a initial power-on occurs, BOF will be set in addition to the power-on
flag (POF - RSTSRC.4).
For correct activation of Brownout Detect, certain VDD rise and fall times must be
observed. Please see the data sheet for specifications.
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Table 26:
Brownout options[1]
BOE
(UCFG1.5)
PMOD1/
PMOD0
(PCON[1:0])
BOPD
(PCON.5)
BOI
(PCON.4)
EBO
(IEN0.5)
EA (IEN0.7)
Description
0 (erased)
XX
X
X
X
X
1(program
med)
11 (total
power-down)
X
X
X
X
Brownout disabled. VDD
operating range is 2.4 V to 3.6 V.
X
X
X
Brownout disabled. VDD
operating range is 2.4 V to 3.6 V.
However, BOPD is default to
logic 0 upon power-up.
X
X
Brownout reset enabled. VDD
operating range is 2.7 V to 3.6 V.
Upon a brownout reset, BOF
(RSTSRC.5) will be set to
indicate the reset source. BOF
can be cleared by writing a
logic 0 to the bit.
1 (global
interrupt
enable)
Brownout interrupt enabled. VDD
operating range is 2.7 V to 3.6 V.
Upon a brownout interrupt, BOF
(RSTSRC.5) will be set. BOF can
be cleared by writing a logic 0 to
the bit.
0
X
X
0
Both brownout reset and
interrupt disabled. VDD operating
range is 2.4 V to 3.6 V. However,
BOF (RSTSRC.5) will be set
when VDD falls to the Brownout
Detection trip point. BOF can be
cleared by writing a logic 0 to the
bit.
≠ 11 (any mode 1 (brownout
other than total detect
power-down)
power-down)
0 (brownout
0 (brownout
detect active) detect
generates
reset)
1 (brownout
1 (enable
detect
brownout
generates an interrupt)
interrupt)
[1]
Cannot be used with operation above 12 MHz as this requires VDD of 3.0 V or above.
6.2 Power-on detection
The Power-On Detect has a function similar to the Brownout Detect, but is designed to
work as power initially comes up, before the power supply voltage reaches a level where
the Brownout Detect can function. The POF flag (RSTSRC.4) is set to indicate an initial
power-on condition. The POF flag will remain set until cleared by software by writing a
logic 0 to the bit. Note that if BOE (UCFG1.5) is programmed, BOF (RSTSRC.5) will be
set when POF is set. If BOE is unprogrammed, BOF is meaningless.
6.3 Power reduction modes
The P89LPC938 supports three different power reduction modes as determined by SFR
bits PCON[1:0] (see Table 27).
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Table 27:
Power reduction modes
PMOD1
PMOD0
Description
(PCON.1) (PCON.0)
0
0
Normal mode (default) - no power reduction.
0
1
Idle mode. The Idle mode leaves peripherals running in order to allow them to activate the
processor when an interrupt is generated. Any enabled interrupt source or reset may terminate Idle
mode.
1
0
Power-down mode:
The Power-down mode stops the oscillator in order to minimize power consumption.
The P89LPC938 exits Power-down mode via any reset, or certain interrupts - external pins
INT0/INT1, brownout Interrupt, keyboard, Real-time Clock/System Timer), watchdog, and
comparator trips. Waking up by reset is only enabled if the corresponding reset is enabled, and
waking up by interrupt is only enabled if the corresponding interrupt is enabled and the EA SFR bit
(IEN0.7) is set. External interrupts should be programmed to level-triggered mode to be used to exit
Power-down mode.
In Power-down mode the internal RC oscillator is disabled unless both the RC oscillator has been
selected as the system clock AND the RTC is enabled.
In Power-down mode, the power supply voltage may be reduced to the RAM keep-alive voltage
VRAM. This retains the RAM contents at the point where Power-down mode was entered. SFR
contents are not guaranteed after VDD has been lowered to VRAM, therefore it is recommended to
wake-up the processor via Reset in this situation. VDD must be raised to within the operating range
before the Power-down mode is exited.
When the processor wakes up from Power-down mode, it will start the oscillator immediately and
begin execution when the oscillator is stable. Oscillator stability is determined by counting 1024
CPU clocks after start-up when one of the crystal oscillator configurations is used, or 256 clocks
after start-up for the internal RC or external clock input configurations.
Some chip functions continue to operate and draw power during Power-down mode, increasing the
total power used during power-down. These include:
1
1
•
•
•
Brownout Detect
•
Real-time Clock/System Timer (and the crystal oscillator circuitry if this block is using it, unless
RTCPD, i.e., PCONA.7 is logic 1).
Watchdog Timer if WDCLK (WDCON.0) is logic 1.
Comparators (Note: Comparators can be powered down separately with PCONA.5 set to
logic 1 and comparators disabled);
Total Power-down mode: This is the same as Power-down mode except that the Brownout
Detection circuitry and the voltage comparators are also disabled to conserve additional power.
Note that a brownout reset or interrupt will not occur. Voltage comparator interrupts and Brownout
interrupt cannot be used as a wake-up source. The internal RC oscillator is disabled unless both
the RC oscillator has been selected as the system clock AND the RTC is enabled.
The following are the wake-up options supported:
•
Watchdog Timer if WDCLK (WDCON.0) is logic 1. Could generate Interrupt or Reset, either
one can wake up the device
•
•
•
External interrupts INTO/INT1 (when programmed to level-triggered mode).
Keyboard Interrupt
Real-time Clock/System Timer (and the crystal oscillator circuitry if this block is using it, unless
RTCPD, i.e., PCONA.7 is logic 1).
Note: Using the internal RC-oscillator to clock the RTC during power-down may result in relatively
high power consumption. Lower power consumption can be achieved by using an external low
frequency clock when the Real-time Clock is running during power-down.
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Table 28:
Power Control register (PCON - address 87h) bit allocation
Bit
7
6
5
4
Symbol
SMOD1
SMOD0
BOPD
Reset
0
0
0
Table 29:
3
2
1
0
BOI
GF1
GF0
PMOD1
PMOD0
0
0
0
0
0
Power Control register (PCON - address 87h) bit description
Bit
Symbol
Description
0
PMOD0
Power Reduction Mode (see Section 6.3)
1
PMOD1
2
GF0
General Purpose Flag 0. May be read or written by user software, but has no effect
on operation
3
GF1
General Purpose Flag 1. May be read or written by user software, but has no effect
on operation
4
BOI
Brownout Detect Interrupt Enable. When logic 1, Brownout Detection will generate a
interrupt. When logic 0, Brownout Detection will cause a reset
5
BOPD
Brownout Detect power-down. When logic 1, Brownout Detect is powered down and
therefore disabled. When logic 0, Brownout Detect is enabled. (Note: BOPD must
be logic 0 before any programming or erasing commands can be issued. Otherwise
these commands will be aborted.)
6
SMOD0
Framing Error Location:
•
•
7
Table 30:
SMOD1
When logic 0, bit 7 of SCON is accessed as SM0 for the UART.
When logic 1, bit 7 of SCON is accessed as the framing error status (FE) for the
UART
Double Baud Rate bit for the serial port (UART) when Timer 1 is used as the baud
rate source. When logic 1, the Timer 1 overflow rate is supplied to the UART. When
logic 0, the Timer 1 overflow rate is divided by two before being supplied to the
UART. (See Section 11)
Power Control register A (PCONA - address B5h) bit allocation
Bit
7
6
5
Symbol
RTCPD
DEEPD
VCPD
ADPD
I2PD
SPPD
SPD
CCUPD
Reset
0
0
0
0
0
0
0
0
Table 31:
4
3
2
1
0
Power Control register A (PCONA - address B5h) bit description
Bit
Symbol
Description
0
CCUPD
Compare/Capture Unit (CCU) power-down: When logic 1, the internal clock to the
CCU is disabled. Note that in either Power-down mode or Total Power-down mode,
the CCU clock will be disabled regardless of this bit. (Note: This bit is overridden by
the CCUDIS bit in FCFG1. If CCUDIS = 1, CCU is powered down.)
1
SPD
Serial Port (UART) power-down: When logic 1, the internal clock to the UART is
disabled. Note that in either Power-down mode or Total Power-down mode, the
UART clock will be disabled regardless of this bit.
2
SPPD
SPI power-down: When logic 1, the internal clock to the SPI is disabled. Note that in
either Power-down mode or Total Power-down mode, the SPI clock will be disabled
regardless of this bit.
3
I2PD
I2C power-down: When logic 1, the internal clock to the I2C-bus is disabled. Note
that in either Power-down mode or Total Power-down mode, the I2C clock will be
disabled regardless of this bit.
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Table 31:
Power Control register A (PCONA - address B5h) bit description …continued
Bit
Symbol
Description
4
ADPD
A/D converter power-down: When logic 1, the ADC is powered down.
5
VCPD
Analog Voltage Comparators power-down: When logic 1, the voltage comparators
are powered down. User must disable the voltage comparators prior to setting this
bit.
6
DEEPD
Data EEPROM power-down: When logic 1, the Data EEPROM is powered down.
Note that in either Power-down mode or Total Power-down mode, the Data
EEPROM will be powered down regardless of this bit.
7
RTCPD
Real-time Clock power-down: When logic 1, the internal clock to the Real-time
Clock is disabled.
7. Reset
The P1.5/RST pin can function as either an active low reset input or as a digital input,
P1.5. The RPE (Reset Pin Enable) bit in UCFG1, when set to 1, enables the external reset
input function on P1.5. When cleared, P1.5 may be used as an input pin.
Note: During a power-on sequence, The RPE selection is overridden and this pin will
always functions as a reset input. An external circuit connected to this pin should not hold
this pin low during a Power-on sequence as this will keep the device in reset. After
power-on this input will function either as an external reset input or as a digital input as
defined by the RPE bit. Only a power-on reset will temporarily override the selection
defined by RPE bit. Other sources of reset will not override the RPE bit.
Note: During a power cycle, VDD must fall below VPOR (see P89LPC938 data sheet, Static
characteristics) before power is reapplied, in order to ensure a power-on reset.
Note: When using an oscillator frequency above 12 MHz, the reset input function of P1.5
must be enabled. An external circuit is required to hold the device in reset at power-up
until VDD has reached its specified level. When system power is removed VDD will fall
below the minimum specified operating voltage. When using an oscillator frequency above
12 MHz, in some applications, an external brownout detect circuit may be required to hold
the device in reset when VDD falls below the minimum specified operating voltage.
Reset can be triggered from the following sources (see Figure 14):
•
•
•
•
•
•
External reset pin (during power-on or if user configured via UCFG1);
Power-on Detect;
Brownout Detect;
Watchdog Timer;
Software reset;
UART break detect reset.
For every reset source, there is a flag in the Reset Register, RSTSRC. The user can read
this register to determine the most recent reset source. These flag bits can be cleared in
software by writing a logic 0 to the corresponding bit. More than one flag bit may be set:
• During a power-on reset, both POF and BOF are set but the other flag bits are
cleared.
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• For any other reset, any previously set flag bits that have not been cleared will remain
set.
RPE (UCFG1.6)
RST pin
WDTE (UCFG1.7)
Watchdog timer reset
Software reset SRST (AUXR1.3)
chip reset
Power-on detect
UART break detect
EBRR (AUXR1.6)
Brownout detect reset
BOPD (PCON.5)
002aaa918
Fig 14. Block diagram of reset.
Table 32:
Reset Sources register (RSTSRC - address DFh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
BOF
POF
R_BK
R_WD
R_SF
R_EX
Reset[1]
x
x
1
1
0
0
0
0
[1]
The value shown is for a power-on reset. Other reset sources will set their corresponding bits.
Table 33:
Reset Sources register (RSTSRC - address DFh) bit description
Bit Symbol Description
0
R_EX
external reset Flag. When this bit is logic 1, it indicates external pin reset. Cleared by software by writing a
logic 0 to the bit or a Power-on reset. If RST is still asserted after the Power-on reset is over, R_EX will be set.
1
R_SF
software reset Flag. Cleared by software by writing a logic 0 to the bit or a Power-on reset
2
R_WD
Watchdog Timer reset flag. Cleared by software by writing a logic 0 to the bit or a Power-on reset.(NOTE:
UCFG1.7 must be = 1)
3
R_BK
break detect reset. If a break detect occurs and EBRR (AUXR1.6) is set to logic 1, a system reset will occur.
This bit is set to indicate that the system reset is caused by a break detect. Cleared by software by writing a
logic 0 to the bit or on a Power-on reset.
4
POF
Power-on Detect Flag. When Power-on Detect is activated, the POF flag is set to indicate an initial power-up
condition. The POF flag will remain set until cleared by software by writing a logic 0 to the bit. (Note: On a
Power-on reset, both BOF and this bit will be set while the other flag bits are cleared.)
5
BOF
Brownout Detect Flag. When Brownout Detect is activated, this bit is set. It will remain set until cleared by
software by writing a logic 0 to the bit. (Note: On a Power-on reset, both POF and this bit will be set while the
other flag bits are cleared.)
6:7 -
reserved
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7.1 Reset vector
Following reset, the P89LPC938 will fetch instructions from either address 0000h or the
Boot address. The Boot address is formed by using the Boot Vector as the high byte of the
address and the low byte of the address = 00h. The Boot address will be used if a UART
break reset occurs or the non-volatile Boot Status bit (BOOTSTAT.0) = 1, or the device has
been forced into ISP mode. Otherwise, instructions will be fetched from address 0000H.
8. Timers 0 and 1
The P89LPC938 has two general-purpose counter/timers which are upward compatible
with the 80C51 Timer 0 and Timer 1. Both can be configured to operate either as timers or
event counters (see Table 35). An option to automatically toggle the Tx pin upon timer
overflow has been added.
In the ‘Timer’ function, the timer is incremented every PCLK.
In the ‘Counter’ function, the register is incremented in response to a 1-to-0 transition on
its corresponding external input pin (T0 or T1). The external input is sampled once during
every machine cycle. When the pin is high during one cycle and low in the next cycle, the
count is incremented. The new count value appears in the register during the cycle
following the one in which the transition was detected. Since it takes two machine cycles
(four CPU clocks) to recognize a 1-to-0 transition, the maximum count rate is 1⁄4 of the
CPU clock frequency. There are no restrictions on the duty cycle of the external input
signal, but to ensure that a given level is sampled at least once before it changes, it should
be held for at least one full machine cycle.
The ‘Timer’ or ‘Counter’ function is selected by control bits TnC/T (x = 0 and 1 for Timers 0
and 1 respectively) in the Special Function Register TMOD. Timer 0 and Timer 1 have five
operating modes (modes 0, 1, 2, 3 and 6), which are selected by bit-pairs (TnM1, TnM0)
in TMOD and TnM2 in TAMOD. Modes 0, 1, 2 and 6 are the same for both
Timers/Counters. Mode 3 is different. The operating modes are described later in this
section.
Table 34:
Timer/Counter Mode register (TMOD - address 89h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
T1GATE
T1C/T
T1M1
T1M0
T0GATE
T0C/T
T0M1
T0M0
Reset
0
0
0
0
0
0
0
0
Table 35:
Timer/Counter Mode register (TMOD - address 89h) bit description
Bit Symbol
Description
0
T0M0
1
T0M1
Mode Select for Timer 0. These bits are used with the T0M2 bit in the TAMOD register to determine the
Timer 0 mode (see Table 37).
2
T0C/T
3
T0GATE Gating control for Timer 0. When set, Timer/Counter is enabled only while the INT0 pin is high and the TR0
control pin is set. When cleared, Timer 0 is enabled when the TR0 control bit is set.
Timer or Counter selector for Timer 0. Cleared for Timer operation (input from CCLK). Set for Counter
operation (input from T0 input pin).
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Table 35:
Timer/Counter Mode register (TMOD - address 89h) bit description …continued
Bit Symbol
Description
4
T1M0
5
T1M1
Mode Select for Timer 1. These bits are used with the T1M2 bit in the TAMOD register to determine the
Timer 1 mode (see Table 37).
6
T1C/T
7
T1GATE Gating control for Timer 1. When set, Timer/Counter is enabled only while the INT1 pin is high and the TR1
control pin is set. When cleared, Timer 1 is enabled when the TR1 control bit is set.
Table 36:
Timer or Counter Selector for Timer 1. Cleared for Timer operation (input from CCLK). Set for Counter
operation (input from T1 input pin).
Timer/Counter Auxiliary Mode register (TAMOD - address 8Fh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
--
-
-
T1M2
-
-
-
T0M2
Reset
x
x
x
0
x
x
x
0
Table 37:
Timer/Counter Auxiliary Mode register (TAMOD - address 8Fh) bit description
Bit Symbol
Description
0
Mode Select for Timer 0. These bits are used with the T0M2 bit in the TAMOD register to determine the
Timer 0 mode (see Table 37).
T0M2
1:3 -
reserved
4
Mode Select for Timer 1. These bits are used with the T1M2 bit in the TAMOD register to determine the
Timer 1 mode (see Table 37).
T1M2
The following timer modes are selected by timer mode bits TnM[2:0]:
000 — 8048 Timer ‘TLn’ serves as 5-bit prescaler. (Mode 0)
001 — 16-bit Timer/Counter ‘THn’ and ‘TLn’ are cascaded; there is no prescaler.(Mode 1)
010 — 8-bit auto-reload Timer/Counter. THn holds a value which is loaded into TLn when it overflows.
(Mode 2)
011 — Timer 0 is a dual 8-bit Timer/Counter in this mode. TL0 is an 8-bit Timer/Counter controlled by the
standard Timer 0 control bits. TH0 is an 8-bit timer only, controlled by the Timer 1 control bits (see text).
Timer 1 in this mode is stopped. (Mode 3)
100 — Reserved. User must not configure to this mode.
101 — Reserved. User must not configure to this mode.
110 — PWM mode (see Section 8.5).
111 — Reserved. User must not configure to this mode.
5:7 -
reserved
8.1 Mode 0
Putting either Timer into Mode 0 makes it look like an 8048 Timer, which is an 8-bit
Counter with a divide-by-32 prescaler. Figure 15 shows Mode 0 operation.
In this mode, the Timer register is configured as a 13-bit register. As the count rolls over
from all 1s to all 0s, it sets the Timer interrupt flag TFn. The count input is enabled to the
Timer when TRn = 1 and either TnGATE = 0 or INTn = 1. (Setting TnGATE = 1 allows the
Timer to be controlled by external input INTn, to facilitate pulse width measurements).
TRn is a control bit in the Special Function Register TCON (Table 39). The TnGATE bit is
in the TMOD register.
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The 13-bit register consists of all 8 bits of THn and the lower 5 bits of TLn. The upper 3
bits of TLn are indeterminate and should be ignored. Setting the run flag (TRn) does not
clear the registers.
Mode 0 operation is the same for Timer 0 and Timer 1. See Figure 15. There are two
different GATE bits, one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3).
8.2 Mode 1
Mode 1 is the same as Mode 0, except that all 16 bits of the timer register (THn and TLn)
are used. See Figure 16.
8.3 Mode 2
Mode 2 configures the Timer register as an 8-bit Counter (TLn) with automatic reload, as
shown in Figure 17. Overflow from TLn not only sets TFn, but also reloads TLn with the
contents of THn, which must be preset by software. The reload leaves THn unchanged.
Mode 2 operation is the same for Timer 0 and Timer 1.
8.4 Mode 3
When Timer 1 is in Mode 3 it is stopped. The effect is the same as setting TR1 = 0.
Timer 0 in Mode 3 establishes TL0 and TH0 as two separate 8-bit counters. The logic for
Mode 3 on Timer 0 is shown in Figure 18. TL0 uses the Timer 0 control bits: T0C/T,
T0GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting machine
cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the
‘Timer 1’ interrupt.
Mode 3 is provided for applications that require an extra 8-bit timer. With Timer 0 in Mode
3, an P89LPC938 device can look like it has three Timer/Counters.
Note: When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it into and
out of its own Mode 3. It can still be used by the serial port as a baud rate generator, or in
any application not requiring an interrupt.
8.5 Mode 6
In this mode, the corresponding timer can be changed to a PWM with a full period of 256
timer clocks (see Figure 19). Its structure is similar to mode 2, except that:
•
•
•
•
TFn (n = 0 and 1 for Timers 0 and 1 respectively) is set and cleared in hardware;
The low period of the TFn is in THn, and should be between 1 and 254, and;
The high period of the TFn is always 256−THn.
Loading THn with 00h will force the Tx pin high, loading THn with FFh will force the Tx
pin low.
Note that interrupt can still be enabled on the low to high transition of TFn, and that TFn
can still be cleared in software like in any other modes.
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Table 38:
Timer/Counter Control register (TCON) - address 88h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Reset
0
0
0
0
0
0
0
0
Table 39:
Timer/Counter Control register (TCON - address 88h) bit description
Bit Symbol
Description
0
IT0
Interrupt 0 Type control bit. Set/cleared by software to specify falling edge/low level triggered external
interrupts.
1
IE0
Interrupt 0 Edge flag. Set by hardware when external interrupt 0 edge is detected. Cleared by hardware
when the interrupt is processed, or by software.
2
IT1
Interrupt 1 Type control bit. Set/cleared by software to specify falling edge/low level triggered external
interrupts.
3
IE1
Interrupt 1 Edge flag. Set by hardware when external interrupt 1 edge is detected. Cleared by hardware
when the interrupt is processed, or by software.
4
TR0
Timer 0 Run control bit. Set/cleared by software to turn Timer/Counter 0 on/off.
5
TF0
Timer 0 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the processor
vectors to the interrupt routine, or by software. (except in mode 6, where it is cleared in hardware)
6
TR1
Timer 1 Run control bit. Set/cleared by software to turn Timer/Counter 1 on/off
7
TF1
Timer 1 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the interrupt
is processed, or by software (except in mode 6, see above, when it is cleared in hardware).
PCLK
Tn pin
overflow
C/T = 0
C/T = 1
control
TLn
(5-bits)
THn
(8-bits)
TFn
interrupt
toggle
TRn
Tn pin
Gate
INTn pin
ENTn
002aaa919
Fig 15. Timer/counter 0 or 1 in Mode 0 (13-bit counter).
PCLK
Tn pin
overflow
C/T = 0
C/T = 1
control
TLn
(8-bits)
THn
(8-bits)
TFn
interrupt
toggle
TRn
Tn pin
Gate
INTn pin
ENTn
002aaa920
Fig 16. Timer/counter 0 or 1 in mode 1 (16-bit counter).
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C/T = 0
PCLK
Tn pin
C/T = 1
overflow
TLn
(8-bits)
control
interrupt
TFn
reload
toggle
TRn
Tn pin
Gate
THn
(8-bits)
INTn pin
ENTn
002aaa921
Fig 17. Timer/counter 0 or 1 in Mode 2 (8-bit auto-reload).
C/T = 0
PCLK
T0 pin
C/T = 1
control
overflow
TL0
(8-bits)
interrupt
TF0
toggle
TR0
T0 pin
(P1.2 open drain)
Gate
INT0 pin
ENT0
(AUXR1.4)
Osc/2
control
overflow
TH0
(8-bits)
interrupt
TF1
toggle
TR1
T1 pin
(P0.7)
ENT1
(AUXR1.5)
002aaa922
Fig 18. Timer/counter 0 Mode 3 (two 8-bit counters).
C/T = 0
PCLK
control
TLn
(8-bits)
overflow
TFn
interrupt
reload THn on falling transition
and (256-THn) on rising transition
toggle
TRn
Tn pin
Gate
THn
(8-bits)
INTn pin
ENTn
002aaa923
Fig 19. Timer/counter 0 or 1 in mode 6 (PWM auto-reload).
8.6 Timer overflow toggle output
Timers 0 and 1 can be configured to automatically toggle a port output whenever a timer
overflow occurs. The same device pins that are used for the T0 and T1 count inputs and
PWM outputs are also used for the timer toggle outputs. This function is enabled by
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control bits ENT0 and ENT1 in the AUXR1 register, and apply to Timer 0 and Timer 1
respectively. The port outputs will be a logic 1 prior to the first timer overflow when this
mode is turned on. In order for this mode to function, the C/T bit must be cleared selecting
PCLK as the clock source for the timer.
9. Real-time clock system timer
The P89LPC938 has a simple Real-time Clock/System Timer that allows a user to
continue running an accurate timer while the rest of the device is powered down. The
Real-time Clock can be an interrupt or a wake-up source (see Figure 20).
The Real-time Clock is a 23-bit down counter. The clock source for this counter can be
either the CPU clock (CCLK) or the XTAL1-2 oscillator, provided that the XTAL1-2
oscillator is not being used as the CPU clock. If the XTAL1-2 oscillator is used as the CPU
clock, then the RTC will use CCLK as its clock source regardless of the state of the
RTCS1:0 in the RTCCON register. There are three SFRs used for the RTC:
RTCCON — Real-time Clock control.
RTCH — Real-time Clock counter reload high (bits 22 to 15).
RTCL — Real-time Clock counter reload low (bits 14 to 7).
The Real-time clock system timer can be enabled by setting the RTCEN (RTCCON.0) bit.
The Real-time Clock is a 23-bit down counter (initialized to all 0’s when RTCEN = 0) that is
comprised of a 7-bit prescaler and a 16-bit loadable down counter. When RTCEN is
written with logic 1, the counter is first loaded with (RTCH, RTCL, ‘1111111’) and will
count down. When it reaches all 0’s, the counter will be reloaded again with (RTCH,
RTCL, ‘1111111’) and a flag - RTCF (RTCCON.7) - will be set.
Power-on
reset
RTCH
RTCL
XTAL2
RTC Reset
XTAL1
Reload on underflow
MSB
LSB
LOW FREQ.
MED. FREQ.
HIGH FREQ.
7-bit prescaler
÷128
23-bit down counter
CCLK
internal
oscillators
Wake-up from power-down
Interrupt if enabled
(shared with WDT)
RTCF
RTCEN
RTCS1 RTCS2
RTC underflow flag
RTC enable
RTC clk select
ERTC
002aaa924
Fig 20. Real-time clock/system timer block diagram.
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9.1 Real-time clock source
RTCS1/RTCS0 (RTCCON[6:5]) are used to select the clock source for the RTC if either
the Internal RC oscillator or the internal WD oscillator is used as the CPU clock. If the
internal crystal oscillator or the external clock input on XTAL1 is used as the CPU clock,
then the RTC will use CCLK as its clock source.
9.2 Changing RTCS1/RTCS0
RTCS1/RTCS0 cannot be changed if the RTC is currently enabled (RTCCON.0 = 1).
Setting RTCEN and updating RTCS1/RTCS0 may be done in a single write to RTCCON.
However, if RTCEN = 1, this bit must first be cleared before updating RTCS1/RTCS0.
9.3 Real-time clock interrupt/wake-up
If ERTC (RTCCON.1), EWDRT (IEN1.0.6) and EA (IEN0.7) are set to logic 1, RTCF can
be used as an interrupt source. This interrupt vector is shared with the watchdog timer. It
can also be a source to wake-up the device.
9.4 Reset sources affecting the Real-time clock
Only power-on reset will reset the Real-time Clock and its associated SFRs to their default
state.
Table 40:
Real-time Clock/System Timer clock sources
FOSC2:0
RCCLK
RTCS1:0
RTC clock source
CPU clock source
000
0
00
High frequency crystal
High frequency crystal
/DIVM
01
10
1
11
High frequency crystal
/DIVM
00
High frequency crystal
Internal RC oscillator
01
10
001
0
11
Internal RC oscillator
00
Medium frequency crystal Medium frequency crystal
/DIVM
01
10
1
11
Medium frequency crystal
/DIVM
00
Medium frequency crystal Internal RC oscillator
01
10
11
Internal RC oscillator
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Table 40:
Real-time Clock/System Timer clock sources …continued
FOSC2:0
RCCLK
RTCS1:0
RTC clock source
CPU clock source
010
0
00
Low frequency crystal
Low frequency crystal
/DIVM
01
10
1
11
Low frequency crystal
/DIV
00
Low frequency crystal
Internal RC oscillator
01
10
011
0
1
100
0
1
11
Internal RC oscillator
00
High frequency crystal
01
Internal RC oscillator
Medium frequency crystal /DIVM
10
Low frequency crystal
11
Internal RC oscillator
/DIVM
00
High frequency crystal
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
00
01
High frequency crystal
Watchdog oscillator
Medium frequency crystal /DIVM
10
Low frequency crystal
11
Watchdog oscillator /DIVM
00
High frequency crystal
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
Internal RC oscillator
Internal RC oscillator
101
x
xx
undefined
undefined
110
x
xx
undefined
undefined
111
0
00
External clock input
External clock input
/DIVM
01
10
1
11
External clock input /DIVM
00
External clock input
Internal RC oscillator
01
10
11
Internal RC oscillator
Table 41:
Real-time Clock Control register (RTCCON - address D1h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
RTCF
RTCS1
RTCS0
-
-
-
ERTC
RTCEN
Reset
0
1
1
x
x
x
0
0
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Table 42:
Real-time Clock Control register (RTCCON - address D1h) bit description
Bit
Symbol
Description
0
RTCEN
Real-time Clock enable. The Real-time Clock will be enabled if this bit is logic 1.
Note that this bit will not power-down the Real-time Clock. The RTCPD bit
(PCONA.7) if set, will power-down and disable this block regardless of RTCEN.
1
ERTC
Real-time Clock interrupt enable. The Real-time Clock shares the same interrupt
as the watchdog timer. Note that if the user configuration bit WDTE (UCFG1.7)
is logic 0, the watchdog timer can be enabled to generate an interrupt. Users
can read the RTCF (RTCCON.7) bit to determine whether the Real-time Clock
caused the interrupt.
2:4
-
reserved
5
RTCS0
Real-time Clock source select (see Table 40).
6
RTCS1
7
RTCF
Real-time Clock Flag. This bit is set to logic 1 when the 23-bit Real-time Clock
reaches a count of logic 0. It can be cleared in software.
10. Capture/Compare Unit (CCU)
This unit features:
• A 16-bit timer with 16-bit reload on overflow
• Selectable clock (CCUCLK), with a prescaler to divide the clock source by any integer
between 1 and 1024.
• Four Compare / PWM outputs with selectable polarity
• Symmetrical / Asymmetrical PWM selection
• Seven interrupts with common interrupt vector (one Overflow, 2xCapture,
4xCompare), safe 16-bit read/write via shadow registers.
• Two Capture inputs with event counter and digital noise rejection filter
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16-BIT SHADOW REGISTER
TOR2H TO TOR2L
16-BIT SHADOW REGISTER
OCRxH TO OCRxL
16-BIT COMPARE
VALUE
OCD
OCC
OCB
TIMER > COMPARE
16-BIT TIMER RELOAD
REGISTER
OCA
COMPARE CHANNELS A TO D
OVERFLOW/
UNDERFLOW
16-BIT CAPTURE
REGISTER ICRxH, L
16-BIT UP/DOWN TIMER
WITH RELOAD
EVENT
COUNTER
FCOx
ICNFx
ICESx
ICB
NOISE
FILTER
EDGE
SELECT
ICA
10-BIT DIVIDER
INTERRUPT FLAG
TICF2x SET
4-BIT
DIVIDER
CAPTURE CHANNELS A, B
002aab009
32 × PLL
Fig 21. Capture Compare Unit block diagram.
10.1 CCU Clock (CCUCLK)
The CCU runs on the CCUCLK, which can be either PCLK in basic timer mode or the
output of a PLL (see Figure 21). The PLL is designed to use a clock source between
0.5 MHz to 1 MHz that is multiplied by 32 to produce a CCUCLK between 16 MHz and
32 MHz in PWM mode (asymmetrical or symmetrical). The PLL contains a 4-bit divider
(PLLDV3:0 bits in the TCR21 register) to help divide PCLK into a frequency between
0.5 MHz and 1 MHz
10.2 CCU Clock prescaling
This CCUCLK can further be divided down by a prescaler. The prescaler is implemented
as a 10-bit free-running counter with programmable reload at overflow. Writing a value to
the prescaler will cause the prescaler to restart.
10.3 Basic timer operation
The Timer is a free-running up/down counter counting at the pace determined by the
prescaler. The timer is started by setting the CCU Mode Select bits TMOD21 and
TMOD20 in the CCU Control Register 0 (TCR20) as shown in the table in the TCR20
register description (Table 47).
The CCU direction control bit, TDIR2, determines the direction of the count. TDIR2 = 0:
Count up, TDIR2 = 1: Count down. If the timer counting direction is changed while the
counter is running, the count sequence will be reversed in the CCUCLK cycle following the
write of TDIR2. The timer can be written or read at any time and newly-written values will
take effect when the prescaler overflows. The timer is accessible through two SFRs,
TL2(low byte) and TH2(high byte). A third 16-bit SFR, TOR2H:TOR2L, determines the
overflow reload value. TL2, TH2 and TOR2H, TOR2L will be 0 after a reset
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Up-counting: When the timer contents are FFFFH, the next CCUCLK cycle will set the
counter value to the contents of TOR2H:TOR2L.
Down-counting: When the timer contents are 0000H, the next CCUCLK cycle will set the
counter value to the contents of TOR2H:TOR2L. During the CCUCLK cycle when the
reload is performed, the CCU Timer Overflow Interrupt Flag (TOIF2) in the CCU Interrupt
Flag Register (TIFR2) will be set, and, if the EA bit in the IEN0 register and ECCU bit in
the IEN1 register (IEN1.4) are set, program execution will vector to the overflow interrupt.
The user has to clear the interrupt flag in software by writing a logic 0 to it.
When writing to the reload registers, TOR2H and TOR2L, the values written are stored in
two 8-bit shadow registers. In order to latch the contents of the shadow registers into
TOR2H and TOR2L, the user must write a logic 1 to the CCU Timer Compare/Overflow
Update bit TCOU2, in CCU Timer Control Register 1 (TCR21). The function of this bit
depends on whether the timer is running in PWM mode or in basic timer mode. In basic
timer mode, writing a one to TCOU2 will cause the values to be latched immediately and
the value of TCOU2 will always read as zero. In PWM mode, writing a one to TCOU2 will
cause the contents of the shadow registers to be updated on the next CCU Timer
overflow. As long as the latch is pending, TCOU2 will read as one and will return to zero
when the latching takes place. TCOU2 also controls the latching of the Output Compare
registers OCR2A, OCR2B and OCR2C.
When writing to timer high byte, TH2, the value written is stored in a shadow register.
When TL2 is written, the contents of TH2’s shadow register is transferred to TH2 at the
same time that TL2 gets updated. Thus, TH2 should be written prior to writing to TL2. If a
write to TL2 is followed by another write to TL2, without TH2 being written in between, the
value of TH2 will be transferred directly to the high byte of the timer.
If the 16-bit CCU Timer is to be used as an 8-bit timer, the user can write FFh (for
upcounting) or 00h (for downcounting) to TH2. When TL2 is written, FFh:TH2 (for
upcounting) and 00h (for downcounting) will be loaded to CCU Timer. The user will not
need to rewrite TH2 again for an 8-bit timer operation unless there is a change in count
direction
When reading the timer, TL2 must be read first. When TL2 is read, the contents of the
timer high byte are transferred to a shadow register in the same PCLK cycle as the read is
performed. When TH2 is read, the contents of the shadow register are read instead. If a
read from TL2 is followed by another read from TL2 without TH2 being read in between,
the high byte of the timer will be transferred directly to TH2.
Table 43:
CCU prescaler control register, high byte (TPCR2H - address CBh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
-
-
-
-
TPCR2H.1
TPCR2H.0
Reset
x
x
x
x
x
x
0
0
Table 44:
CCU prescaler control register, high byte (TPCR2H - address CBh) bit description
Bit Symbol
Description
0
TPCR2H.0
Prescaler bit 8
1
TPCR2H.1
Prescaler bit 9
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Table 45:
CCU prescaler control register, low byte (TPCR2L - address CAh) bit allocation
Bit
7
6
5
4
Symbol
TPCR2L.7
TPCR2L.6
TPCR2L.5
Reset
0
0
0
Table 46:
Table 47:
3
2
1
0
TPCR2L.4
TPCR2L.3
TPCR2L.2
TPCR2L.1
TPCR2L.0
0
0
0
0
0
CCU prescaler control register, low byte (TPCR2L - address CAh) bit description
Bit
Symbol
Description
0
TPCR2L.0
Prescaler bit 0
1
TPCR2L.1
Prescaler bit 1
2
TPCR2L.2
Prescaler bit 2
3
TPCR2L.3
Prescaler bit 3
4
TPCR2L.4
Prescaler bit 4
5
TPCR2L.5
Prescaler bit 5
6
TPCR2L.6
Prescaler bit 6
7
TPCR2L.7
Prescaler bit 7
CCU control register 0 (TCR20 - address C8h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
PLLEN
HLTRN
HLTEN
ALTCD
ALTAB
TDIR2
TMOD21
TMOD20
Reset
0
0
0
0
0
0
0
0
Table 48:
CCU control register 0 (TCR20 - address C8h) bit description
Bit Symbol
Description
1:2 TMOD20/21
CCU Timer mode (TMOD21, TMOD20):
00 — Timer is stopped
01 — Basic timer function
10 — Asymmetrical PWM (uses PLL as clock source)
11 — Symmetrical PWM (uses PLL as clock source)
2
TDIR2
Count direction of the CCU Timer. When logic 0, count up, When logic 1, count down.
3
ALTAB
PWM channel A/B alternately output enable. When this bit is set, the output of PWM channel A and B
are alternately gated on every counter cycle.
4
ALTCD
PWM channel C/D alternately output enable. When this bit is set, the output of PWM channel C and D
are alternately gated on every counter cycle.
5
HLTEN
PWM Halt Enable. When logic 1, a capture event as enabled for Input Capture A pin will immediately
stop all activity on the PWM pins and set them to a predetermined state.
6
HLTRN
PWM Halt. When set indicates a halt took place. In order to re-activate the PWM, the user must clear
the HLTRN bit.
7
PLLEN
Phase Locked Loop Enable. When set to logic 1, starts PLL operation. After the PLL is in lock this bit it
will read back a one.
10.4 Output compare
The four output compare channels A, B, C and D are controlled through four 16-bit SFRs,
OCRAH:OCRAL, OCRBH:OCRBL, OCRCH:OCRCL, OCRDH: OCRDL. Each output
compare channel needs to be enabled in order to operate. The channel is enabled by
selecting a Compare Output Action by setting the OCMx1:0 bits in the Capture Compare x
Control Register – CCCRx (x = A, B, C, D). When a compare channel is enabled, the user
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will have to set the associated I/O pin to the desired output mode to connect the pin.
(Note: The SFR bits for port pins P2.6, P1.6, P1.7, P2.1 must be set to logic 1 in order for
the compare channel outputs to be visible at the port pins.) When the contents of TH2:TL2
match that of OCRxH:OCRxL, the Timer Output Compare Interrupt Flag - TOCFx is set in
TIFR2. This happens in the CCUCLK cycle after the compare takes place. If EA and the
Timer Output Compare Interrupt Enable bit – TOCIE2x (in TICR2 register), as well as
ECCU bit in IEN1 are all set, the program counter will be vectored to the corresponding
interrupt. The user must manually clear the bit by writing a logic 0 to it.
Two bits in OCCRx, the Output Compare x Mode bits OCMx1 and OCMx0 select what
action is taken when a compare match occurs. Enabled compare actions take place even
if the interrupt is disabled.
In order for a Compare Output Action to occur, the compare values must be within the
counting range of the CCU timer.
When the compare channel is enabled, the I/O pin (which must be configured as an
output) will be connected to an internal latch controlled by the compare logic. The value of
this latch is zero from reset and can be changed by invoking a forced compare. A forced
compare is generated by writing a logic 1 to the Force Compare x Output bit – FCOx bit in
OCCRx. Writing a one to this bit generates a transition on the corresponding I/O pin as set
up by OCMx1/OCMx0 without causing an interrupt. In basic timer operating mode the
FCOx bits always read zero. (Note: This bit has a different function in PWM mode.) When
an output compare pin is enabled and connected to the compare latch, the state of the
compare pin remains unchanged until a compare event or forced compare occurs.
Table 49:
Capture compare control register (CCRx - address Exh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
ICECx2
ICECx1
ICECx0
ICESx
ICNFx
FCOx
OCMx1
OCMx0
Reset
0
0
0
0
0
0
0
0
Table 50:
Capture compare control register (CCRx - address Exh) bit description
Bit Symbol
Description
0
OCMx0
Output Compare x Mode. See Table 52 “Output compare pin behavior.”
1
OCMx1
2
FCOx
Force Compare X Output Bit. When set, invoke a force compare.
3
ICNFx
Input Capture x Noise Filter Enable Bit. When logic 1, the capture logic needs to see four consecutive
samples of the same value in order to recognize an edge as a capture event. The inputs are sampled
every two CCLK periods regardless of the speed of the timer.
4
ICESx
Input Capture x Edge Select Bit. When logic 0: Negative edge triggers a capture, When logic 1: Positive
edge triggers a capture.
5
ICECx0
Capture Delay Setting Bit 0. See Table 51 for details.
6
ICECx1
Capture Delay Setting Bit 1. See Table 51 for details.
7
ICECx2
Capture Delay Setting Bit 2. See Table 51 for details.
When the user writes to change the output compare value, the values written to OCRH2x
and OCRL2x are transferred to two 8-bit shadow registers. In order to latch the contents of
the shadow registers into the capture compare register, the user must write a logic 1 to the
CCU Timer Compare/Overflow Update bit TCOU2, in the CCU Control Register 1 TCR21. The function of this bit depends on whether the timer is running in PWM mode or
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in basic timer mode. In basic timer mode, writing a one to TCOU2 will cause the values to
be latched immediately and the value of TCOU2 will always read as zero. In PWM mode,
writing a one to TCOU2 will cause the contents of the shadow registers to be updated on
the next CCU Timer overflow. As long as the latch is pending, TCOU2 will read as one and
will return to zero when the latch takes place. TCOU2 also controls the latching of all the
Output Compare registers as well as the Timer Overflow Reload registers - TOR2.
10.5 Input capture
Input capture is always enabled. Each time a capture event occurs on one of the two input
capture pins, the contents of the timer is transferred to the corresponding 16-bit input
capture register ICRAH:ICRAL or ICRBH:ICRBL. The capture event is defined by the
Input Capture Edge Select – ICESx bit (x being A or B) in the CCCRx register. The user
will have to configure the associated I/O pin as an input in order for an external event to
trigger a capture.
A simple noise filter can be enabled on the input capture input. When the Input Capture
Noise Filter ICNFx bit is set, the capture logic needs to see four consecutive samples of
the same value in order to recognize an edge as a capture event. The inputs are sampled
every two CCLK periods regardless of the speed of the timer.
An event counter can be set to delay a capture by a number of capture events. The three
bits ICECx2, ICECx1 and ICECx0 in the CCCRx register determine the number of edges
the capture logic has to see before an input capture occurs.
When a capture event is detected, the Timer Input Capture x (x is A or B) Interrupt Flag –
TICF2x (TIFR2.1 or TIFR2.0) is set. If EA and the Timer Input Capture x Enable bit –
TICIE2x (TICR2.1 or TICR2.0) is set as well as the ECCU (IEN1.4) bit is set, the program
counter will be vectored to the corresponding interrupt. The interrupt flag must be cleared
manually by writing a logic 0 to it.
When reading the input capture register, ICRxL must be read first. When ICRxL is read,
the contents of the capture register high byte are transferred to a shadow register. When
ICRxH is read, the contents of the shadow register are read instead. (If a read from ICRxL
is followed by another read from ICRxL without ICRxH being read in between, the new
value of the capture register high byte (from the last ICRxL read) will be in the shadow
register).
Table 51:
Event delay counter for input capture
ICECx2
ICECx1
ICECx0
Delay (numbers of edges)
0
0
0
0
0
0
1
1
0
1
0
2
0
1
1
3
1
0
0
4
1
0
1
5
1
1
0
7
1
1
1
15
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10.6 PWM operation
PWM Operation has two main modes, asymmetrical and symmetrical. These modes of
timer operation are selected by writing 10H or 11H to TMOD21:TMOD20 as shown in
Section 10.3 “Basic timer operation”.
In asymmetrical PWM operation, the CCU Timer operates in downcounting mode
regardless of the setting of TDIR2. In this case, TDIR2 will always read 1.
In symmetrical mode, the timer counts up/down alternately and the value of TDIR2 has no
effect. The main difference from basic timer operation is the operation of the compare
module, which in PWM mode is used for PWM waveform generation. Table 52 shows the
behavior of the compare pins in PWM mode.
The user will have to configure the output compare pins as outputs in order to enable the
PWM output. As with basic timer operation, when the PWM (compare) pins are connected
to the compare logic, their logic state remains unchanged. However, since the bit FCO is
used to hold the halt value, only a compare event can change the state of the pin.
TOR2
compare value
timer value
0x0000
non-inverted
inverted
002aaa893
Fig 22. Asymmetrical PWM, downcounting.
TOR2
compare value
timer value
0
non-inverted
inverted
002aaa894
Fig 23. Symmetrical PWM.
The CCU Timer Overflow interrupt flag is set when the counter changes direction at the
top. For example, if TOR contains 01FFH, CCU Timer will count: …01FEH, 01FFH,
01FEH,… The flag is set in the counter cycle after the change from TOR to TOR-1.
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When the timer changes direction at the bottom, in this example, it counts …,0001H,
0000H, 0001H,… The CCU Timer overflow interrupt flag is set in the counter CCUCLK
cycle after the transition from 0001H to 0000H.
The status of the TDIR2 bit in TCR20 reflects the current counting direction. Writing to this
bit while operating in symmetrical mode has no effect.
10.7 Alternating output mode
In asymmetrical mode, the user can program PWM channels A/B and C/D as alternating
pairs for bridge drive control. By setting ALTAB or ALTCD bits in TCR20, the output of
these PWM channels are alternately gated on every counter cycle. This is shown in the
following figure:
TOR2
COMPARE VALUE A (or C)
COMPARE VALUE B (or D)
TIMER VALUE
0
PWM OUTPUT A (or C) (P2.6)
PWM OUTPUT B (or D) (P1.6)
002aaa895
Fig 24. Alternate output mode.
Table 52:
Output compare pin behavior.
OCMx1[1]
OCMx0[1] Output Compare pin behavior
Basic timer mode
Asymmetrical PWM
Symmetrical PWM
0
0
Output compare disabled. On power-on, this is the default state, and pins
are configured as inputs.
0
1
Set when compare in
operation. Cleared on
compare match.[2]
1
0
invalid configuration
1
1
Toggles on compare
match[2]
Non-Inverted PWM. Set
on compare match.
Cleared on CCU Timer
underflow.
Non-Inverted PWM.
Cleared on compare
match, upcounting. Set
on compare match,
downcounting.
Inverted PWM. Cleared
on compare match. Set
on CCU Timer
underflow.[2]
Inverted PWM. Set on
compare match,
upcounting. Cleared on
compare match,
downcounting.[2]
[1]
x = A, B, C, D
[2]
‘ON’ means in the CCUCLK cycle after the event takes place.
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10.8 Synchronized PWM register update
When the OCRx registers are written, a built in mechanism ensures that the value is not
updated in the middle of a PWM pulse. This could result in an odd-length pulse. When the
registers are written, the values are placed in two shadow registers, as is the case in basic
timer operation mode. Writing to TCOU2 will cause the contents of the shadow registers
to be updated on the next CCU Timer overflow. If OCRxH and/or OCRxL are read before
the value is updated, the most currently written value is read.
10.9 HALT
Setting the HLTEN bit in TCR20 enables the PWM Halt Function. When halt function is
enabled, a capture event as enabled for the Input Capture A pin will immediately stop all
activity on the PWM pins and set them to a predetermined state defined by FCOx bit. In
PWM Mode, the FCOx bits in the CCCRx register hold the value the pin is forced to during
halt. The value of the setting can be read back. The capture function and the interrupt will
still operate as normal even if it has this added functionality enabled. When the PWM unit
is halted, the timer will still run as normal. The HLTRN bit in TCR20 will be set to indicate
that a halt took place. In order to re-activate the PWM, the user must clear the HLTRN bit.
The user can force the PWM unit into halt by writing a logic 1 to HLTRN bit.
10.10 PLL operation
The PWM module features a Phase Locked Loop that can be used to generate a
CCUCLK frequency between 16 MHz and 32 MHz. At this frequency the PWM module
provides ultrasonic PWM frequency with 10-bit resolution provided that the crystal
frequency is 1 MHz or higher (The PWM resolution is programmable up to 16 bits by
writing to TOR2H:TOR2L). The PLL is fed an input signal of 0.5 MHz to 1 MHz and
generates an output signal of 32 times the input frequency. This signal is used to clock the
timer. The user will have to set a divider that scales PCLK by a factor of 1 to 16. This
divider is found in the SFR register TCR21. The PLL frequency can be expressed as
follows:
PLL frequency = PCLK / (N+1)
Where: N is the value of PLLDV3:0.
Since N ranges in 0 to 15, the CCLK frequency can be in the range of PCLK to PCLK⁄16.
Table 53:
CCU control register 1 (TCR21 - address F9h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
TCOU2
-
-
-
PLLDV.3
PLLDV.2
PLLDV.1
PLLDV.0
Reset
0
x
x
x
0
0
0
0
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Table 54:
CCU control register 1 (TCR21 - address F9h) bit description
Bit Symbol
Description
0:3 PLLDV.3:0
PLL frequency divider.
4:6 -
Reserved.
7
In basic timer mode, writing a logic 1 to TCOU2 will cause the values to be latched immediately and the
value of TCOU2 will always read as logic 0. In PWM mode, writing a logic 1 to TCOU2 will cause the
contents of the shadow registers to be updated on the next CCU Timer overflow. As long as the latch is
pending, TCOU2 will read as logic 1 and will return to logic 0 when the latching takes place. TCOU2 also
controls the latching of the Output Compare registers OCRAx, OCRBx and OCRCx.
TCOU2
Setting the PLLEN bit in TCR20 starts the PLL. When PLLEN is set, it will not read back a
one until the PLL is in lock. At this time, the PWM unit is ready to operate and the timer
can be enabled. The following start-up sequence is recommended:
1. Set up the PWM module without starting the timer.
2. Calculate the right division factor so that the PLL receives an input clock signal of
500 kHz to 1 MHz. Write this value to PLLDV.
3. Set PLLEN. Wait until the bit reads one
4. Start the timer by writing a value to bits TMOD21, TMOD20
When the timer runs from the PLL, the timer operates asynchronously to the rest of the
microcontroller. Some restrictions apply:
• The user is discouraged from writing or reading the timer in asynchronous mode. The
results may be unpredictable
• Interrupts and flags are asynchronous. There will be delay as the event may not
actually be recognized until some CCLK cycles later (for interrupts and reads)
10.11 CCU interrupt structure
There are seven independent sources of interrupts in the CCU: timer overflow, captured
input events on Input Capture blocks A/B, and compare match events on Output Compare
blocks A through D. One common interrupt vector is used for the CCU service routine and
interrupts can occur simultaneously in system usage. To resolve this situation, a priority
encode function of the seven interrupt bits in TIFR2 SFR is implemented (after each bit is
AND-ed with the corresponding interrupt enable bit in the TICR2 register). The order of
priority is fixed as follows, from highest to lowest:
•
•
•
•
•
•
•
TOIF2
TICF2A
TICF2B
TOCF2A
TOCF2B
TOCF2C
TOCF2D
An interrupt service routine for the CCU can be as follows:
1. Read the priority-encoded value from the TISE2 register to determine the interrupt
source to be handled.
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2. After the current (highest priority) event is serviced, write a logic 0 to the
corresponding interrupt flag bit in the TIFR2 register to clear the flag.
3. Read the TISE2 register. If the priority-encoded interrupt source is ‘000’, all CCU
interrupts are serviced and a return from interrupt can occur. Otherwise, return to step
2 for the next interrupt.
EA (IEN0.7)
ECCU (IEN1.4)
TOIE2 (TICR2.7)
TOIF2 (TIFR2.7)
TICIE2A (TICR2.0)
TICF2A (TIFR2.0)
TICIE2B (TICR2.1)
TICF2B (TIFR2.1)
TOCIE2A (TICR2.3)
TOCF2A (TIFR2.3)
interrupt to
CPU
other
interrupt
sources
TOCIE2B (TICR2.4)
TOCF2B (TIFR2.4)
TOCIE2C (TICR2.5)
TOCF2C (TIFR2.5)
TOCIE2D (TICR2.6)
TOCF2D (TIFR2.6)
ENCINT.0
PRIORITY
ENCODER
ENCINT.1
ENCINT.2
002aaa896
Fig 25. Capture/compare unit interrupts.
Table 55:
CCU interrupt status encode register (TISE2 - address DEh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
-
-
-
ENCINT.2
ENCINT.1
ENCINT.0
Reset
x
x
x
x
x
0
0
0
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Table 56:
CCU interrupt status encode register (TISE2 - address DEh) bit description
Bit Symbol
Description
2:0 ENCINT.2:0
CCU Interrupt Encode output. When multiple interrupts happen, more than one interrupt flag is set in
CCU Interrupt Flag Register (TIFR2). The encoder output can be read to determine which interrupt is
to be serviced. The user must write a logic 0 to clear the corresponding interrupt flag bit in the TIFR2
register after the corresponding interrupt has been serviced. Refer to Table 58 for TIFR2 description.
000 — No interrupt pending.
001 — Output Compare Event D interrupt (lowest priority)
010 — Output Compare Event C interrupt.
011 — Output Compare Event B interrupt.
100 — Output Compare Event A interrupt.
101 — Input Capture Event B interrupt.
110 — Input Capture Event A interrupt.
111 — CCU Timer Overflow interrupt (highest priority).
3:7 Table 57:
Reserved.
CCU interrupt flag register (TIFR2 - address E9h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
TOIF2
TOCF2D
TOCF2C
TOCF2B
TOCF2A
-
TICF2B
TICF2A
Reset
0
0
0
0
0
x
0
0
Table 58:
CCU interrupt flag register (TIFR2 - address E9h) bit description
Bit Symbol
Description
0
TICF2A
Input Capture Channel A Interrupt Flag Bit. Set by hardware when an input capture event is detected.
Cleared by software.
1
TICF2B
Input Capture Channel B Interrupt Flag Bit. Set by hardware when an input capture event is detected.
Cleared by software.
2
-
Reserved for future use. Should not be set to logic 1 by user program.
3
TOCF2A
Output Compare Channel A Interrupt Flag Bit. Set by hardware when the contents of TH2:TL2 match that
of OCRHA:OCRLA. Compare channel A must be enabled in order to generate this interrupt. If EA bit in
IEN0, ECCU bit in IEN1 and TOCIE2A bit are all set, the program counter will vectored to the
corresponding interrupt. Cleared by software.
4
TOCF2B
Output Compare Channel B Interrupt Flag Bit. Set by hardware when the contents of TH2:TL2 match that
of OCRHB:OCRLB. Compare channel B must be enabled in order to generate this interrupt. If EA bit in
IEN0, ECCU bit in IEN1 and TOCIE2B bit are set, the program counter will vectored to the corresponding
interrupt. Cleared by software.
5
TOCF2C
Output Compare Channel C Interrupt Flag Bit. Set by hardware when the contents of TH2:TL2 match that
of OCRHC:OCRLC. Compare channel C must be enabled in order to generate this interrupt. If EA bit in
IEN0, ECCU bit in IEN1 and TOCIE2C bit are all set, the program counter will vectored to the
corresponding interrupt. Cleared by software.
6
TOCF2D
Output Compare Channel D Interrupt Flag Bit. Set by hardware when the contents of TH2:TL2 match that
of OCRHD:OCRLD. Compare channel D must be enabled in order to generate this interrupt. If EA bit in
IEN0, ECCU bit in IEN1 and TOCIE2D bit are all set, the program counter will vectored to the
corresponding interrupt. Cleared by software.
7
TOIF2
CCU Timer Overflow Interrupt Flag bit. Set by hardware on CCU Timer overflow. Cleared by software.
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Table 59:
CCU interrupt control register (TICR2 - address C9h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
TOIE2
TOCIE2D
TOCIE2C
TOCIE2B
TOCIE2A
-
TICIE2B
TICIE2A
Reset
0
0
0
0
0
x
0
0
Table 60:
CCU interrupt control register (TICR2 - address C9h) bit description
Bit Symbol
Description
0
TICIE2A
Input Capture Channel A Interrupt Enable Bit. If EA bit and this bit all be set, when a capture event is
detected, the program counter will vectored to the corresponding interrupt.
1
TICIE2B
Input Capture Channel B Interrupt Enable Bit. If EA bit and this bit all be set, when a capture event is
detected, the program counter will vectored to the corresponding interrupt.
2
-
Reserved for future use. Should not be set to logic 1 by user program.
3
TOCIE2A
Output Compare Channel A Interrupt Enable Bit. If EA bit and this bit are set to 1, when compare channel
is enabled and the contents of TH2:TL2 match that of OCRHA:OCRLA, the program counter will vectored
to the corresponding interrupt.
4
TOCIE2B
Output Compare Channel B Interrupt Enable Bit. If EA bit and this bit are set to 1, when compare channel
B is enabled and the contents of TH2:TL2 match that of OCRHB:OCRLB, the program counter will
vectored to the corresponding interrupt.
5
TOCIE2C
Output Compare Channel C Interrupt Enable Bit. If EA bit and this bit are set to 1, when compare channel
C is enabled and the contents of TH2:TL2 match that of OCRHC:OCRLC, the program counter will
vectored to the corresponding interrupt.
6
TOCIE2D
Output Compare Channel D Interrupt Enable Bit. If EA bit and this bit are set to 1, when compare channel
D is enabled and the contents of TH2:TL2 match that of OCRHD:OCRLD, the program counter will
vectored to the corresponding interrupt.
7
TOIE2
CCU Timer Overflow Interrupt Enable bit.
11. UART
The P89LPC938 has an enhanced UART that is compatible with the conventional 80C51
UART except that Timer 2 overflow cannot be used as a baud rate source. The
P89LPC938 does include an independent Baud Rate Generator. The baud rate can be
selected from the oscillator (divided by a constant), Timer 1 overflow, or the independent
Baud Rate Generator. In addition to the baud rate generation, enhancements over the
standard 80C51 UART include Framing Error detection, break detect, automatic address
recognition, selectable double buffering and several interrupt options.
The UART can be operated in 4 modes, as described in the following sections.
11.1 Mode 0
Serial data enters and exits through RXD. TXD outputs the shift clock. 8 bits are
transmitted or received, LSB first. The baud rate is fixed at 1⁄16 of the CPU clock frequency.
11.2 Mode 1
10 bits are transmitted (through TXD) or received (through RXD): a start bit (logic 0), 8
data bits (LSB first), and a stop bit (logic 1). When data is received, the stop bit is stored in
RB8 in Special Function Register SCON. The baud rate is variable and is determined by
the Timer 1 overflow rate or the Baud Rate Generator (see Section 11.6 “Baud Rate
generator and selection” on page 66).
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11.3 Mode 2
11 bits are transmitted (through TXD) or received (through RXD): start bit (logic 0), 8 data
bits (LSB first), a programmable 9th data bit, and a stop bit (logic 1). When data is
transmitted, the 9th data bit (TB8 in SCON) can be assigned the value of 0 or 1. Or, for
example, the parity bit (P, in the PSW) could be moved into TB8. When data is received,
the 9th data bit goes into RB8 in Special Function Register SCON and the stop bit is not
saved. The baud rate is programmable to either 1⁄16 or 1⁄32 of the CCLK frequency, as
determined by the SMOD1 bit in PCON.
11.4 Mode 3
11 bits are transmitted (through TXD) or received (through RXD): a start bit (logic 0), 8
data bits (LSB first), a programmable 9th data bit, and a stop bit (logic 1). Mode 3 is the
same as Mode 2 in all respects except baud rate. The baud rate in Mode 3 is variable and
is determined by the Timer 1 overflow rate or the Baud Rate Generator (see Section 11.6
“Baud Rate generator and selection” on page 66).
In all four modes, transmission is initiated by any instruction that uses SBUF as a
destination register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1.
Reception is initiated in the other modes by the incoming start bit if REN = 1.
11.5 SFR space
The UART SFRs are at the following locations:
Table 61:
UART SFR addresses
Register
Description
SFR location
PCON
Power Control
87H
SCON
Serial Port (UART) Control
98H
SBUF
Serial Port (UART) Data Buffer
99H
SADDR
Serial Port (UART) Address
A9H
SADEN
Serial Port (UART) Address Enable
B9H
SSTAT
Serial Port (UART) Status
BAH
BRGR1
Baud Rate Generator Rate High Byte
BFH
BRGR0
Baud Rate Generator Rate Low Byte
BEH
BRGCON
Baud Rate Generator Control
BDH
11.6 Baud Rate generator and selection
The P89LPC938 enhanced UART has an independent Baud Rate Generator. The baud
rate is determined by a value programmed into the BRGR1 and BRGR0 SFRs. The UART
can use either Timer 1 or the baud rate generator output as determined by BRGCON[2:1]
(see Figure 26). Note that Timer T1 is further divided by 2 if the SMOD1 bit (PCON.7) is
set. The independent Baud Rate Generator uses CCLK.
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11.7 Updating the BRGR1 and BRGR0 SFRs
The baud rate SFRs, BRGR1 and BRGR0 must only be loaded when the Baud Rate
Generator is disabled (the BRGEN bit in the BRGCON register is logic 0). This avoids the
loading of an interim value to the baud rate generator. (CAUTION: If either BRGR0 or
BRGR1 is written when BRGEN = 1, the result is unpredictable.)
Table 62:
UART baud rate generation
SCON.7
(SM0)
SCON.6
(SM1)
PCON.7
(SMOD1)
BRGCON.1
(SBRGS)
Receive/transmit baud rate for UART
0
0
X
X
CCLK⁄
16
0
1
0
0
CCLK⁄
(256−TH1)64
1
0
CCLK⁄
(256−TH1)32
((BRGR1, BRGR0)+16)
1
0
1
1
Table 63:
X
1
CCLK⁄
0
X
CCLK⁄
32
1
X
CCLK⁄
16
0
0
CCLK⁄
(256−TH1)64
1
0
CCLK⁄
(256−TH1)32
X
1
CCLK⁄
((BRGR1, BRGR0)+16)
Baud Rate Generator Control register (BRGCON - address BDh) bit allocation
Bit
7
6
5
4
3
2
1
Symbol
--
-
-
-
-
-
SBRGS
BRGEN
Reset
x
x
x
x
x
x
0
0
Table 64:
0
Baud Rate Generator Control register (BRGCON - address BDh) bit description
Bit Symbol
Description
0
BRGEN
Baud Rate Generator Enable. Enables the baud rate generator. BRGR1 and
BRGR0 can only be written when BRGEN = 0.
1
SBRGS
Select Baud Rate Generator as the source for baud rates to UART in modes 1 and
3 (see Table 62 for details)
2:7 -
reserved
timer 1 overflow
(PCLK-based)
SMOD1 = 1
SBRGS = 0
÷2
baud rate modes 1 and 3
SMOD1 = 0
baud rate generator
(CCLK-based)
SBRGS = 1
002aaa897
Fig 26. Baud rate generation for UART (Modes 1, 3).
11.8 Framing error
A Framing error occurs when the stop bit is sensed as a logic 0. A Framing error is
reported in the status register (SSTAT). In addition, if SMOD0 (PCON.6) is 1, framing
errors can be made available in SCON.7. If SMOD0 is 0, SCON.7 is SM0. It is
recommended that SM0 and SM1 (SCON[7:6]) are programmed when SMOD0 is logic 0.
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11.9 Break detect
A break detect is reported in the status register (SSTAT). A break is detected when any 11
consecutive bits are sensed low. Since a break condition also satisfies the requirements
for a framing error, a break condition will also result in reporting a framing error. Once a
break condition has been detected, the UART will go into an idle state and remain in this
idle state until a stop bit has been received. The break detect can be used to reset the
device and force the device into ISP mode by setting the EBRR bit (AUXR1.6)
Table 65:
Serial Port Control register (SCON - address 98h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
Reset
x
x
x
x
x
x
0
0
Table 66:
Serial Port Control register (SCON - address 98h) bit description
Bit Symbol
Description
0
RI
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or
approximately halfway through the stop bit time in Mode 1. For Mode 2 or Mode 3,
if SMOD0, it is set near the middle of the 9th data bit (bit 8). If SMOD0 = 1, it is set
near the middle of the stop bit (see SM2 - SCON.5 - for exceptions). Must be
cleared by software.
1
TI
Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or
at the stop bit (see description of INTLO bit in SSTAT register) in the other modes.
Must be cleared by software.
2
RB8
The 9th data bit that was received in Modes 2 and 3. In Mode 1 (SM2 must be 0),
RB8 is the stop bit that was received. In Mode 0, RB8 is undefined.
3
TB8
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software
as desired.
4
REN
Enables serial reception. Set by software to enable reception. Clear by software to
disable reception.
5
SM2
Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or
3, if SM2 is set to 1, then Rl will not be activated if the received 9th data bit (RB8)
is 0. In Mode 0, SM2 should be 0. In Mode 1, SM2 must be 0.
6
SM1
With SM0 defines the serial port mode, see Table 67.
7
SM0/FE
The use of this bit is determined by SMOD0 in the PCON register. If SMOD0 = 0,
this bit is read and written as SM0, which with SM1, defines the serial port mode. If
SMOD0 = 1, this bit is read and written as FE (Framing Error). FE is set by the
receiver when an invalid stop bit is detected. Once set, this bit cannot be cleared
by valid frames but is cleared by software. (Note: UART mode bits SM0 and SM1
should be programmed when SMOD0 is logic 0 - default mode on any reset.)
Table 67:
Serial Port modes
SM0, SM1
UART mode
UART baud rate
00
Mode 0: shift register
CCLK⁄
01
Mode 1: 8-bit UART
Variable (see Table 62)
10
Mode 2: 9-bit UART
CCLK⁄
11
Mode 3: 9-bit UART
Variable (see Table 62)
16
32
(default mode on any reset)
or CCLK⁄16
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Table 68:
Bit
Serial Port Status register (SSTAT - address BAh) bit allocation
7
6
5
Symbol
DBMOD
INTLO
CIDIS
DBISEL
FE
BR
OE
STINT
Reset
x
x
x
x
x
x
0
0
Table 69:
4
3
2
1
0
Serial Port Status register (SSTAT - address BAh) bit description
Bit Symbol
Description
0
STINT
Status Interrupt Enable. When set = 1, FE, BR, or OE can cause an interrupt. The
interrupt used (vector address 0023h) is shared with RI (CIDIS = 1) or the
combined TI/RI (CIDIS = 0). When cleared = 0, FE, BR, OE cannot cause an
interrupt. (Note: FE, BR, or OE is often accompanied by a RI, which will generate
an interrupt regardless of the state of STINT). Note that BR can cause a break
detect reset if EBRR (AUXR1.6) is set to logic 1.
1
OE
Overrun Error flag is set if a new character is received in the receiver buffer while it
is still full (before the software has read the previous character from the buffer), i.e.,
when bit 8 of a new byte is received while RI in SCON is still set. Cleared by
software.
2
BR
Break Detect flag. A break is detected when any 11 consecutive bits are sensed
low. Cleared by software.
3
FE
Framing error flag is set when the receiver fails to see a valid STOP bit at the end
of the frame. Cleared by software.
4
DBISEL
Double buffering transmit interrupt select. Used only if double buffering is enabled.
This bit controls the number of interrupts that can occur when double buffering is
enabled. When set, one transmit interrupt is generated after each character written
to SBUF, and there is also one more transmit interrupt generated at the beginning
(INTLO = 0) or the end (INTLO = 1) of the STOP bit of the last character sent (i.e.,
no more data in buffer). This last interrupt can be used to indicate that all transmit
operations are over. When cleared = 0, only one transmit interrupt is generated per
character written to SBUF. Must be logic 0 when double buffering is disabled. Note
that except for the first character written (when buffer is empty), the location of the
transmit interrupt is determined by INTLO. When the first character is written, the
transmit interrupt is generated immediately after SBUF is written.
5
CIDIS
Combined Interrupt Disable. When set = 1, Rx and Tx interrupts are separate.
When cleared = 0, the UART uses a combined Tx/Rx interrupt (like a conventional
80C51 UART). This bit is reset to logic 0 to select combined interrupts.
6
INTLO
Transmit interrupt position. When cleared = 0, the Tx interrupt is issued at the
beginning of the stop bit. When set = 1, the Tx interrupt is issued at end of the stop
bit. Must be logic 0 for mode 0. Note that in the case of single buffering, if the Tx
interrupt occurs at the end of a STOP bit, a gap may exist before the next start bit.
7
DBMOD Double buffering mode. When set = 1 enables double buffering. Must be logic 0 for
UART mode 0. In order to be compatible with existing 80C51 devices, this bit is
reset to logic 0 to disable double buffering.
11.10 More about UART Mode 0
In Mode 0, a write to SBUF will initiate a transmission. At the end of the transmission, TI
(SCON.1) is set, which must be cleared in software. Double buffering must be disabled in
this mode.
Reception is initiated by clearing RI (SCON.0). Synchronous serial transfer occurs and RI
will be set again at the end of the transfer. When RI is cleared, the reception of the next
character will begin. Refer to Figure 27
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S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16 S1 ... S16
write to
SBUF
transmit
shift
RXD (data out)
D0
D1
D2
D3
D4
D5
D6
D7
TXD (shift clock)
TI
WRITE to SCON
(clear RI)
RI
receive
shift
RXD
(data in)
TXD (shift clock)
D0
D1
D2
D3
D4
D5
D6
D7
002aaa925
Fig 27. Serial Port Mode 0 (double buffering must be disabled).
11.11 More about UART Mode 1
Reception is initiated by detecting a 1-to-0 transition on RXD. RXD is sampled at a rate 16
times the programmed baud rate. When a transition is detected, the divide-by-16 counter
is immediately reset. Each bit time is thus divided into 16 counter states. At the 7th, 8th,
and 9th counter states, the bit detector samples the value of RXD. The value accepted is
the value that was seen in at least 2 of the 3 samples. This is done for noise rejection. If
the value accepted during the first bit time is not 0, the receive circuits are reset and the
receiver goes back to looking for another 1-to-0 transition. This provides rejection of false
start bits. If the start bit proves valid, it is shifted into the input shift register, and reception
of the rest of the frame will proceed.
The signal to load SBUF and RB8, and to set RI, will be generated if, and only if, the
following conditions are met at the time the final shift pulse is generated: RI = 0 and either
SM2 = 0 or the received stop bit = 1. If either of these two conditions is not met, the
received frame is lost. If both conditions are met, the stop bit goes into RB8, the 8 data
bits go into SBUF, and RI is activated.
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TX clock
write to
SBUF
shift
transmit
start
bit
TXD
D0
D1
D2
D3
D4
D5
D6
D7
stop bit
TI
INTLO = 0
RX
clock
RXD
÷16 reset
start
bit
D0
D1
D2
D3
D4
D5
D6
D7
INTLO = 1
stop bit
receive
shift
RI
002aaa926
Fig 28. Serial Port Mode 1 (only single transmit buffering case is shown).
11.12 More about UART Modes 2 and 3
Reception is the same as in Mode 1.
The signal to load SBUF and RB8, and to set RI, will be generated if, and only if, the
following conditions are met at the time the final shift pulse is generated. (a) RI = 0, and
(b) Either SM2 = 0, or the received 9th data bit = 1. If either of these conditions is not met,
the received frame is lost, and RI is not set. If both conditions are met, the received 9th
data bit goes into RB8, and the first 8 data bits go into SBUF.
TX clock
write to
SBUF
transmit
shift
start
bit
TXD
D0
D1
D2
D3
D4
D5
D6
D7
TB8
stop bit
TI
INTLO = 0
RX
clock
RXD
÷16 reset
start
bit
D0
D1
D2
D3
D4
D5
D6
D7
RB8
INTLO = 1
stop bit
receive
shift
RI
SMOD0 = 0
SMOD0 = 1
002aaa927
Fig 29. Serial Port Mode 2 or 3 (only single transmit buffering case is shown).
11.13 Framing error and RI in Modes 2 and 3 with SM2 = 1
If SM2 = 1 in modes 2 and 3, RI and FE behaves as in the following table.
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Table 70:
FE and RI when SM2 = 1 in Modes 2 and 3
Mode
PCON.6
(SMOD0)
RB8
RI
FE
2
0
0
No RI when RB8 = 0
Occurs during STOP
bit
1
Similar to Figure 29, with SMOD0 = 0, RI
occurs during RB8, one bit before FE
Occurs during STOP
bit
0
No RI when RB8 = 0
Will NOT occur
3
1
1
[29],
with SMOD0 = 1, RI occurs
Similar to
during STOP bit
Occurs during STOP
bit
11.14 Break detect
A break is detected when 11 consecutive bits are sensed low and is reported in the status
register (SSTAT). For Mode 1, this consists of the start bit, 8 data bits, and two stop bit
times. For Modes 2 and 3, this consists of the start bit, 9 data bits, and one stop bit. The
break detect bit is cleared in software or by a reset. The break detect can be used to reset
the device and force the device into ISP mode. This occurs if the UART is enabled and the
the EBRR bit (AUXR1.6) is set and a break occurs.
11.15 Double buffering
The UART has a transmit double buffer that allows buffering of the next character to be
written to SBUF while the first character is being transmitted. Double buffering allows
transmission of a string of characters with only one stop bit between any two characters,
provided the next character is written between the start bit and the stop bit of the previous
character.
Double buffering can be disabled. If disabled (DBMOD, i.e. SSTAT.7 = 0), the UART is
compatible with the conventional 80C51 UART. If enabled, the UART allows writing to
SnBUF while the previous data is being shifted out.
11.16 Double buffering in different modes
Double buffering is only allowed in Modes 1, 2 and 3. When operated in Mode 0, double
buffering must be disabled (DBMOD = 0).
11.17 Transmit interrupts with double buffering enabled (Modes 1, 2, and 3)
Unlike the conventional UART, when double buffering is enabled, the Tx interrupt is
generated when the double buffer is ready to receive new data. The following occurs
during a transmission (assuming eight data bits):
1. The double buffer is empty initially.
2. The CPU writes to SBUF.
3. The SBUF data is loaded to the shift register and a Tx interrupt is generated
immediately.
4. If there is more data, go to 6, else continue.
5. If there is no more data, then:
– If DBISEL is logic 0, no more interrupts will occur.
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– If DBISEL is logic 1 and INTLO is logic 0, a Tx interrupt will occur at the beginning
of the STOP bit of the data currently in the shifter (which is also the last data).
– If DBISEL is logic 1 and INTLO is logic 1, a Tx interrupt will occur at the end of the
STOP bit of the data currently in the shifter (which is also the last data).
– Note that if DBISEL is logic 1 and the CPU is writing to SBUF when the STOP bit of
the last data is shifted out, there can be an uncertainty of whether a Tx interrupt is
generated already with the UART not knowing whether there is any more data
following.
6. If there is more data, the CPU writes to SBUF again. Then:
– If INTLO is logic 0, the new data will be loaded and a Tx interrupt will occur at the
beginning of the STOP bit of the data currently in the shifter.
– If INTLO is logic 1, the new data will be loaded and a Tx interrupt will occur at the
end of the STOP bit of the data currently in the shifter.
– Go to 3.
TXD
write to
SBUF
TX interrupt
single buffering (DBMOD/SSTAT.7 = 0), early interrupt (INTLO/SSTAT.6 = 0) is shown
TXD
write to
SBUF
TX interrupt
double buffering (DBMOD/SSTAT.7 = 1), early interrupt (INTLO/SSTAT.6 = 0) is shown,
no ending TX interrupt (DBISEL/SSTAT.4 = 0)
TXD
write to
SBUF
TX interrupt
double buffering (DBMOD/SSTAT.7 = 1), early interrupt (INTLO/SSTAT.6 = 0) is shown,
with ending TX interrupt (DBISEL/SSTAT.4 = 1)
002aaa928
Fig 30. Transmission with and without double buffering.
11.18 The 9th bit (bit 8) in double buffering (Modes 1, 2, and 3)
If double buffering is disabled (DBMOD, i.e. SSTAT.7 = 0), TB8 can be written before or
after SBUF is written, provided TB8 is updated before that TB8 is shifted out. TB8 must
not be changed again until after TB8 shifting has been completed, as indicated by the Tx
interrupt.
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If double buffering is enabled, TB8 MUST be updated before SBUF is written, as TB8 will
be double-buffered together with SBUF data. The operation described in the Section
11.17 “Transmit interrupts with double buffering enabled (Modes 1, 2, and 3)” on page 72
becomes as follows:
1. The double buffer is empty initially.
2. The CPU writes to TB8.
3. The CPU writes to SBUF.
4. The SBUF/TB8 data is loaded to the shift register and a Tx interrupt is generated
immediately.
5. If there is more data, go to 7, else continue on 6.
6. If there is no more data, then:
– If DBISEL is logic 0, no more interrupt will occur.
– If DBISEL is logic 1 and INTLO is logic 0, a Tx interrupt will occur at the beginning
of the STOP bit of the data currently in the shifter (which is also the last data).
– If DBISEL is logic 1 and INTLO is logic 1, a Tx interrupt will occur at the end of the
STOP bit of the data currently in the shifter (which is also the last data).
7. If there is more data, the CPU writes to TB8 again.
8. The CPU writes to SBUF again. Then:
– If INTLO is logic 0, the new data will be loaded and a Tx interrupt will occur at the
beginning of the STOP bit of the data currently in the shifter.
– If INTLO is logic 1, the new data will be loaded and a Tx interrupt will occur at the
end of the STOP bit of the data currently in the shifter.
9. Go to 4.
10.Note that if DBISEL is logic 1 and the CPU is writing to SBUF when the STOP bit of
the last data is shifted out, there can be an uncertainty of whether a Tx interrupt is
generated already with the UART not knowing whether there is any more data
following.
11.19 Multiprocessor communications
UART modes 2 and 3 have a special provision for multiprocessor communications. In
these modes, 9 data bits are received or transmitted. When data is received, the 9th bit is
stored in RB8. The UART can be programmed such that when the stop bit is received, the
serial port interrupt will be activated only if RB8 = 1. This feature is enabled by setting bit
SM2 in SCON. One way to use this feature in multiprocessor systems is as follows:
When the master processor wants to transmit a block of data to one of several slaves, it
first sends out an address byte which identifies the target slave. An address byte differs
from a data byte in that the 9th bit is 1 in an address byte and 0 in a data byte. With
SM2 = 1, no slave will be interrupted by a data byte. An address byte, however, will
interrupt all slaves, so that each slave can examine the received byte and see if it is being
addressed. The addressed slave will clear its SM2 bit and prepare to receive the data
bytes that follow. The slaves that weren’t being addressed leave their SM2 bits set and go
on about their business, ignoring the subsequent data bytes.
Note that SM2 has no effect in Mode 0, and must be logic 0 in Mode 1.
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11.20 Automatic address recognition
Automatic address recognition is a feature which allows the UART to recognize certain
addresses in the serial bit stream by using hardware to make the comparisons. This
feature saves a great deal of software overhead by eliminating the need for the software to
examine every serial address which passes by the serial port. This feature is enabled by
setting the SM2 bit in SCON. In the 9 bit UART modes (mode 2 and mode 3), the Receive
Interrupt flag (RI) will be automatically set when the received byte contains either the
‘Given’ address or the ‘Broadcast’ address. The 9 bit mode requires that the 9th
information bit is a 1 to indicate that the received information is an address and not data.
Using the Automatic Address Recognition feature allows a master to selectively
communicate with one or more slaves by invoking the Given slave address or addresses.
All of the slaves may be contacted by using the Broadcast address. Two special Function
Registers are used to define the slave’s address, SADDR, and the address mask,
SADEN. SADEN is used to define which bits in the SADDR are to be used and which bits
are ‘don’t care’. The SADEN mask can be logically ANDed with the SADDR to create the
‘Given’ address which the master will use for addressing each of the slaves. Use of the
Given address allows multiple slaves to be recognized while excluding others. The
following examples will help to show the versatility of this scheme:
Table 71:
Slave 0/1 examples
Example 1
Slave 0
Example 2
SADDR
= 1100 0000
SADEN
Given
Slave 1
SADDR
= 1100 0000
= 1111 1101
SADEN
= 1111 1110
= 1100 00X0
Given
= 1100 000X
In the above example SADDR is the same and the SADEN data is used to differentiate
between the two slaves. Slave 0 requires a 0 in bit 0 and it ignores bit 1. Slave 1 requires
a 0 in bit 1 and bit 0 is ignored. A unique address for Slave 0 would be 1100 0010 since
slave 1 requires a 0 in bit 1. A unique address for slave 1 would be 1100 0001 since a 1 in
bit 0 will exclude slave 0. Both slaves can be selected at the same time by an address
which has bit 0 = 0 (for slave 0) and bit 1 = 0 (for slave 1). Thus, both could be addressed
with 1100 0000.
In a more complex system the following could be used to select slaves 1 and 2 while
excluding slave 0:
Table 72:
Slave 0/1/2 examples
Example 1
Example 2
Example 3
Slave 0 SADDR = 1100 0000
Slave 1 SADDR = 1110 0000
Slave 2
SADEN = 1111 1001
Given
= 1100
0XX0
SADDR
= 1100 0000
SADEN = 1111 1010
SADEN
= 1111 1100
Given
Given
= 1110 00XX
= 1110 0X0X
In the above example the differentiation among the 3 slaves is in the lower 3 address bits.
Slave 0 requires that bit 0 = 0 and it can be uniquely addressed by 1110 0110. Slave 1
requires that bit 1 = 0 and it can be uniquely addressed by 1110 and 0101. Slave 2
requires that bit 2 = 0 and its unique address is 1110 0011. To select Slaves 0 and 1 and
exclude Slave 2 use address 1110 0100, since it is necessary to make bit 2 = 1 to exclude
slave 2. The Broadcast Address for each slave is created by taking the logical OR of
SADDR and SADEN. Zeros in this result are treated as don’t-cares. In most cases,
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interpreting the don’t-cares as ones, the broadcast address will be FF hexadecimal. Upon
reset SADDR and SADEN are loaded with 0s. This produces a given address of all ‘don’t
cares’ as well as a Broadcast address of all ‘don’t cares’. This effectively disables the
Automatic Addressing mode and allows the microcontroller to use standard UART drivers
which do not make use of this feature.
12. I2C interface
The I2C-bus uses two wires, serial clock (SCL) and serial data (SDA) to transfer
information between devices connected to the bus, and has the following features:
• Bidirectional data transfer between masters and slaves
• Multimaster bus (no central master)
• Arbitration between simultaneously transmitting masters without corruption of serial
data on the bus
• Serial clock synchronization allows devices with different bit rates to communicate via
one serial bus
• Serial clock synchronization can be used as a handshake mechanism to suspend and
resume serial transfer
• The I2C-bus may be used for test and diagnostic purposes
A typical I2C-bus configuration is shown in Figure 31. Depending on the state of the
direction bit (R/W), two types of data transfers are possible on the I2C-bus:
• Data transfer from a master transmitter to a slave receiver. The first byte transmitted
by the master is the slave address. Next follows a number of data bytes. The slave
returns an acknowledge bit after each received byte.
• Data transfer from a slave transmitter to a master receiver. The first byte (the slave
address) is transmitted by the master. The slave then returns an acknowledge bit.
Next follows the data bytes transmitted by the slave to the master. The master returns
an acknowledge bit after all received bytes other than the last byte. At the end of the
last received byte, a ‘not acknowledge’ is returned. The master device generates all of
the serial clock pulses and the START and STOP conditions. A transfer is ended with
a STOP condition or with a repeated START condition. Since a repeated START
condition is also the beginning of the next serial transfer, the I2C-bus will not be
released.
The P89LPC938 device provides a byte-oriented I2C interface. It has four operation
modes: Master Transmitter Mode, Master Receiver Mode, Slave Transmitter Mode and
Slave Receiver Mode
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RP
RP
SDA
I2C-bus
SCL
P1.3/SDA
OTHER DEVICE
WITH I2C-BUS
INTERFACE
P1.2/SCL
P89LPC932A1
OTHER DEVICE
WITH I2C-BUS
INTERFACE
002aaa898
Fig 31. I2C-bus configuration.
The P89LPC938 CPU interfaces with the I2C-bus through six Special Function Registers
(SFRs): I2CON (I2C Control Register), I2DAT (I2C Data Register), I2STAT (I2C Status
Register), I2ADR (I2C Slave Address Register), I2SCLH (SCL Duty Cycle Register High
Byte), and I2SCLL (SCL Duty Cycle Register Low Byte).
12.1 I2C data register
I2DAT register contains the data to be transmitted or the data received. The CPU can read
and write to this 8-bit register while it is not in the process of shifting a byte. Thus this
register should only be accessed when the SI bit is set. Data in I2DAT remains stable as
long as the SI bit is set. Data in I2DAT is always shifted from right to left: the first bit to be
transmitted is the MSB (bit 7), and after a byte has been received, the first bit of received
data is located at the MSB of I2DAT.
Table 73:
12.2
I2C data register (I2DAT - address DAh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
I2DAT.7
I2DAT.6
I2DAT.5
I2DAT.4
I2DAT.3
I2DAT.2
I2DAT.1
I2DAT.0
Reset
0
0
0
0
0
0
0
0
I2C slave address register
I2ADR register is readable and writable, and is only used when the I2C interface is set to
slave mode. In master mode, this register has no effect. The LSB of I2ADR is general call
bit. When this bit is set, the general call address (00h) is recognized.
Table 74:
I2C slave address register (I2ADR - address DBh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
I2ADR.6
I2ADR.5
I2ADR.4
I2ADR.3
I2ADR.2
I2ADR.1
I2ADR.0
GC
Reset
0
0
0
0
0
0
0
0
Table 75:
I2C slave address register (I2ADR - address DBh) bit description
Bit Symbol
Description
0
General call bit. When set, the general call address (00H) is recognized,
otherwise it is ignored.
GC
1:7 I2ADR1:7 7 bit own slave address. When in master mode, the contents of this register has
no effect.
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12.3 I2C control register
The CPU can read and write this register. There are two bits are affected by hardware: the
SI bit and the STO bit. The SI bit is set by hardware and the STO bit is cleared by
hardware.
CRSEL determines the SCL source when the I2C-bus is in master mode. In slave mode
this bit is ignored and the bus will automatically synchronize with any clock frequency up
to 400 kHz from the master I2C device. When CRSEL = 1, the I2C interface uses the
Timer 1 overflow rate divided by 2 for the I2C clock rate. Timer 1 should be programmed
by the user in 8 bit auto-reload mode (Mode 2).
Data rate of I2C-bus = Timer overflow rate / 2 = PCLK / (2*(256-reload value)).
If fosc = 12 MHz, reload value is 0 to 255, so I2C data rate range is 11.72 Kbit/sec to
3000 Kbit/sec.
When CRSEL = 0, the I2C interface uses the internal clock generator based on the value
of I2SCLL and I2CSCLH register. The duty cycle does not need to be 50 %.
The STA bit is START flag. Setting this bit causes the I2C interface to enter master mode
and attempt transmitting a START condition or transmitting a repeated START condition
when it is already in master mode.
The STO bit is STOP flag. Setting this bit causes the I2C interface to transmit a STOP
condition in master mode, or recovering from an error condition in slave mode.
If the STA and STO are both set, then a STOP condition is transmitted to the I2C-bus if it is
in master mode, and transmits a START condition afterwards. If it is in slave mode, an
internal STOP condition will be generated, but it is not transmitted to the bus.
I2C Control register (I2CON - address D8h) bit allocation
Table 76:
Bit
7
6
Symbol
-
I2EN
STA
STO
SI
AA
-
CRSEL
Reset
x
0
0
0
0
0
x
0
Table 77:
5
4
3
2
1
0
I2C Control register (I2CON - address D8h) bit description
Bit Symbol
Description
0
CRSEL
SCL clock selection. When set = 1, Timer 1 overflow generates SCL, when cleared
= 0, the internal SCL generator is used base on values of I2SCLH and I2SCLL.
1
-
reserved
2
AA
The Assert Acknowledge Flag. When set to 1, an acknowledge (low level to SDA)
will be returned during the acknowledge clock pulse on the SCL line on the
following situations:
(1)The ‘own slave address’ has been received. (2)The general call address has
been received while the general call bit (GC) in I2ADR is set. (3) A data byte has
been received while the I2C interface is in the Master Receiver Mode. (4)A data
byte has been received while the I2C interface is in the addressed Slave Receiver
Mode. When cleared to 0, an not acknowledge (high level to SDA) will be returned
during the acknowledge clock pulse on the SCL line on the following situations: (1)
A data byte has been received while the I2C interface is in the Master Receiver
Mode. (2) A data byte has been received while the I2C interface is in the addressed
Slave Receiver Mode.
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Table 77:
I2C Control register (I2CON - address D8h) bit description …continued
Bit Symbol
Description
3
SI
I2C Interrupt Flag. This bit is set when one of the 25 possible I2C states is entered.
When EA bit and EI2C (IEN1.0) bit are both set, an interrupt is requested when SI
is set. Must be cleared by software by writing 0 to this bit.
4
STO
STOP Flag. STO = 1: In master mode, a STOP condition is transmitted to the
I2C-bus. When the bus detects the STOP condition, it will clear STO bit
automatically. In slave mode, setting this bit can recover from an error condition. In
this case, no STOP condition is transmitted to the bus. The hardware behaves as if
a STOP condition has been received and it switches to ‘not addressed’ Slave
Receiver Mode. The STO flag is cleared by hardware automatically.
5
STA
Start Flag. STA = 1: I2C-bus enters master mode, checks the bus and generates a
START condition if the bus is free. If the bus is not free, it waits for a STOP
condition (which will free the bus) and generates a START condition after a delay
of a half clock period of the internal clock generator. When the I2C interface is
already in master mode and some data is transmitted or received, it transmits a
repeated START condition. STA may be set at any time, it may also be set when
the I2C interface is in an addressed slave mode. STA = 0: no START condition or
repeated START condition will be generated.
6
I2EN
I2C Interface Enable. When set, enables the I2C interface. When clear, the I2C
function is disabled.
7
-
reserved
12.4 I2C Status register
This is a read-only register. It contains the status code of the I2C interface. The least three
bits are always 0. There are 26 possible status codes. When the code is F8H, there is no
relevant information available and SI bit is not set. All other 25 status codes correspond to
defined I2C states. When any of these states entered, the SI bit will be set. Refer to
Table 83 to Table 86 for details.
Table 78:
Bit
I2C Status register (I2STAT - address D9h) bit allocation
7
6
5
4
3
2
1
0
Symbol
STA.4
STA.3
STA.2
STA.1
STA.0
0
0
0
Reset
0
0
0
0
0
0
0
0
Table 79:
I2C Status register (I2STAT - address D9h) bit description
Bit Symbol
Description
0:2 -
Reserved, are always set to 0.
3:7 STA[0:4] I2C Status code.
12.5 I2C SCL duty cycle registers I2SCLH and I2SCLL
When the internal SCL generator is selected for the I2C interface by setting CRSEL = 0 in
the I2CON register, the user must set values for registers I2SCLL and I2SCLH to select
the data rate. I2SCLH defines the number of PCLK cycles for SCL = high, I2SCLL defines
the number of PCLK cycles for SCL = low. The frequency is determined by the following
formula:
Bit Frequency = fPCLK / (2*(I2SCLH + I2SCLL))
Where fPCLK is the frequency of PCLK.
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The values for I2SCLL and I2SCLH do not have to be the same; the user can give different
duty cycles for SCL by setting these two registers. However, the value of the register must
ensure that the data rate is in the I2C data rate range of 0 to 400 kHz. Thus the values of
I2SCLL and I2SCLH have some restrictions and values for both registers greater than
three PCLKs are recommended.
I2C clock rates selection
Table 80:
Bit data rate (Kbit/sec) at fosc
I2SCLL+
CRSEL
7.373 MHz
3.6865 MHz 1.8433 MHz 12 MHz
6 MHz
6
0
-
307
154
-
-
7
0
-
263
132
-
-
8
0
-
230
115
-
375
I2SCLH
9
0
-
205
102
-
333
10
0
369
184
92
-
300
15
0
246
123
61
400
200
25
0
147
74
37
240
120
30
0
123
61
31
200
100
50
0
74
37
18
120
60
60
0
61
31
15
100
50
100
0
37
18
9
60
30
150
0
25
12
6
40
20
200
0
18
9
5
30
15
-
1
3.6 Kbps to
922 Kbps
Timer 1 in
mode 2
1.8 Kbps to
461 Kbps
Timer 1 in
mode 2
0.9 Kbps to
230 Kbps
Timer 1 in
mode 2
5.86 Kbps to
1500 Kbps
Timer 1 in
mode 2
2.93 Kbps to
750 Kbps
Timer 1 in
mode 2
12.6 I2C operation modes
12.6.1 Master Transmitter mode
In this mode data is transmitted from master to slave. Before the Master Transmitter mode
can be entered, I2CON must be initialized as follows:
I2C Control register (I2CON - address D8h)
Table 81:
Bit
value
7
6
5
4
3
2
1
0
-
I2EN
STA
STO
SI
AA
-
CRSEL
-
1
0
0
0
x
-
bit rate
CRSEL defines the bit rate. I2EN must be set to 1 to enable the I2C function. If the AA bit
is 0, it will not acknowledge its own slave address or the general call address in the event
of another device becoming master of the bus and it can not enter slave mode. STA, STO,
and SI bits must be cleared to 0.
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The first byte transmitted contains the slave address of the receiving device (7 bits) and
the data direction bit. In this case, the data direction bit (R/W) will be logic 0 indicating a
write. Data is transmitted 8 bits at a time. After each byte is transmitted, an acknowledge
bit is received. START and STOP conditions are output to indicate the beginning and the
end of a serial transfer.
The I2C-bus will enter Master Transmitter Mode by setting the STA bit. The I2C logic will
send the START condition as soon as the bus is free. After the START condition is
transmitted, the SI bit is set, and the status code in I2STAT should be 08h. This status
code must be used to vector to an interrupt service routine where the user should load the
slave address to I2DAT (Data Register) and data direction bit (SLA+W). The SI bit must be
cleared before the data transfer can continue.
When the slave address and R/W bit have been transmitted and an acknowledgment bit
has been received, the SI bit is set again, and the possible status codes are 18h, 20h, or
38h for the master mode or 68h, 78h, or 0B0h if the slave mode was enabled (setting
AA = Logic 1). The appropriate action to be taken for each of these status codes is shown
in Table 83.
S
slave address
R/W
A
DATA
logic 0 = write
logic 1 = read
from Master to Slave
from Slave to Master
A
DATA
A/A
P
data transferred
(n Bytes + acknowledge)
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
P = STOP condition
002aaa929
Fig 32. Format in the Master Transmitter mode.
12.6.2 Master Receiver mode
In the Master Receiver Mode, data is received from a slave transmitter. The transfer
started in the same manner as in the Master Transmitter Mode. When the START
condition has been transmitted, the interrupt service routine must load the slave address
and the data direction bit to I2C Data Register (I2DAT). The SI bit must be cleared before
the data transfer can continue.
When the slave address and data direction bit have been transmitted and an acknowledge
bit has been received, the SI bit is set, and the Status Register will show the status code.
For master mode, the possible status codes are 40H, 48H, or 38H. For slave mode, the
possible status codes are 68H, 78H, or B0H. Refer to Table 85 for details.
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S
slave address
R
A
logic 0 = write
logic 1 = read
DATA
A
DATA
A
P
data transferred
(n Bytes + acknowledge)
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
from Master to Slave
from Slave to Master
002aaa930
Fig 33. Format of Master Receiver mode.
After a repeated START condition, I2C-bus may switch to the Master Transmitter Mode.
S
SLA
R
A
logic 0 = write
logic 1 = read
DATA
A
DATA
A
RS
SLA
W
A
DATA
A
P
data transferred
(n Bytes + acknowledge)
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
P = STOP condition
SLA = slave address
RS = repeat START condition
from Master to Slave
from Slave to Master
002aaa931
Fig 34. A Master Receiver switches to Master Transmitter after sending Repeated Start.
12.6.3 Slave Receiver mode
In the Slave Receiver Mode, data bytes are received from a master transmitter. To
initialize the Slave Receiver Mode, the user should write the slave address to the Slave
Address Register (I2ADR) and the I2C Control Register (I2CON) should be configured as
follows:
I2C Control register (I2CON - address D8h)
Table 82:
Bit
value
7
6
5
4
3
2
1
0
-
I2EN
STA
STO
SI
AA
-
CRSEL
-
1
0
0
0
1
-
-
CRSEL is not used for slave mode. I2EN must be set = 1 to enable I2C function. AA bit
must be set = 1 to acknowledge its own slave address or the general call address. STA,
STO and SI are cleared to 0.
After I2ADR and I2CON are initialized, the interface waits until it is addressed by its own
address or general address followed by the data direction bit which is 0(W). If the direction
bit is 1(R), it will enter Slave Transmitter Mode. After the address and the direction bit have
been received, the SI bit is set and a valid status code can be read from the Status
Register(I2STAT). Refer to Table 86 for the status codes and actions.
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S
slave address
W
A
logic 0 = write
logic 1 = read
DATA
A
DATA
A/A
P/RS
data transferred
(n Bytes + acknowledge)
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
P = STOP condition
RS = repeated START condition
from Master to Slave
from Slave to Master
002aaa932
Fig 35. Format of Slave Receiver mode.
12.6.4 Slave Transmitter mode
The first byte is received and handled as in the Slave Receiver Mode. However, in this
mode, the direction bit will indicate that the transfer direction is reversed. Serial data is
transmitted via P1.3/SDA while the serial clock is input through P1.2/SCL. START and
STOP conditions are recognized as the beginning and end of a serial transfer. In a given
application, the I2C-bus may operate as a master and as a slave. In the slave mode, the
I2C hardware looks for its own slave address and the general call address. If one of these
addresses is detected, an interrupt is requested. When the microcontrollers wishes to
become the bus master, the hardware waits until the bus is free before the master mode is
entered so that a possible slave action is not interrupted. If bus arbitration is lost in the
master mode, the I2C-bus switches to the slave mode immediately and can detect its own
slave address in the same serial transfer.
S
slave address
R
A
logic 0 = write
logic 1 = read
from Master to Slave
from Slave to Master
DATA
A
DATA
A
P
data transferred
(n Bytes + acknowledge)
A = acknowledge (SDA LOW)
A = not acknowledge (SDA HIGH)
S = START condition
P = STOP condition
002aaa933
Fig 36. Format of Slave Transmitter mode.
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8
I2ADR
ADDRESS REGISTER
P1.3
COMPARATOR
INPUT
FILTER
P1.3/SDA
SHIFT REGISTER
OUTPUT
STAGE
ACK
I2DAT
BIT COUNTER /
ARBITRATION &
SYNC LOGIC
INPUT
FILTER
P1.2/SCL
SERIAL CLOCK
GENERATOR
OUTPUT
STAGE
CCLK
TIMING
AND
CONTROL
LOGIC
interrupt
INTERNAL BUS
8
timer 1
overflow
P1.2
I2CON
I2SCLH
I2SCLL
CONTROL REGISTERS &
SCL DUTY CYCLE REGISTERS
8
status bus
I2STAT
STATUS
DECODER
STATUS REGISTER
8
002aaa899
Fig 37. I2C serial interface block diagram.
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Table 83:
Master Transmitter mode
Status code
(I2STAT)
Status of the I2C
hardware
Next action taken by I2C
hardware
Application software response
to/from I2DAT
to I2CON
STA
STO
SI
AA
08H
A START
condition has
been transmitted
Load SLA+W
x
0
0
x
SLA+W will be transmitted;
ACK bit will be received
10H
A repeat START
condition has
been transmitted
Load SLA+W or
x
0
0
x
As above; SLA+W will be
transmitted; I2C-bus switches
to Master Receiver Mode
SLA+W has been Load data byte or 0
transmitted; ACK
has been received no I2DAT action or 1
0
0
x
Data byte will be transmitted;
ACK bit will be received
0
0
x
Repeated START will be
transmitted;
no I2DAT action or 0
1
0
x
STOP condition will be
transmitted;
18h
Load SLA+R
STO flag will be reset
20h
28h
no I2DAT action
1
1
0
x
STOP condition followed by a
START condition will be
transmitted; STO flag will be
reset.
Load data byte or
0
0
0
x
Data byte will be transmitted;
ACK bit will be received
no I2DAT action or 1
0
0
x
Repeated START will be
transmitted;
no I2DAT action or 0
1
0
x
STOP condition will be
transmitted; STO flag will be
reset
no I2DAT action
1
1
0
x
STOP condition followed by a
START condition will be
transmitted; STO flag will be
reset
Data byte in I2DAT Load data byte or 0
has been
transmitted; ACK
has been received no I2DAT action or 1
0
0
x
Data byte will be transmitted;
0
0
x
Repeated START will be
transmitted;
no I2DAT action or 0
1
0
x
STOP condition will be
transmitted; STO flag will be
reset
no I2DAT action
1
0
x
STOP condition followed by a
START condition will be
transmitted; STO flag will be
reset
SLA+W has been
transmitted;
NOT-ACK has
been received
1
ACK bit will be received
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Table 83:
Master Transmitter mode …continued
Status code
(I2STAT)
Status of the I2C
hardware
to/from I2DAT
to I2CON
STA
30h
Data byte in I2DAT Load data byte or 0
has been
transmitted, NOT
no I2DAT action or 1
ACK has been
received
no I2DAT action or 0
38H
Table 84:
Arbitration lost in
SLA+R/W or data
bytes
Next action taken by I2C
hardware
Application software response
STO
SI
AA
0
0
x
Data byte will be transmitted;
ACK bit will be received
0
0
x
Repeated START will be
transmitted;
1
0
x
STOP condition will be
transmitted; STO flag will be
reset
no I2DAT action
1
1
0
x
STOP condition followed by a
START condition will be
transmitted. STO flag will be
reset.
No I2DAT action
or
0
0
0
x
I2C-bus will be released; not
addressed slave will be entered
No I2DAT action
1
0
0
x
A START condition will be
transmitted when the bus
becomes free.
Master Receiver mode
Status code
(I2STAT)
Status of the I2C
hardware
Application software response
STA STO SI
STA
08H
A START
condition has
been transmitted
Load SLA+R
x
0
0
x
SLA+R will be transmitted; ACK bit
will be received
10H
A repeat START
condition has
been transmitted
Load SLA+R or
x
0
0
x
As above
Arbitration lost in
NOT ACK bit
no I2DAT action or 0
0
0
x
I2C-bus will be released; it will enter a
slave mode
no I2DAT action
1
0
0
x
A START condition will be
transmitted when the bus becomes
free
SLA+R has been no I2DAT action or 0
transmitted; ACK
has been received no I2DAT action or 0
0
0
0
Data byte will be received; NOT ACK
bit will be returned
0
0
1
Data byte will be received; ACK bit
will be returned
SLA+R has been
transmitted; NOT
ACK has been
received
1
0
0
x
Repeated START will be transmitted
no I2DAT action or 0
1
0
x
STOP condition will be transmitted;
STO flag will be reset
no I2DAT action or 1
1
0
x
STOP condition followed by a START
condition will be transmitted; STO
flag will be reset
38H
40h
48h
to/from I2DAT
Next action taken by I2C hardware
to I2CON
SLA+W will be transmitted; I2C-bus
will be switched to Master Transmitter
Mode
Load SLA+W
No I2DAT action
or
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Table 84:
Master Receiver mode …continued
Status code
(I2STAT)
50h
58h
Table 85:
Status of the I2C
hardware
to/from I2DAT
to I2CON
STA STO SI
STA
Data byte has
been received;
ACK has been
returned
Read data byte
0
0
0
0
Data byte will be received; NOT ACK
bit will be returned
read data byte
0
0
0
1
Data byte will be received; ACK bit
will be returned
Data byte has
been received;
NACK has been
returned
Read data byte or 1
0
0
x
Repeated START will be transmitted;
read data byte or
0
1
0
x
STOP condition will be transmitted;
STO flag will be reset
read data byte
1
1
0
x
STOP condition followed by a START
condition will be transmitted; STO
flag will be reset
Slave Receiver mode
Status code
(I2STAT)
Status of the I2C
hardware
68H
70H
78H
80H
Next action taken by I2C hardware
Application software response
to/from I2DAT
to I2CON
STA
60H
Next action taken by I2C hardware
Application software response
STO
SI
AA
no I2DAT action or x
0
0
0
Data byte will be received and NOT
ACK will be returned
no I2DAT action
x
0
0
1
Data byte will be received and ACK
will be returned
Arbitration lost in No I2DAT action
SLA+R/Was
or
master; Own
no I2DAT action
SLA+W has been
received, ACK
returned
x
0
0
0
Data byte will be received and NOT
ACK will be returned
x
0
0
1
Data byte will be received and ACK
will be returned
x
0
0
0
Data byte will be received and NOT
ACK will be returned
x
0
0
1
Data byte will be received and ACK
will be returned
no I2DAT action or x
0
0
0
Data byte will be received and NOT
ACK will be returned
no I2DAT action
x
0
0
1
Data byte will be received and ACK
will be returned
Previously
Read data byte or x
addressed with
own SLA address; read data byte
x
Data has been
received; ACK
has been returned
0
0
0
Data byte will be received and NOT
ACK will be returned
0
0
1
Data byte will be received; ACK bit
will be returned
Own SLA+W has
been received;
ACK has been
received
No I2DAT action
General call
address(00H) has or
been received,
no I2DAT action
ACK has been
returned
Arbitration lost in
SLA+R/W as
master; General
call address has
been received,
ACK bit has been
returned
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Table 85:
Slave Receiver mode …continued
Status code
(I2STAT)
Status of the I2C
hardware
to/from I2DAT
to I2CON
STA
88H
Next action taken by I2C hardware
Application software response
STO
SI
AA
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
general address
0
0
1
Switched to not addressed SLA
mode; Own SLA will be recognized;
general call address will be
recognized if I2ADR.0 = 1
1
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address. A START
condition will be transmitted when
the bus becomes free
1
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1. A
START condition will be transmitted
when the bus becomes free.
Read data byte or x
Previously
addressed with
General call; Data read data byte
x
has been
received; ACK
has been returned
0
0
0
Data byte will be received and NOT
ACK will be returned
0
0
1
Data byte will be received and ACK
will be returned
Previously
Read data byte
addressed with
General call; Data
has been
read data byte
received; NACK
has been returned
0
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address
0
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1.
read data byte
1
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address. A START
condition will be transmitted when
the bus becomes free.
read data byte
1
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1. A
START condition will be transmitted
when the bus becomes free.
Previously
Read data byte or 0
addressed with
own SLA address;
Data has been
read data byte
0
received; NACK
or
has been returned
read data byte
or
read data byte
90H
98H
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Table 85:
Slave Receiver mode …continued
Status code
(I2STAT)
A0H
Table 86:
B0h
B8H
Next action taken by I2C hardware
Application software response
to/from I2DAT
to I2CON
STA
STO
SI
AA
A STOP condition No I2DAT action
or repeated
START condition
has been received no I2DAT action
while still
addressed as
SLA/REC or
SLA/TRX
no I2DAT action
0
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address
0
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1.
1
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address. A START
condition will be transmitted when
the bus becomes free.
no I2DAT action
1
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1. A
START condition will be transmitted
when the bus becomes free.
Slave Transmitter mode
Status code
(I2STAT)
A8h
Status of the I2C
hardware
Status of the I2C
hardware
Application software response
Next action taken by I2C
to/from I2DAT
hardware
to I2CON
STA
STO
SI
AA
Load data byte or
x
0
0
0
Last data byte will be transmitted
and ACK bit will be received
load data byte
x
0
0
1
Data byte will be transmitted; ACK
will be received
Arbitration lost in Load data byte or
SLA+R/W as
master; Own
load data byte
SLA+R has been
received, ACK
has been returned
x
0
0
0
Last data byte will be transmitted
and ACK bit will be received
x
0
0
1
Data byte will be transmitted; ACK
bit will be received
Data byte in
Load data byte or
I2DAT has been
transmitted; ACK load data byte
has been received
x
0
0
0
Last data byte will be transmitted
and ACK bit will be received
x
0
0
1
Data byte will be transmitted; ACK
will be received
Own SLA+R has
been received;
ACK has been
returned
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Table 86:
Slave Transmitter mode …continued
Status code
(I2STAT)
C0H
C8H
Status of the I2C
hardware
Application software response
Next action taken by I2C
to/from I2DAT
hardware
to I2CON
STA
STO
SI
AA
0
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address.
no I2DAT action or 0
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1.
no I2DAT action or 1
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address. A START
condition will be transmitted when
the bus becomes free.
no I2DAT action
1
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1. A
START condition will be transmitted
when the bus becomes free.
0
Last data byte in No I2DAT action
or
I2DAT has been
transmitted
(AA = 0); ACK has no I2DAT action or 0
been received
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address.
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1.
no I2DAT action or 1
0
0
0
Switched to not addressed SLA
mode; no recognition of own SLA or
General call address. A START
condition will be transmitted when
the bus becomes free.
no I2DAT action
0
0
1
Switched to not addressed SLA
mode; Own slave address will be
recognized; General call address
will be recognized if I2ADR.0 = 1. A
START condition will be transmitted
when the bus becomes free.
Data byte in
I2DAT has been
transmitted;
NACK has been
received
No I2DAT action
or
1
13. Serial Peripheral Interface (SPI)
The P89LPC938 provides another high-speed serial communication interface, the SPI
interface. SPI is a full-duplex, high-speed, synchronous communication bus with two
operation modes: Master mode and Slave mode. Up to 3 Mbit/s can be supported in either
Master or Slave mode. It has a Transfer Completion Flag and Write Collision Flag
Protection.
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S
M
CPU clock
8-BIT SHIFT REGISTER
clock
MSTR
SPR0
SPICLK
P2.5
SS
P2.4
SPR0
SPR1
CPOL
CPHA
MSTR
SSIG
WCOL
DORD
MSTR
SPEN
SPI CONTROL
SPEN
SPR1
S
M
CLOCK LOGIC
MOSI
P2.2
SPEN
SPI clock (master)
SELECT
SPIF
PIN
CONTROL
LOGIC
READ DATA BUFFER
DIVIDER
BY 4, 16, 64, 128
MISO
P2.3
M
S
SPI CONTROL REGISTER
SPI STATUS REGISTER
SPI
interrupt
request
internal
data
bus
002aaa900
Fig 38. SPI block diagram.
The SPI interface has four pins: SPICLK, MOSI, MISO and SS:
• SPICLK, MOSI and MISO are typically tied together between two or more SPI
devices. Data flows from master to slave on the MOSI (Master Out Slave In) pin and
flows from slave to master on the MISO (Master In Slave Out) pin. The SPICLK signal
is output in the master mode and is input in the slave mode. If the SPI system is
disabled, i.e. SPEN (SPCTL.6) = 0 (reset value), these pins are configured for port
functions.
• SS is the optional slave select pin. In a typical configuration, an SPI master asserts
one of its port pins to select one SPI device as the current slave. An SPI slave device
uses its SS pin to determine whether it is selected. The SS is ignored if any of the
following conditions are true:
– If the SPI system is disabled, i.e. SPEN (SPCTL.6) = 0 (reset value)
– If the SPI is configured as a master, i.e., MSTR (SPCTL.4) = 1, and P2.4 is
configured as an output (via the P2M1.4 and P2M2.4 SFR bits);
– If the SS pin is ignored, i.e. SSIG (SPCTL.7) bit = 1, this pin is configured for port
functions.
Note that even if the SPI is configured as a master (MSTR = 1), it can still be converted to
a slave by driving the SS pin low (if P2.4 is configured as input and SSIG = 0). Should this
happen, the SPIF bit (SPSTAT.7) will be set (see Section 13.4 “Mode change on SS”)
Typical connections are shown in Figure 39 to Figure 41.
Table 87:
SPI Control register (SPCTL - address E2h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
SSIG
SPEN
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
Reset
0
0
0
0
0
1
0
0
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Table 88:
SPI Control register (SPCTL - address E2h) bit description
Bit Symbol
Description
0
SPR0
SPI Clock Rate Select
1
SPR1
SPR1, SPR0:
00 — CCLK⁄4
01 — CCLK⁄16
10 — CCLK⁄64
11 — CCLK⁄128
2
CPHA
SPI Clock PHAse select (see Figure 42 to Figure 45):
1 — Data is driven on the leading edge of SPICLK, and is sampled on the trailing
edge.
0 — Data is driven when SS is low (SSIG = 0) and changes on the trailing edge of
SPICLK, and is sampled on the leading edge. (Note: If SSIG = 1, the operation is
not defined.
3
SPI Clock POLarity (see Figure 42 to Figure 45):
CPOL
1 — SPICLK is high when idle. The leading edge of SPICLK is the falling edge and
the trailing edge is the rising edge.
0 — SPICLK is low when idle. The leading edge of SPICLK is the rising edge and
the trailing edge is the falling edge.
4
MSTR
5
DORD
Master/Slave mode Select (see Table 92).
SPI Data ORDer.
1 — The LSB of the data word is transmitted first.
0 — The MSB of the data word is transmitted first.
6
SPEN
SPI Enable.
1 — The SPI is enabled.
0 — The SPI is disabled and all SPI pins will be port pins.
7
SSIG
SS IGnore.
1 — MSTR (bit 4) decides whether the device is a master or slave.
0 — The SS pin decides whether the device is master or slave. The SS pin can be
used as a port pin (see Table 92).
Table 89:
SPI Status register (SPSTAT - address E1h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
SPIF
WCOL
-
-
-
-
-
-
Reset
0
0
x
x
x
x
x
x
Table 90:
Bit
SPI Status register (SPSTAT - address E1h) bit description
Symbol
Description
0:5 -
reserved
6
WCOL
SPI Write Collision Flag. The WCOL bit is set if the SPI data register, SPDAT, is
written during a data transfer (see Section 13.5 “Write collision”). The WCOL flag
is cleared in software by writing a logic 1 to this bit.
7
SPIF
SPI Transfer Completion Flag. When a serial transfer finishes, the SPIF bit is set
and an interrupt is generated if both the ESPI (IEN1.3) bit and the EA bit are set. If
SS is an input and is driven low when SPI is in master mode, and SSIG = 0, this bit
will also be set (see Section 13.4 “Mode change on SS”). The SPIF flag is cleared
in software by writing a logic 1 to this bit.
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Table 91:
Bit
SPI Data register (SPDAT - address E3h) bit allocation
7
Symbol
MSB
Reset
0
6
5
4
3
2
1
0
0
0
0
0
0
0
0
LSB
master
8-BIT SHIFT
REGISTER
slave
MISO
MISO
MOSI
MOSI
SPICLK
SPI CLOCK
GENERATOR
PORT
8-BIT SHIFT
REGISTER
SPICLK
SS
002aaa901
Fig 39. SPI single master single slave configuration.
In Figure 39, SSIG (SPCTL.7) for the slave is logic 0, and SS is used to select the slave.
The SPI master can use any port pin (including P2.4/SS) to drive the SS pin.
master
8-BIT SHIFT
REGISTER
slave
MISO
MISO
MOSI
MOSI
SPICLK
SPI CLOCK
GENERATOR
SS
8-BIT SHIFT
REGISTER
SPICLK
SS
SPI CLOCK
GENERATOR
002aaa902
Fig 40. SPI dual device configuration, where either can be a master or a slave.
Figure 40 shows a case where two devices are connected to each other and either device
can be a master or a slave. When no SPI operation is occurring, both can be configured
as masters (MSTR = 1) with SSIG cleared to 0 and P2.4 (SS) configured in
quasi-bidirectional mode. When a device initiates a transfer, it can configure P2.4 as an
output and drive it low, forcing a mode change in the other device (see Section 13.4 “Mode
change on SS”) to slave.
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master
slave
8-BIT SHIFT
REGISTER
MISO
MISO
MOSI
MOSI
SPICLK
SPI CLOCK
GENERATOR
8-BIT SHIFT
REGISTER
SPICLK
SS
port
slave
MISO
MOSI
8-BIT SHIFT
REGISTER
SPICLK
port
SS
002aaa903
Fig 41. SPI single master multiple slaves configuration.
In Figure 41, SSIG (SPCTL.7) bits for the slaves are logic 0, and the slaves are selected
by the corresponding SS signals. The SPI master can use any port pin (including
P2.4/SS) to drive the SS pins.
13.1 Configuring the SPI
Table 92 shows configuration for the master/slave modes as well as usages and directions
for the modes.
Table 92:
SPI master and slave selection
SPEN
SSIG
SS Pin MSTR
Master
MISO
or Slave
Mode
MOSI
SPICLK Remarks
0
x
P2.4[1]
x
SPI
P2.3[1]
Disabled
P2.2[1]
P2.5[1]
SPI disabled. P2.2, P2.3, P2.4, P2.5 are used
as port pins.
1
0
0
0
Slave
output
input
input
Selected as slave.
1
0
1
0
Slave
Hi-Z
input
input
Not selected. MISO is high-impedance to avoid
bus contention.
1
0
0
1 (->
0)[2]
Slave
output
input
input
P2.4/SS is configured as an input or
quasi-bidirectional pin. SSIG is 0. Selected
externally as slave if SS is selected and is
driven low. The MSTR bit will be cleared to
logic 0 when SS becomes low.
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Table 92:
SPI master and slave selection …continued
SPEN
SSIG
SS Pin MSTR
1
0
1
1
Master
MISO
or Slave
Mode
MOSI
SPICLK Remarks
Master
Hi-Z
Hi-Z
MOSI and SPICLK are at high-impedance to
avoid bus contention when the MAster is idle.
The application must pull-up or pull-down
SPICLK (depending on CPOL - SPCTL.3) to
avoid a floating SPICLK.
output
output
MOSI and SPICLK are push-pull when the
Master is active.
input
(idle)
Master
(active)
1
1
P2.4[1]
1
1
P2.4[1]
0
Slave
output
input
input
1
Master
input
output
output
[1]
Selected as a port function
[2]
The MSTR bit changes to logic 0 automatically when SS becomes low in input mode and SSIG is logic 0.
13.2 Additional considerations for a slave
When CPHA equals zero, SSIG must be logic 0 and the SS pin must be negated and
reasserted between each successive serial byte. If the SPDAT register is written while SS
is active (low), a write collision error results. The operation is undefined if CPHA is logic 0
and SSIG is logic 1.
When CPHA equals one, SSIG may be set to logic 1. If SSIG = 0, the SS pin may remain
active low between successive transfers (can be tied low at all times). This format is
sometimes preferred in systems having a single fixed master and a single slave driving the
MISO data line.
13.3 Additional considerations for a master
In SPI, transfers are always initiated by the master. If the SPI is enabled (SPEN = 1) and
selected as master, writing to the SPI data register by the master starts the SPI clock
generator and data transfer. The data will start to appear on MOSI about one half SPI
bit-time to one SPI bit-time after data is written to SPDAT.
Note that the master can select a slave by driving the SS pin of the corresponding device
low. Data written to the SPDAT register of the master is shifted out of the MOSI pin of the
master to the MOSI pin of the slave, at the same time the data in SPDAT register in slave
side is shifted out on MISO pin to the MISO pin of the master.
After shifting one byte, the SPI clock generator stops, setting the transfer completion flag
(SPIF) and an interrupt will be created if the SPI interrupt is enabled (ESPI, or IEN1.3 = 1).
The two shift registers in the master CPU and slave CPU can be considered as one
distributed 16-bit circular shift register. When data is shifted from the master to the slave,
data is also shifted in the opposite direction simultaneously. This means that during one
shift cycle, data in the master and the slave are interchanged.
13.4 Mode change on SS
If SPEN = 1, SSIG = 0 and MSTR = 1, the SPI is enabled in master mode. The SS pin can
be configured as an input (P2M2.4, P2M1.4 = 00) or quasi-bidirectional (P2M2.4, P2M1.4
= 01). In this case, another master can drive this pin low to select this device as an SPI
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slave and start sending data to it. To avoid bus contention, the SPI becomes a slave. As a
result of the SPI becoming a slave, the MOSI and SPICLK pins are forced to be an input
and MISO becomes an output.
The SPIF flag in SPSTAT is set, and if the SPI interrupt is enabled, an SPI interrupt will
occur.
User software should always check the MSTR bit. If this bit is cleared by a slave select
and the user wants to continue to use the SPI as a master, the user must set the MSTR bit
again, otherwise it will stay in slave mode.
13.5 Write collision
The SPI is single buffered in the transmit direction and double buffered in the receive
direction. New data for transmission can not be written to the shift register until the
previous transaction is complete. The WCOL (SPSTAT.6) bit is set to indicate data
collision when the data register is written during transmission. In this case, the data
currently being transmitted will continue to be transmitted, but the new data, i.e., the one
causing the collision, will be lost.
While write collision is detected for both a master or a slave, it is uncommon for a master
because the master has full control of the transfer in progress. The slave, however, has no
control over when the master will initiate a transfer and therefore collision can occur.
For receiving data, received data is transferred into a parallel read data buffer so that the
shift register is free to accept a second character. However, the received character must
be read from the Data Register before the next character has been completely shifted in.
Otherwise. the previous data is lost.
WCOL can be cleared in software by writing a logic 1 to the bit.
13.6 Data mode
Clock Phase Bit (CPHA) allows the user to set the edges for sampling and changing data.
The Clock Polarity bit, CPOL, allows the user to set the clock polarity. Figure 42 to
Figure 45 show the different settings of Clock Phase bit CPHA.
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1
Clock cycle
2
3
4
5
6
7
8
SPICLK (CPOL = 0)
SPICLK (CPOL = 1)
MOSI (input)
MISO (output)
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
(1)
SS (if SSIG bit = 0)
002aaa934
(1) Not defined
Fig 42. SPI slave transfer format with CPHA = 0.
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1
Clock cycle
2
3
4
5
6
7
8
SPICLK (CPOL = 0)
SPICLK (CPOL = 1)
MOSI (input)
MISO (output)
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
MSB
6
5
4
3
2
1
LSB
LSB
1
2
3
4
5
6
MSB
DORD = 0
DORD = 1
(1)
SS (if SSIG bit = 0)
002aaa935
(1) Not defined
Fig 43. SPI slave transfer format with CPHA = 1.
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1
Clock cycle
2
3
4
5
6
7
8
SPICLK (CPOL = 0)
SPICLK (CPOL = 1)
MOSI (input)
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
MISO (output)
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
SS (if SSIG bit = 0)
002aaa936
(1) Not defined
Fig 44. SPI master transfer format with CPHA = 0.
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1
Clock cycle
2
3
4
5
6
7
8
SPICLK (CPOL = 0)
SPICLK (CPOL = 1)
MOSI (input)
MISO (output)
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
DORD = 0
MSB
6
5
4
3
2
1
LSB
DORD = 1
LSB
1
2
3
4
5
6
MSB
SS (if SSIG bit = 0)
002aaa937
(1) Not defined
Fig 45. SPI master transfer format with CPHA = 1.
13.7 SPI clock prescaler select
The SPI clock prescalar selection uses the SPR1-SPR0 bits in the SPCTL register (see
Table 88).
14. Analog comparators
Two analog comparators are provided on the P89LPC938. Input and output options allow
use of the comparators in a number of different configurations. Comparator operation is
such that the output is a logic 1 (which may be read in a register and/or routed to a pin)
when the positive input (one of two selectable pins) is greater than the negative input
(selectable from a pin or an internal reference voltage). Otherwise the output is a zero.
Each comparator may be configured to cause an interrupt when the output value changes.
14.1 Comparator configuration
Each comparator has a control register, CMP1 for comparator 1 and CMP2 for comparator
2. The control registers are identical and are shown in Table 94.
The overall connections to both comparators are shown in Figure 46. There are eight
possible configurations for each comparator, as determined by the control bits in the
corresponding CMPn register: CPn, CNn, and OEn. These configurations are shown in
Figure 47.
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When each comparator is first enabled, the comparator output and interrupt flag are not
guaranteed to be stable for 10 microseconds. The corresponding comparator interrupt
should not be enabled during that time, and the comparator interrupt flag must be cleared
before the interrupt is enabled in order to prevent an immediate interrupt service.
Table 93:
Bit
Comparator Control register (CMP1 - address ACh, CMP2 - address ADh) bit
allocation
7
6
5
4
3
2
1
0
Symbol
-
-
CEn
CPn
CNn
OEn
COn
CMFn
Reset
x
x
0
0
0
0
0
0
Table 94:
Comparator Control register (CMP1 - address ACh, CMP2 - address ADh) bit
description
Bit
Symbol
Description
0
CMFn
Comparator interrupt flag. This bit is set by hardware whenever the comparator
output COn changes state. This bit will cause a hardware interrupt if enabled.
Cleared by software.
1
COn
Comparator output, synchronized to the CPU clock to allow reading by software.
2
OEn
Output enable. When logic 1, the comparator output is connected to the CMPn pin
if the comparator is enabled (CEn = 1). This output is asynchronous to the CPU
clock.
3
CNn
Comparator negative input select. When logic 0, the comparator reference pin
CMPREF is selected as the negative comparator input. When logic 1, the internal
comparator reference, Vref, is selected as the negative comparator input.
4
CPn
Comparator positive input select. When logic 0, CINnA is selected as the positive
comparator input. When logic 1, CINnB is selected as the positive comparator
input.
5
CEn
Comparator enable. When set, the corresponding comparator function is enabled.
Comparator output is stable 10 microseconds after CEn is set.
6:7 -
reserved
CP1
comparator 1
OE1
(P0.4) CIN1A
(P0.3) CIN1B
CO1
CMP1 (P0.6)
(P0.5) CMPREF
change detect
VREF
CMF1
CN1
interrupt
change detect
CP2
comparator 2
EC
CMF2
(P0.2) CIN2A
(P0.1) CIN2B
CMP2 (P0.0)
CO2
OE2
CN2
002aaa904
Fig 46. Comparator input and output connections.
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14.2 Internal reference voltage
An internal reference voltage, Vref, may supply a default reference when a single
comparator input pin is used. Please refer to the P89LPC938 data sheet for specifications
14.3 Comparator input pins
Comparator input and reference pins maybe be used as either digital I/O or as inputs to
the comparator. When used as digital I/O these pins are 5 V tolerant. However, when
selected as comparator input signals in CMPn lower voltage limits apply. Please refer to
the P89LPC938 data sheet for specifications.
14.4 Comparator interrupt
Each comparator has an interrupt flag CMFn contained in its configuration register. This
flag is set whenever the comparator output changes state. The flag may be polled by
software or may be used to generate an interrupt. The two comparators use one common
interrupt vector. The interrupt will be generated when the interrupt enable bit EC in the
IEN1 register is set and the interrupt system is enabled via the EA bit in the IEN0 register.
If both comparators enable interrupts, after entering the interrupt service routine, the user
will need to read the flags to determine which comparator caused the interrupt.
When a comparator is disabled the comparator’s output, COx, goes high. If the
comparator output was low and then is disabled, the resulting transition of the comparator
output from a low to high state will set the comparator flag, CMFx. This will cause an
interrupt if the comparator interrupt is enabled. The user should therefore disable the
comparator interrupt prior to disabling the comparator. Additionally, the user should clear
the comparator flag, CMFx, after disabling the comparator.
14.5 Comparators and power reduction modes
Either or both comparators may remain enabled when Power-down mode or Idle mode is
activated, but both comparators are disabled automatically in Total Power-down mode.
If a comparator interrupt is enabled (except in Total Power-down mode), a change of the
comparator output state will generate an interrupt and wake-up the processor. If the
comparator output to a pin is enabled, the pin should be configured in the push-pull mode
in order to obtain fast switching times while in Power-down mode. The reason is that with
the oscillator stopped, the temporary strong pull-up that normally occurs during switching
on a quasi-bidirectional port pin does not take place.
Comparators consume power in Power-down mode and Idle mode, as well as in the
normal operating mode. This should be taken into consideration when system power
consumption is an issue. To minimize power consumption, the user can power-down the
comparators by disabling the comparators and setting PCONA.5 to logic 1, or simply
putting the device in Total Power-down mode.
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CINnA
CMPREF
COn
CINnA
CMPREF
CINnA
VREF (1.23 V)
b. CPn, CNn, OEn = 0 0 1
COn
CINnA
VREF (1.23 V)
002aaa621
c. CPn, CNn, OEn = 0 1 0
CINnB
CMPn
002aaa622
CINnB
CMPREF
002aaa623
e. CPn, CNn, OEn = 1 0 0
CINnB
VREF (1.23V)
COn
d. CPn, CNn, OEn = 0 1 1
COn
CMPREF
CMPn
002aaa620
002aaa618
a. CPn, CNn, OEn = 0 0 0
COn
COn
CMPn
002aaa624
f. CPn, CNn, OEn = 1 0 1
COn
002aaa625
g. CPn, CNn, OEn = 1 1 0
CINnB
VREF (1.23 V)
COn
CMPn
002aaa626
h. CPn, CNn, OEn = 1 1 1
Fig 47. Comparator configurations.
14.6 Comparators configuration example
The code shown below is an example of initializing one comparator. Comparator 1 is
configured to use the CIN1A and CMPREF inputs, outputs the comparator result to the
CMP1 pin, and generates an interrupt when the comparator output changes.
CMPINIT:
MOV PT0AD,#030h
ANL P0M2,#0CFh
ORL P0M1,#030h
MOV CMP1,#024h
CALL delay10us
ANL CMP1,#0FEh
SETB EC
SETB EA
RET
;Disable digital INPUTS on CIN1A, CMPREF.
;Disable digital OUTPUTS on pins that are used
;for analog functions: CIN1A, CMPREF.
;Turn on comparator 1 and set up for:
;Positive input on CIN1A.
;Negative input from CMPREF pin.
;Output to CMP1 pin enabled.
;The comparator needs at least 10 microseconds before use.
;Clear comparator 1 interrupt flag.
;Enable the comparator interrupt,
;Enable the interrupt system (if needed).
;Return to caller.
The interrupt routine used for the comparator must clear the interrupt flag (CMF1 in this
case) before returning
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15. Keypad interrupt (KBI)
The Keypad Interrupt function is intended primarily to allow a single interrupt to be
generated when Port 0 is equal to or not equal to a certain pattern. This function can be
used for bus address recognition or keypad recognition. The user can configure the port
via SFRs for different tasks.
There are three SFRs used for this function. The Keypad Interrupt Mask Register
(KBMASK) is used to define which input pins connected to Port 0 are enabled to trigger
the interrupt. The Keypad Pattern Register (KBPATN) is used to define a pattern that is
compared to the value of Port 0. The Keypad Interrupt Flag (KBIF) in the Keypad Interrupt
Control Register (KBCON) is set when the condition is matched while the Keypad
Interrupt function is active. An interrupt will be generated if it has been enabled by setting
the EKBI bit in IEN1 register and EA = 1. The PATN_SEL bit in the Keypad Interrupt
Control Register (KBCON) is used to define equal or not-equal for the comparison.
In order to use the Keypad Interrupt as an original KBI function like in the 87LPC76x
series, the user needs to set KBPATN = 0FFH and PATN_SEL = 0 (not equal), then any
key connected to Port0 which is enabled by KBMASK register is will cause the hardware
to set KBIF = 1 and generate an interrupt if it has been enabled. The interrupt may be
used to wake-up the CPU from Idle or Power-down modes. This feature is particularly
useful in handheld, battery powered systems that need to carefully manage power
consumption yet also need to be convenient to use.
In order to set the flag and cause an interrupt, the pattern on Port 0 must be held longer
than 6 CCLKs
Table 95:
Keypad Pattern register (KBPATN - address 93h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
KBPATN.7
KBPATN.6
KBPATN.5
KBPATN.4
KBPATN.3
KBPATN.2
KBPATN.1
KBPATN.0
Reset
1
1
1
1
1
1
1
1
Table 96:
Keypad Pattern register (KBPATN - address 93h) bit description
Bit Symbol
Access Description
0:7 KBPATN.7:0
R/W
Table 97:
Pattern bit 0 - bit 7
Keypad Control register (KBCON - address 94h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
-
-
-
-
PATN_SEL
KBIF
Reset
x
x
x
x
x
x
0
0
Table 98:
Keypad Control register (KBCON - address 94h) bit description
Bit Symbol
Access Description
0
KBIF
R/W
Keypad Interrupt Flag. Set when Port 0 matches user defined conditions specified in KBPATN,
KBMASK, and PATN_SEL. Needs to be cleared by software by writing logic 0.
1
PATN_SEL
R/W
Pattern Matching Polarity selection. When set, Port 0 has to be equal to the user-defined
Pattern in KBPATN to generate the interrupt. When clear, Port 0 has to be not equal to the
value of KBPATN register to generate the interrupt.
-
reserved
2:7 -
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Table 99:
Keypad Interrupt Mask register (KBMASK - address 86h) bit allocation
Bit
7
6
Symbol
KBMASK.7
KBMASK.6
Reset
0
0
5
4
3
2
1
0
KBMASK.5
KBMASK.4
KBMASK.3
KBMASK.2
KBMASK.1
KBMASK.0
0
0
0
0
0
0
Table 100: Keypad Interrupt Mask register (KBMASK - address 86h) bit description
Bit Symbol
Description
0
KBMASK.0
When set, enables P0.0 as a cause of a Keypad Interrupt.
1
KBMASK.1
When set, enables P0.1 as a cause of a Keypad Interrupt.
2
KBMASK.2
When set, enables P0.2 as a cause of a Keypad Interrupt.
3
KBMASK.3
When set, enables P0.3 as a cause of a Keypad Interrupt.
4
KBMASK.4
When set, enables P0.4 as a cause of a Keypad Interrupt.
5
KBMASK.5
When set, enables P0.5 as a cause of a Keypad Interrupt.
6
KBMASK.6
When set, enables P0.6 as a cause of a Keypad Interrupt.
7
KBMASK.7
When set, enables P0.7 as a cause of a Keypad Interrupt.
[1]
The Keypad Interrupt must be enabled in order for the settings of the KBMASK register to be effective.
16. Watchdog timer (WDT)
The watchdog timer subsystem protects the system from incorrect code execution by
causing a system reset when it underflows as a result of a failure of software to feed the
timer prior to the timer reaching its terminal count. The watchdog timer can only be reset
by a power-on reset.
16.1 Watchdog function
The user has the ability using the WDCON and UCFG1 registers to control the run /stop
condition of the WDT, the clock source for the WDT, the prescaler value, and whether the
WDT is enabled to reset the device on underflow. In addition, there is a safety mechanism
which forces the WDT to be enabled by values programmed into UCFG1 either through
IAP or a commercial programmer.
The WDTE bit (UCFG1.7), if set, enables the WDT to reset the device on underflow.
Following reset, the WDT will be running regardless of the state of the WDTE bit.
The WDRUN bit (WDCON.2) can be set to start the WDT and cleared to stop the WDT.
Following reset this bit will be set and the WDT will be running. All writes to WDCON need
to be followed by a feed sequence (see Section 16.2). Additional bits in WDCON allow the
user to select the clock source for the WDT and the prescaler.
When the timer is not enabled to reset the device on underflow, the WDT can be used in
‘timer mode’ and be enabled to produce an interrupt (IEN0.6) if desired
The Watchdog Safety Enable bit, WDSE (UCFG1.4) along with WDTE, is designed to
force certain operating conditions at power-up. Refer to Table 101 for details.
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Figure 50 shows the watchdog timer in watchdog mode. It consists of a programmable
13-bit prescaler, and an 8-bit down counter. The down counter is clocked (decremented)
by a tap taken from the prescaler. The clock source for the prescaler is either PCLK or the
watchdog oscillator selected by the WDCLK bit in the WDCON register. (Note that
switching of the clock sources will not take effect immediately - see Section 16.3).
The watchdog asserts the watchdog reset when the watchdog count underflows and the
watchdog reset is enabled. When the watchdog reset is enabled, writing to WDL or
WDCON must be followed by a feed sequence for the new values to take effect.
If a watchdog reset occurs, the internal reset is active for at least one watchdog clock
cycle (PCLK or the watchdog oscillator clock). If CCLK is still running, code execution will
begin immediately after the reset cycle. If the processor was in Power-down mode, the
watchdog reset will start the oscillator and code execution will resume after the oscillator
is stable.
Table 101: Watchdog timer configuration
WDTE WDSE FUNCTION
0
x
The watchdog reset is disabled. The timer can be used as an internal timer and
can be used to generate an interrupt. WDSE has no effect.
1
0
The watchdog reset is enabled. The user can set WDCLK to choose the clock
source.
1
1
The watchdog reset is enabled, along with additional safety features:
1. WDCLK is forced to 1 (using watchdog oscillator)
2. WDCON and WDL register can only be written once
3. WDRUN is forced to 1
Watchdog
oscillator
PCLK
÷32
÷2
÷32
÷64
÷2
÷128
÷2
÷256
÷2
÷512
÷2
÷1024
÷2
÷2048
÷2
÷4096
WDCLK after a
Watchdog feed
sequence
PRE2
PRE1
PRE0
DECODE
TO WATCHDOG
DOWN COUNTER
(after one prescaler
count delay)
000
001
010
011
100
101
110
111
002aaa938
Fig 48. Watchdog Prescaler.
16.2 Feed sequence
The watchdog timer control register and the 8-bit down counter (See Figure 49) are not
directly loaded by the user. The user writes to the WDCON and the WDL SFRs. At the end
of a feed sequence, the values in the WDCON and WDL SFRs are loaded to the control
register and the 8-bit down counter. Before the feed sequence, any new values written to
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these two SFRs will not take effect. To avoid a watchdog reset, the watchdog timer needs
to be fed (via a special sequence of software action called the feed sequence) prior to
reaching an underflow.
To feed the watchdog, two write instructions must be sequentially executed successfully.
Between the two write instructions, SFR reads are allowed, but writes are not allowed.
The instructions should move A5H to the WFEED1 register and then 5AH to the WFEED2
register. An incorrect feed sequence will cause an immediate watchdog reset. The
program sequence to feed the watchdog timer is as follows:
CLR EA ;disable interrupt
MOV WFEED1,#0A5h ;do watchdog feed part 1
MOV WFEED2,#05Ah ;do watchdog feed part 2
SETB EA ;enable interrupt
This sequence assumes that the P89LPC938 interrupt system is enabled and there is a
possibility of an interrupt request occurring during the feed sequence. If an interrupt was
allowed to be serviced and the service routine contained any SFR writes, it would trigger a
watchdog reset. If it is known that no interrupt could occur during the feed sequence, the
instructions to disable and re-enable interrupts may be removed.
In watchdog mode (WDTE = 1), writing the WDCON register must be IMMEDIATELY
followed by a feed sequence to load the WDL to the 8-bit down counter, and the WDCON
to the shadow register. If writing to the WDCON register is not immediately followed by the
feed sequence, a watchdog reset will occur.
For example: setting WDRUN = 1:
MOV ACC,WDCON ;get WDCON
SETB ACC.2 ;set WD_RUN=1
MOV WDL,#0FFh ;New count to be loaded to 8-bit down counter
CLR EA ;disable interrupt
MOV WDCON,ACC ;write back to WDCON (after the watchdog is enabled, a feed
must occur ; immediately)
MOV WFEED1,#0A5h ;do watchdog feed part 1
MOV WFEED2,#05Ah ;do watchdog feed part 2
SETB EA ;enable interrupt
In timer mode (WDTE = 0), WDCON is loaded to the control register every CCLK cycle
(no feed sequence is required to load the control register), but a feed sequence is required
to load from the WDL SFR to the 8-bit down counter before a time-out occurs.
The number of watchdog clocks before timing out is calculated by the following equations:
tclks = ( 2
( 5 + PRE )
) ( WDL + 1 ) + 1
(1)
where:
PRE is the value of prescaler (PRE2 to PRE0) which can be the range 0 to 7, and;
WDL is the value of watchdog load register which can be the range of 0 to 255.
The minimum number of tclks is:
tclks = ( 2
(5 + 0)
) ( 0 + 1 ) + 1 = 33
(2)
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The maximum number of tclks is:
tclks = ( 2
(5 + 7)
) ( 255 + 1 ) + 1 = 1048577
(3)
Table 104 shows sample P89LPC938 timeout values.
Table 102: Watchdog Timer Control register (WDCON - address A7h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
PRE2
PRE1
PRE0
-
-
WDRUN
WDTOF
WDCLK
Reset
1
1
1
x
x
1
1/0
1
Table 103: Watchdog Timer Control register (WDCON - address A7h) bit description
Bit Symbol
Description
0
WDCLK
Watchdog input clock select. When set, the watchdog oscillator is selected. When cleared, PCLK is
selected. (If the CPU is powered down, the watchdog is disabled if WDCLK = 0, see Section 16.5). (Note: If
both WDTE and WDSE are set to 1, this bit is forced to 1.) Refer to Section 16.3 for details.
1
WDTOF
Watchdog Timer Time-Out Flag. This bit is set when the 8-bit down counter underflows. In watchdog mode,
a feed sequence will clear this bit. It can also be cleared by writing a logic 0 to this bit in software.
2
WDRUN Watchdog Run Control. The watchdog timer is started when WDRUN = 1 and stopped when WDRUN = 0.
This bit is forced to 1 (watchdog running) and cannot be cleared to zero if both WDTE and WDSE are set to
1.
3:4 5
PRE0
6
PRE1
7
PRE2
reserved
Clock Prescaler Tap Select. Refer to Table 104 for details.
Table 104: Watchdog timeout vales
PRE2 to PRE0
000
001
010
011
100
101
WDL in decimal)
Timeout Period
Watchdog Clock Source
(in watchdog clock
cycles)
400 KHz Watchdog
Oscillator Clock
(Nominal)
0
33
82.5 µs
5.50 µs
255
8,193
20.5 ms
1.37 ms
0
65
162.5 µs
10.8 µs
255
16,385
41.0 ms
2.73 ms
0
129
322.5 µs
21.5 µs
255
32,769
81.9 ms
5.46 ms
0
257
642.5 µs
42.8 µs
255
65,537
163.8 ms
10.9 ms
0
513
1.28 ms
85.5 µs
255
131,073
327.7 ms
21.8 ms
0
1,025
2.56 ms
170.8 µs
255
262,145
655.4 ms
43.7 ms
12 MHz CCLK (6 MHz
CCLK⁄ Watchdog
2
Clock)
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Table 104: Watchdog timeout vales …continued
PRE2 to PRE0
110
111
WDL in decimal)
Timeout Period
Watchdog Clock Source
(in watchdog clock
cycles)
400 KHz Watchdog
Oscillator Clock
(Nominal)
12 MHz CCLK (6 MHz
CCLK⁄ Watchdog
2
Clock)
0
2,049
5.12 ms
341.5 µs
255
524,289
1.31 s
87.4 ms
0
4097
10.2 ms
682.8 µs
255
1,048,577
2.62 s
174.8 ms
16.3 Watchdog clock source
The watchdog timer system has an on-chip 400 KHz oscillator. The watchdog timer can
be clocked from either the watchdog oscillator or from PCLK (refer to Figure 48) by
configuring the WDCLK bit in the Watchdog Control Register WDCON. When the
watchdog feature is enabled, the timer must be fed regularly by software in order to
prevent it from resetting the CPU.
After changing WDCLK (WDCON.0), switching of the clock source will not immediately
take effect. As shown in Figure 50, the selection is loaded after a watchdog feed
sequence. In addition, due to clock synchronization logic, it can take two old clock cycles
before the old clock source is deselected, and then an additional two new clock cycles
before the new clock source is selected.
Since the prescaler starts counting immediately after a feed, switching clocks can cause
some inaccuracy in the prescaler count. The inaccuracy could be as much as 2 old clock
source counts plus 2 new clock cycles.
Note: When switching clocks, it is important that the old clock source is left enabled for
two clock cycles after the feed completes. Otherwise, the watchdog may become disabled
when the old clock source is disabled. For example, suppose PCLK (WCLK = 0) is the
current clock source. After WCLK is set to logic 1, the program should wait at least two
PCLK cycles (4 CCLKs) after the feed completes before going into Power-down mode.
Otherwise, the watchdog could become disabled when CCLK turns off. The watchdog
oscillator will never become selected as the clock source unless CCLK is turned on again
first.
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WDL (C1H)
MOV WFEED1, #0A5H
MOV WFEED2, #05AH
watchdog
oscillator
PCLK
÷32
8-BIT DOWN
COUNTER
PRESCALER
reset(1)
SHADOW REGISTER
WDCON (A7H)
PRE2
PRE1
PRE0
-
-
WDRUN
WDTOF
WDCLK
002aaa905
Fig 49. Watchdog Timer in Watchdog Mode (WDTE = 1).
16.4 Watchdog Timer in Timer mode
Figure 50 shows the Watchdog Timer in Timer Mode. In this mode, any changes to
WDCON are written to the shadow register after one watchdog clock cycle. A watchdog
underflow will set the WDTOF bit. If IEN0.6 is set, the watchdog underflow is enabled to
cause an interrupt. WDTOF is cleared by writing a logic 0 to this bit in software. When an
underflow occurs, the contents of WDL is reloaded into the down counter and the
watchdog timer immediately begins to count down again.
A feed is necessary to cause WDL to be loaded into the down counter before an underflow
occurs. Incorrect feeds are ignored in this mode.
WDL (C1H)
MOV WFEED1, #0A5H
MOV WFEED2, #05AH
watchdog
oscillator
PCLK
÷32
8-BIT DOWN
COUNTER
PRESCALER
interrupt
SHADOW REGISTER
WDCON (A7H)
PRE2
PRE1
PRE0
-
-
WDRUN
WDTOF
WDCLK
002aaa939
Fig 50. Watchdog Timer in Timer Mode (WDTE = 0).
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16.5 Power-down operation
The WDT oscillator will continue to run in power-down, consuming approximately 50 µA,
as long as the WDT oscillator is selected as the clock source for the WDT. Selecting PCLK
as the WDT source will result in the WDT oscillator going into power-down with the rest of
the device (see Section 16.3). Power-down mode will also prevent PCLK from running and
therefore the watchdog is effectively disabled.
16.6 Periodic wake-up from power-down without an external oscillator
Without using an external oscillator source, the power consumption required in order to
have a periodic wake-up is determined by the power consumption of the internal oscillator
source used to produce the wake-up. The Real-time clock running from the internal RC
oscillator can be used. The power consumption of this oscillator is approximately 300 µA.
Instead, if the WDT is used to generate interrupts the current is reduced to approximately
50 µA. Whenever the WDT underflows, the device will wake-up.
17. Additional features
The AUXR1 register contains several special purpose control bits that relate to several
chip features. AUXR1 is described in Table 106
Table 105: AUXR1 register (address A2h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
CLKLP
EBRR
ENT1
ENT0
SRST
0
-
DPS
Reset
0
0
0
0
0
0
x
0
Table 106: AUXR1 register (address A2h) bit description
Bit Symbol
Description
0
DPS
Data Pointer Select. Chooses one of two Data Pointers.
1
-
Not used. Allowable to set to a logic 1.
2
0
This bit contains a hard-wired 0. Allows toggling of the DPS bit by incrementing
AUXR1, without interfering with other bits in the register.
3
SRST
Software Reset. When set by software, resets the P89LPC938 as if a hardware
reset occurred.
4
ENT0
When set the P1.2 pin is toggled whenever Timer 0 overflows. The output
frequency is therefore one half of the Timer 0 overflow rate. Refer to Section 8
“Timers 0 and 1” for details.
5
ENT1
When set, the P0.7 pin is toggled whenever Timer 1 overflows. The output
frequency is therefore one half of the Timer 1 overflow rate. Refer to Section 8
“Timers 0 and 1” for details.
6
EBRR
UART Break Detect Reset Enable. If logic 1, UART Break Detect will cause a chip
reset and force the device into ISP mode.
7
CLKLP
Clock Low Power Select. When set, reduces power consumption in the clock
circuits. Can be used when the clock frequency is 8 MHz or less. After reset this bit
is cleared to support up to 12 MHz operation.
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17.1 Software reset
The SRST bit in AUXR1 gives software the opportunity to reset the processor completely,
as if an external reset or watchdog reset had occurred. If a value is written to AUXR1 that
contains a 1 at bit position 3, all SFRs will be initialized and execution will resume at
program address 0000. Care should be taken when writing to AUXR1 to avoid accidental
software resets.
17.2 Dual Data Pointers
The dual Data Pointers (DPTR) adds to the ways in which the processor can specify the
address used with certain instructions. The DPS bit in the AUXR1 register selects one of
the two Data Pointers. The DPTR that is not currently selected is not accessible to
software unless the DPS bit is toggled.
Specific instructions affected by the Data Pointer selection are:
INC DPTR — Increments the Data Pointer by 1
JMP@A+DPTR — Jump indirect relative to DPTR value
MOV DPTR, #data16 — Load the Data Pointer with a 16-bit constant
MOVC A, @A+DPTR — Move code byte relative to DPTR to the accumulator
MOVX A, @DPTR — Move accumulator to data memory relative to DPTR
MOVX @DPTR, A — Move from data memory relative to DPTR to the accumulator
Also, any instruction that reads or manipulates the DPH and DPL registers (the upper and
lower bytes of the current DPTR) will be affected by the setting of DPS. The MOVX
instructions have limited application for the P89LPC938 since the part does not have an
external data bus. However, they may be used to access Flash configuration information
(see Flash Configuration section) or auxiliary data (XDATA) memory.
Bit 2 of AUXR1 is permanently wired as a logic 0. This is so that the DPS bit may be
toggled (thereby switching Data Pointers) simply by incrementing the AUXR1 register,
without the possibility of inadvertently altering other bits in the register.
18. Data EEPROM
The P89LPC938 has 512 bytes of on-chip Data EEPROM that can be used to save
configuration parameters. The Data EEPROM is SFR based, byte readable, byte writable,
and erasable (via row fill and sector fill). The user can read, write, and fill the memory via
three SFRs and one interrupt:
• Address Register (DEEADR) is used for address bits 7 to 0 (bit 8 is in the DEECON
register).
• Control Register (DEECON) is used for address bit 8, setup operation mode, and
status flag bit (see Table 107).
• Data Register (DEEDAT) is used for writing data to, or reading data from, the Data
EEPROM.
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Table 107: Data EEPROM control register (DEECON address F1h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
EEIF
HVERR
ECTL1
ECTL0
-
-
-
EADR8
Reset
0
0
0
0
0
0
x
0
Table 108: Data EEPROM control register (DEECON address F1h) bit description
Bit Symbol
Description
0
Most significant address (bit 8) of the Data EEPROM. EADR7-0 are in DEEADR.
EADR8
1:3
Reserved.
5:4 ECTL1:0 Operation mode selection:
The following modes are selected by ECTL[1:0]:
00 — Byte read / write mode.
01 — Reserved.
10 — Row (64 bytes) fill.
11 — Block fill (512 bytes).
6
HVERR
High voltage error. Indicates a programming voltage error during program or erase.
7
EEIF
Data EEPROM interrupt flag. Set when a read or write finishes, reset by software.
Byte Mode: In this mode data can be read and written to one byte at a time. Data is in the
DEEDAT register and the address is in the DEEADR register. Each write requires
approximately 4 ms to complete. Each read requires three machines after writing the
address to the DEEADR register.
Row Fill: In this mode the addressed row (64 bytes, with address DEEADR[5:0] ignored) is
filled with the DEEDAT pattern. To erase the entire row to 00h or program the entire row to
FFh, write 00h or FFh to DEEDAT prior to row fill. Each row fill requires approximately
4 ms to complete.
Block Fill: In this mode all 512 bytes are filled with the DEEDAT pattern. To erase the block
to 00h or program the block to FFh, write 00h or FFh to DEEDAT prior to the block fill. Prior
to using this command EADR8 must be set = 1. Each Block Fill requires approximately
4 ms to complete.
In any mode, after the operation finishes, the hardware will set EEIF bit. An interrupt can
be enabled via the IEN1.7 bit. If IEN1.7 and the EA bits are set, it will generate an interrupt
request. The EEIF bit will need to be cleared by software.
18.1 Data EEPROM read
A byte can be read via polling or interrupt:
1. Write to DEECON with ECTL1/ECTL0 (DEECON[5:4]) = ‘00’ and correct bit 8 address
to EADR8. (Note that if the correct values are already written to DEECON, there is no
need to write to this register.)
2. Without writing to the DEEDAT register, write address bits 7 to 0 to DEEADR.
3. If both the EIEE (IEN1.7) bit and the EA (IEN0.7) bit are logic 1s, wait for the Data
EEPROM interrupt then read/poll the EEIF (DEECON.7) bit until it is set to logic 1. If
EIEE or EA is logic 0, the interrupt is disabled, only polling is enabled.
4. Read the Data EEPROM data from the DEEDAT SFR.
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Note that if DEEDAT is written prior to a write to DEEADR (if DEECON[5:4] = ‘00’), a Data
EEPROM write operation will commence. The user must take caution that such cases do
not occur during a read. An example is if the Data EEPROM is read in an interrupt service
routine with the interrupt occurring in the middle of a Data EEPROM cycle. The user
should disable interrupts during a Data EEPROM write operation (see Section 18.2).
18.2 Data EEPROM write
A byte can be written via polling or interrupt:
1. Write to DEECON with ECTL1/ECTL0 (DEECON[5:4]) = ‘00’ and correct bit 8 address
to EADR8. (Note that if the correct values are already written to DEECON, there is no
need to write to this register.)
2. Write the data to the DEEDAT register.
3. Write address bits 7 to 0 to DEEADR.
4. If both the EIEE (IEN1.7) bit and the EA (IEN0.7) bit are logic 1s, wait for the Data
EEPROM interrupt then read/poll the EEIF (DEECON.7) bit until it is set to logic 1. If
EIEE or EA is logic 0, the interrupt is disabled and only polling is enabled. When EEIF
is logic 1, the operation is complete and data is written.
As a write to the DEEDAT register followed by a write to the DEEADR register will
automatically set off a write (if DEECON[5:4] = ‘00’), the user must take great caution in a
write to the DEEDAT register. It is strongly recommended that the user disables interrupts
prior to a write to the DEEDAT register and enable interrupts after all writes are over. An
example is as follows:
CLR EA
MOV DEEDAT,@R0
MOV DEEADR,@R1
SETB EA
;disable interrupt
;write data pattern
;write address for the data
;wait for the interrupt orpoll the DEECON.7 (EEIF) bit
18.3 Hardware reset
During any hardware reset, including watchdog and system timer reset, the state machine
that ‘remembers’ a write to the DEEDAT register will be initialized. If a write to the
DEEDAT register occurs followed by a hardware reset, a write to the DEEADR register
without a prior write to the DEEDAT register will result in a read cycle.
18.4 Multiple writes to the DEEDAT register
If there are multiple writes to the DEEDAT register before a write to the DEEADR register,
the last data written to the DEEDAT register will be written to the corresponding address.
18.5 Sequences of writes to DEECON and DEEDAT registers
A write to the DEEDAT register is considered a valid write (i.e, will trigger the state
machine to ‘remember’ a write operation is to commence) if DEECON[5:4] = ‘00’. If these
mode bits are already ‘00’ and address bit 8 is correct, there is no need to write to the
DEECON register prior to a write to the DEEDAT register.
18.6 Data EEPROM Row Fill
A row (64 bytes) can be filled with a predetermined data pattern via polling or interrupt:
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1. Write to DEECON with ECTL1/ECTL0 (DEECON[5:4]) = ‘10’ and correct bit 8 address
to EADR8. (Note that if the correct values are already written to DEECON, there is no
need to write to this register.)
2. Write the fill pattern to the DEEDAT register. (Note that if the correct values are
already written to DEEDAT, there is no need to write to this register.)
3. Write address bits 7 to 0 to DEEADR. Note that address bits 5 to 0 are ignored.
4. If both the EIEE (IEN1.7) bit and the EA (IEN0.7) bit are logic 1s, wait for the Data
EEPROM interrupt then read/poll the EEIF (DEECON.7) bit until it is set to logic 1. If
EIEE or EA is logic 0, the interrupt is disabled and only polling is enabled. When EEIF
is logic 1, the operation is complete and row is filled with the DEEDAT pattern.
18.7 Data EEPROM Block Fill
The Data EEPROM array can be filled with a predetermined data pattern via polling or
interrupt:
1. Write to DEECON with ECTL1/ECTL0 (DEECON[5:4]) = ‘11’. Set bit EADR8 = 1.
2. Write the fill pattern to the DEEDAT register.
3. Write any address to DEEADR. Note that the entire address is ignored in a block fill
operation.
4. If both the EIEE (IEN1.7) bit and the EA (IEN0.7) bit are logic 1s, wait for the Data
EEPROM interrupt then read/poll the EEIF (DEECON.7) bit until it is set to logic 1. If
EIEE or EA is logic 0, the interrupt is disabled and only polling is enabled. When EEIF
is logic 1, the operation is complete.
19. Flash memory
19.1 General description
The P89LPC938 Flash memory provides in-circuit electrical erasure and programming.
The Flash can be read and written as bytes. The Sector and Page Erase functions can
erase any Flash sector (1 kB) or page (64 bytes). The Chip Erase operation will erase the
entire program memory. Five Flash programming methods are available. On-chip erase
and write timing generation contribute to a user-friendly programming interface. The
P89LPC938 Flash reliably stores memory contents even after 100,000 erase and program
cycles. The cell is designed to optimize the erase and programming mechanisms.
P89LPC938 uses VDD as the supply voltage to perform the Program/Erase algorithms
19.2 Features
• Parallel programming with industry-standard commercial programmers
• In-Circuit serial Programming (ICP) with industry-standard commercial programmers.
• IAP-Lite allows individual and multiple bytes of code memory to be used for data
storage and programmed under control of the end application.
• Internal fixed boot ROM, containing low-level In-Application Programming (IAP)
routines that can be called from the end application (in addition to IAP-Lite).
• Default serial loader providing In-System Programming (ISP) via the serial port,
located in upper end of user program memory.
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• Boot vector allows user provided Flash loader code to reside anywhere in the Flash
memory space, providing flexibility to the user.
•
•
•
•
•
•
Programming and erase over the full operating voltage range
Read/Programming/Erase using ISP/IAP/IAP-Lite
Any flash program operation in 2 ms (4 ms for erase/program)
Programmable security for the code in the Flash for each sector
> 100,000 typical erase/program cycles for each byte
10-year minimum data retention
19.3 Flash programming and erase
The P89LPC938 program memory consists 1 kB sectors. Each sector can be further
divided into 64-byte pages. In addition to sector erase and page erase, a 64-byte page
register is included which allows from 1 to 64 bytes of a given page to be programmed at
the same time, substantially reducing overall programming time. Five methods of
programming this device are available.
• Parallel programming with industry-standard commercial programmers.
• In-Circuit serial Programming (ICP) with industry-standard commercial programmers.
• IAP-Lite allows individual and multiple bytes of code memory to be used for data
storage and programmed under control of the end application.
• Internal fixed boot ROM, containing low-level In-Application Programming (IAP)
routines that can be called from the end application (in addition to IAP-Lite).
• A factory-provided default serial loader, located in upper end of user program
memory, providing In-System Programming (ISP) via the serial port.
19.4 Using Flash as data storage: IAP-Lite
The Flash code memory array of this device supports IAP-Lite in addition to standard IAP
functions. Any byte in a non-secured sector of the code memory array may be read using
the MOVC instruction and thus is suitable for use as non-volatile data storage. IAP-Lite
provides an erase-program function that makes it easy for one or more bytes within a
page to be erased and programmed in a single operation without the need to erase or
program any other bytes in the page. IAP-Lite is performed in the application under the
control of the microcontroller’s firmware using four SFRs and an internal 64-byte ‘page
register’ to facilitate erasing and programing within unsecured sectors. These SFRs are:
• FMCON (Flash Control Register). When read, this is the status register. When written,
this is a command register. Note that the status bits are cleared to logic 0s when the
command is written.
• FMADRL, FMADRH (Flash memory address low, Flash memory address high). Used
to specify the byte address within the page register or specify the page within user
code memory
• FMDATA (Flash Data Register). Accepts data to be loaded into the page register.
The page register consists of 64 bytes and an update flag for each byte. When a LOAD
command is issued to FMCON the page register contents and all of the update flags will
be cleared. When FMDATA is written, the value written to FMDATA will be stored in the
page register at the location specified by the lower 6 bits of FMADRL. In addition, the
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update flag for that location will be set. FMADRL will auto-increment to the next location.
Auto-increment after writing to the last byte in the page register will ‘wrap-around’ to the
first byte in the page register, but will not affect FMADRL[7:6]. Bytes loaded into the page
register do not have to be continuous. Any byte location can be loaded into the page
register by changing the contents of FMADRL prior to writing to FMDATA. However, each
location in the page register can only be written once following each LOAD command.
Attempts to write to a page register location more than once should be avoided.
FMADRH and FMADRL[7:6] are used to select a page of code memory for the
erase-program function. When the erase-program command is written to FMCON, the
locations within the code memory page that correspond to updated locations in the page
register, will have their contents erased and programmed with the contents of their
corresponding locations in the page register. Only the bytes that were loaded into the
page register will be erased and programmed in the user code array. Other bytes within
the user code memory will not be affected.
Writing the erase-program command (68H) to FMCON will start the erase-program
process and place the CPU in a program-idle state. The CPU will remain in this idle state
until the erase-program cycle is either completed or terminated by an interrupt. When the
program-idle state is exited FMCON will contain status information for the cycle.
If an interrupt occurs during an erase/programming cycle, the erase/programming cycle
will be aborted and the OI flag (Operation Interrupted) in FMCON will be set. If the
application permits interrupts during erasing-programming the user code should check the
OI flag (FMCON.0) after each erase-programming operation to see if the operation was
aborted. If the operation was aborted, the user’s code will need to repeat the process
starting with loading the page register.
The erase-program cycle takes 4 ms (2 ms for erase, 2 ms for programming) to complete,
regardless of the number of bytes that were loaded into the page register.
Erasing-programming of a single byte (or multiple bytes) in code memory is accomplished
using the following steps:
• Write the LOAD command (00H) to FMCON. The LOAD command will clear all
locations in the page register and their corresponding update flags.
• Write the address within the page register to FMADRL. Since the loading the page
register uses FMADRL[5:0], and since the erase-program command uses FMADRH
and FMADRL[7:6], the user can write the byte location within the page register
(FMADRL[5:0]) and the code memory page address (FMADRH and FMADRL[7:6]) at
this time.
• Write the data to be programmed to FMDATA. This will increment FMADRL pointing to
the next byte in the page register.
• Write the address of the next byte to be programmed to FMADRL, if desired. (Not
needed for contiguous bytes since FMADRL is auto-incremented). All bytes to be
programmed must be within the same page.
• Write the data for the next byte to be programmed to FMDATA.
• Repeat writing of FMADRL and/or FMDATA until all desired bytes have been loaded
into the page register.
• Write the page address in user code memory to FMADRH and FMADRL[7:6], if not
previously included when writing the page register address to FMADRL[5:0].
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• Write the erase-program command (68H) to FMCON, starting the erase-program
cycle.
• Read FMCON to check status. If aborted, repeat starting with the LOAD command.
Table 109: Flash Memory Control register (FMCON - address E4h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol (R) -
-
-
-
HVA
HVE
SV
OI
Symbol (W) FMCMD.7
FMCMD.6
FMCMD.5
FMCMD.4
FMCMD.3
FMCMD.2
FMCMD.1
FMCMD.0
Reset
0
0
0
0
0
0
0
0
Table 110: Flash Memory Control register (FMCON - address E4h) bit description
Bit
0
Symbol
Access
Description
OI
R
Operation interrupted. Set when cycle aborted due to an interrupt or reset.
FMCMD.0
W
Command byte bit 0.
SV
R
Security violation. Set when an attempt is made to program, erase, or CRC a secured sector or
page.
FMCMD.1
W
Command byte bit 1
HVE
R
High voltage error. Set when an error occurs in the high voltage generator.
FMCMD.2
W
Command byte bit 2.
HVA
R
High voltage abort. Set if either an interrupt or a brown-out is detected during a program or
erase cycle. Also set if the brown-out detector is disabled at the start of a program or erase
cycle.
FMCMD.3
W
Command byte bit 3.
4:7
-
R
reserved
4:7
FMCMD.4
W
Command byte bit 4.
4:7
FMCMD.5
W
Command byte bit 5.
4:7
FMCMD.6
W
Command byte bit 6.
4:7
FMCMD.7
W
Command byte bit 7.
1
2
3
An assembly language routine to load the page register and perform an erase/program
operation is shown below.
;**************************************************
;* pgm user code *
;**************************************************
;*
*
;* Inputs:
*
;* R3 = number of bytes to program (byte)
*
;* R4 = page address MSB(byte)
*
;* R5 = page address LSB(byte)
*
;* R7 = pointer to data buffer in RAM(byte)
*
;* Outputs:
*
;* R7 = status (byte)
*
;* C = clear on no error, set on error
*
;**************************************************
LOAD
EP
EQU
EQU
00H
68H
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PGM_USER:
MOV
FMCON,#LOAD
MOV
FMADRH,R4
MOV
FMADRL,R5
MOV
A,R7
MOV
R0,A
LOAD_PAGE:
MOV
FMDAT,@R0
INC
R0
DJNZ
R3,LOAD_PAGE
MOV
FMCON,#EP
;load command, clears page register
;get high address
;get low address
;
;get pointer into R0
;write data to page register
;point to next byte
;do until count is zero
;else erase & program the page
MOV
MOV
ANL
JNZ
CLR
RET
R7,FMCON
A,R7
A,#0FH
BAD
C
;copy status for return
;read status
;save only four lower bits
;
;clear error flag if good
;and return
SETB
RET
C
;set error flag
;and return
BAD:
A C-language routine to load the page register and perform an erase/program operation is
shown below.
#include <REG938.H>
unsigned char idata dbytes[64]; // data buffer
unsigned char Fm_stat; // status result
bit PGM_USER (unsigned char, unsigned char);
bit prog_fail;
void main ()
{
prog_fail=PGM_USER(0x1F,0xC0);
}
bit PGM_USER (unsigned char page_hi, unsigned char page_lo)
{
#define LOAD 0x00 // clear page register, enable loading
#define EP 0x68 // erase & program page
unsigned char i; // loop count
FMCON = LOAD; //load command, clears page reg
FMADRH = page_hi; //
FMADRL = page_lo; //write my page address to addr regs
for (i=0;i<64;i=i+1)
{
FMDATA = dbytes[i];
}
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FMCON = EP; //erase & prog page command
Fm_stat = FMCON; //read the result status
if ((Fm_stat & 0x0F)!=0) prog_fail=1; else prog_fail=0;
return(prog_fail);
}
19.5 In-circuit programming (ICP)
In-Circuit Programming is a method intended to allow commercial programmers to
program and erase these devices without removing the microcontroller from the system.
The In-Circuit Programming facility consists of a series of internal hardware resources to
facilitate remote programming of the P89LPC938 through a two-wire serial interface.
Philips has made in-circuit programming in an embedded application possible with a
minimum of additional expense in components and circuit board area. The ICP function
uses five pins (VDD, VSS, P0.5, P0.4, and RST). Only a small connector needs to be
available to interface your application to an external programmer in order to use this
feature.
19.6 ISP and IAP capabilities of the P89LPC938
An In-Application Programming (IAP) interface is provided to allow the end user’s
application to erase and reprogram the user code memory. In addition, erasing and
reprogramming of user-programmable bytes including UCFG1, the Boot Status Bit, and
the Boot Vector is supported. As shipped from the factory, the upper 512 bytes of user
code space contains a serial In-System Programming (ISP) loader allowing for the device
to be programmed in circuit through the serial port. This ISP boot loader will, in turn, call
low-level routines through the same common entry point that can be used by the end-user
application.
19.7 Boot ROM
When the microcontroller contains a a 256 byte Boot ROM that is separate from the user’s
Flash program memory. This Boot ROM contains routines which handle all of the low level
details needed to erase and program the user Flash memory. A user program simply calls
a common entry point in the Boot ROM with appropriate parameters to accomplish the
desired operation. Boot ROM operations include operations such as erase sector, erase
page, program page, CRC, program security bit, etc. The Boot ROM occupies the
program memory space at the top of the address space from FF00 to FFFFh, thereby not
conflicting with the user program memory space. This function is in addition to the IAP-Lite
feature.
19.8 Power on reset code execution
The P89LPC938 contains two special Flash elements: the BOOT VECTOR and the Boot
Status Bit. Following reset, the P89LPC938 examines the contents of the Boot Status Bit.
If the Boot Status Bit is set to zero, power-up execution starts at location 0000H, which is
the normal start address of the user’s application code. When the Boot Status Bit is set to
a va one, the contents of the Boot Vector is used as the high byte of the execution address
and the low byte is set to 00H.
The factory default settings for this device is shown in Table 111, below.
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The factory pre-programmed boot loader can be erased by the user. Users who wish to
use this loader should take cautions to avoid erasing the last 1 kB sector on the device.
Instead, the page erase function can be used to erase the eight 64-byte pages located in
this sector. A custom boot loader can be written with the Boot Vector set to the custom
boot loader, if desired.
Table 111: Boot loader address and default Boot vector
Product
P89LPC938
Flash size End
address
Signature bytes
Mfg id Id 1
8 kB × 8
15h
1FFFh
DDh
Id 2
Sector
size
Page
size
Pre-programmed
serial loader
Default Boot
vector
25h
1 kB × 8
64 × 8
1E00h to 1FFFh
1Fh
19.9 Hardware activation of Boot Loader
The boot loader can also be executed by forcing the device into ISP mode during a
power-on sequence (see Figure 51). This is accomplished by powering up the device with
the reset pin initially held low and holding the pin low for a fixed time after VDD rises to its
normal operating value. This is followed by three, and only three, properly timed low-going
pulses. Fewer or more than three pulses will result in the device not entering ISP mode.
Timing specifications may be found in the data sheet for this device.
This has the same effect as having a non-zero status bit. This allows an application to be
built that will normally execute the user code but can be manually forced into ISP
operation. If the factory default setting for the Boot Vector is changed, it will no longer point
to the factory pre-programmed ISP boot loader code. If this happens, the only way it is
possible to change the contents of the Boot Vector is through the parallel or ICP
programming method, provided that the end user application does not contain a
customized loader that provides for erasing and reprogramming of the Boot Vector and
Boot Status Bit. After programming the Flash, the status byte should be programmed to
zero in order to allow execution of the user’s application code beginning at address
0000H.
VDD
tVR
tRH
RST
tRL
002aaa912
Fig 51. Forcing ISP mode.
19.10 In-system programming (ISP)
In-System Programming is performed without removing the microcontroller from the
system. The In-System Programming facility consists of a series of internal hardware
resources coupled with internal firmware to facilitate remote programming of the
P89LPC938 through the serial port. This firmware is provided by Philips and embedded
within each P89LPC938 device. The Philips In-System Programming facility has made
in-circuit programming in an embedded application possible with a minimum of additional
expense in components and circuit board area. The ISP function uses five pins (VDD, VSS,
TXD, RXD, and RST). Only a small connector needs to be available to interface your
application to an external circuit in order to use this feature.
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19.11 Using the In-system programming (ISP)
The ISP feature allows for a wide range of baud rates to be used in your application,
independent of the oscillator frequency. It is also adaptable to a wide range of oscillator
frequencies. This is accomplished by measuring the bit-time of a single bit in a received
character. This information is then used to program the baud rate in terms of timer counts
based on the oscillator frequency. The ISP feature requires that an initial character (an
uppercase U) be sent to the P89LPC938 to establish the baud rate. The ISP firmware
provides auto-echo of received characters. Once baud rate initialization has been
performed, the ISP firmware will only accept Intel Hex-type records. Intel Hex records
consist of ASCII characters used to represent hexadecimal values and are summarized
below:
:NNAAAARRDD..DDCC<crlf>
In the Intel Hex record, the ‘NN’ represents the number of data bytes in the record. The
P89LPC938 will accept up to 64 (40H) data bytes. The ‘AAAA’ string represents the
address of the first byte in the record. If there are zero bytes in the record, this field is often
set to 0000. The ‘RR’ string indicates the record type. A record type of ‘00’ is a data
record. A record type of ‘01’ indicates the end-of-file mark. In this application, additional
record types will be added to indicate either commands or data for the ISP facility. The
maximum number of data bytes in a record is limited to 64 (decimal). ISP commands are
summarized in Table 112. As a record is received by the P89LPC938, the information in
the record is stored internally and a checksum calculation is performed. The operation
indicated by the record type is not performed until the entire record has been received.
Should an error occur in the checksum, the P89LPC938 will send an ‘X’ out the serial port
indicating a checksum error. If the checksum calculation is found to match the checksum
in the record, then the command will be executed. In most cases, successful reception of
the record will be indicated by transmitting a ‘.’ character out the serial port.
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Table 112: In-system Programming (ISP) hex record formats
Record type
00
Command/data function
Program User Code Memory Page
:nnaaaa00dd..ddcc
Where:
nn = number of bytes to program
aaaa = page address
dd..dd= data bytes
cc = checksum
Example:
:100000000102030405006070809cc
01
Read Version Id
:00xxxx01cc
Where:
xxxx = required field but value is a ‘don’t care’
cc = checksum
Example:
:00000001cc
02
Miscellaneous Write Functions
:02xxxx02ssddcc
Where:
xxxx = required field but value is a ‘don’t care’
ss= subfunction code
dd= data
cc = checksum
Subfunction codes:
00= UCFG1
01= reserved
02= Boot Vector
03= Status Byte
04= reserved
05= reserved
06= reserved
07= reserved
08= Security Byte 0
09= Security Byte 1
0A= Security Byte 2
0B= Security Byte 3
0C= Security Byte 4
0D= Security Byte 5
0E= Security Byte 6
0F= Security Byte 7
10= Clear Configuration Protection
Example:
:020000020347cc
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Table 112: In-system Programming (ISP) hex record formats …continued
Record type
Command/data function
03
Miscellaneous Read Functions
:01xxxx03sscc
Where
xxxx = required field but value is a ‘don’t care’
ss= subfunction code
cc = checksum
Subfunction codes:
00= UCFG1
01= reserved
02= Boot Vector
03= Status Byte
04= reserved
05= reserved
06= reserved
07= reserved
08= Security Byte 0
09= Security Byte 1
0A= Security Byte 2
0B= Security Byte 3
0C= Security Byte 4
0D= Security Byte 5
0E= Security Byte 6
0F= Security Byte 7
10= Manufacturer Id
11= Device Id
12= Derivative Id
Example:
:0100000312cc
04
Erase Sector/Page
:03xxxx04ssaaaacc
Where:
xxxx = required field but value is a ‘don’t care’
aaaa = sector/page address
ss= 01 erase sector
= 00 erase page
cc = checksum
Example:
:03000004010000F8
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Table 112: In-system Programming (ISP) hex record formats …continued
Record type
Command/data function
05
Read Sector CRC
:01xxxx05aacc
Where:
xxxx = required field but value is a ‘don’t care’
aa= sector address high byte
cc= checksum
Example:
:0100000504F6cc
06
Read Global CRC
:00xxxx06cc
Where:
xxxx = required field but value is a ‘don’t care’
cc= checksum
Example:
:00000006FA
07
Direct Load of Baud Rate
:02xxxx07HHLLcc
Where:
xxxx = required field but value is a ‘don’t care’
HH= high byte of timer
LL = low byte of timer
cc = checksum
Example:
:02000007FFFFcc
08
Reset MCU
:00xxxx08cc
Where:
xxxx = required field but value is a ‘don’t care’
cc = checksum
Example:
:00000008F8
19.12 In-application programming (IAP)
Several In-Application Programming (IAP) calls are available for use by an application
program to permit selective erasing and programming of Flash sectors, pages, security
bits, configuration bytes, and device id. All calls are made through a common interface,
PGM_MTP. The programming functions are selected by setting up the microcontroller’s
registers before making a call to PGM_MTP at FF03H. The IAP calls are shown in
Table 114.
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19.13 IAP authorization key
IAP functions which write or erase code memory require an authorization key be set by
the calling routine prior to performing the IAP function call. This authorization key is set by
writing 96H to RAM location FFH. The following example was written using the Keil C
compiler. The methods used to access a specific physical address in memory may vary
with other compilers.
#include <ABSACC.H> /* enable absolute memory access */
#define key DBYTE[0xFF] /* force key to be at address 0xFF */
short (*pgm_mtp) (void) = 0xFF00; /* set pointer to IAP entry point */;
key = 0x96; /* set the authorization key */
pgm_mtp (); /* execute the IAP function call */
After the function call is processed by the IAP routine, the authorization key will be
cleared. Thus it is necessary for the authorization key to be set prior to EACH call to
PGM_MTP that requires a key. If an IAP routine that requires an authorization key is
called without a valid authorization key present, the MCU will perform a reset.
19.14 Flash write enable
This device has hardware write enable protection. This protection applies to both ISP and
IAP modes and applies to both the user code memory space and the user configuration
bytes (UCFG1, BOOTVEC, and BOOTSTAT). This protection does not apply to ICP or
parallel programmer modes. If the Activate Write Enable (AWE) bit in BOOTSTAT.7 is a
logic 0, an internal Write Enable (WE) flag is forced set and writes to the flash memory
and configuration bytes are enabled. If the Active Write Enable (AWE) bit is a logic 1, then
the state of the internal WE flag can be controlled by the user.
The WE flag is SET by writing the Set Write Enable (08H) command to FMCON followed
by a key value (96H) to FMDATA:
FMCON = 0x08;
FMDATA = 0x96;
The WE flag is CLEARED by writing the Clear Write Enable (0BH) command to FMCON
followed by a key value (96H) to FMDATA, or by a reset:
FMCON = 0x0B;
FMDATA = 0x96;
The ISP function in this device sets the WE flag prior to calling the IAP routines. The IAP
function in this device executes a Clear Write Enable command following any write
operation. If the Write Enable function is active, user code which calls IAP routines will
need to set the Write Enable flag prior to each IAP write function call.
19.15 Configuration byte protection
In addition to the hardware write enable protection, described above, the ‘configuration
bytes’ may be separately write protected. These configuration bytes include UCFG1,
BOOTVEC, and BOOTSTAT. This protection applies to both ISP and IAP modes and does
not apply to ICP or parallel programmer modes.
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If the Configuration Write Protect bit (CWP) in BOOTSTAT.6 is a logic 1, writes to the
configuration bytes are disabled. If the Configuration Write Protect bit (CWP) is a logic 0,
writes to the configuration bytes are enabled. The CWP bit is set by programming the
BOOTSTAT register. This bit is cleared by using the Clear Configuration Protection (CCP)
command in IAP or ISP.
The Clear Configuration Protection command can be disabled in ISP or IAP mode by
programming the Disable Clear Configuration Protection bit (DCCP) in BOOTSTAT.7 to a
logic 1. When DCCP is set, the CCP command may still be used in ICP or parallel
programming modes. This bit is cleared by writing the Clear Configuration Protection
(CCP) command in either ICP or parallel programming modes.
19.16 IAP error status
It is not possible to use the Flash memory as the source of program instructions while
programming or erasing this same Flash memory. During an IAP erase, program, or CRC
the CPU enters a program-idle state. The CPU will remain in this program-idle state until
the erase, program, or CRC cycle is completed. These cycles are self timed. When the
cycle is completed, code execution resumes. If an interrupt occurs during an erase,
programming or CRC cycle, the erase, programming, or CRC cycle will be aborted so that
the Flash memory can be used as the source of instructions to service the interrupt. An
IAP error condition will be flagged by setting the carry flag and status information
returned. The status information returned is shown in Table 113. If the application permits
interrupts during erasing, programming, or CRC cycles, the user code should check the
carry flag after each erase, programming, or CRC operation to see if an error occurred. If
the operation was aborted, the user’s code will need to repeat the operation.
Table 113: IAP error status
Bit
Flag
Description
0
OI
Operation Interrupted. Indicates that an operation was aborted due to an interrupt occurring during a
program or erase cycle.
1
SV
Security Violation. Set if program or erase operation fails due to security settings. Cycle is aborted. Memory
contents are unchanged. CRC output is invalid.
2
HVE
High Voltage Error. Set if error detected in high voltage generation circuits. Cycle is aborted. Memory
contents may be corrupted.
3
VE
Verify error. Set during IAP programming of user code if the contents of the programmed address does not
agree with the intended programmed value. IAP uses the MOVC instruction to perform this verify. Attempts
to program user code that is MOVC protected can be programmed but will generate this error after the
programming cycle has been completed.
4 to 7
-
unused; reads as a logic 0
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Table 114: IAP function calls
IAP function
IAP call parameters
Program User Code Page (requires
‘key’)
Input parameters:
ACC = 00h
R3= number of bytes to program
R4= page address (MSB)
R5= page address (LSB)
R7= pointer to data buffer in RAM
F1= 0h = use IDATA
Return parameter(s):
R7= status
Carry= set on error, clear on no error
Read Version Id
Input parameters:
ACC = 01h
Return parameter(s):
R7= IAP code version id
Misc. Write (requires ‘key’)
Input parameters:
ACC = 02h
R5= data to write
R7= register address
00= UCFG1
01= reserved
02= Boot Vector
03= Status Byte
04= reserved
05= reserved
06= reserved
07= reserved
08= Security Byte 0
09= Security Byte 1
0A= Security Byte 2
0B= Security Byte 3
0C= Security Byte 4
0D= Security Byte 5
0E= Security Byte 6
0F= Security Byte 7
10 = Clear Configuration Protection
Return parameter(s):
R7= status
Carry= set on error, clear on no error
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Table 114: IAP function calls …continued
IAP function
IAP call parameters
Misc. Read
Input parameters:
ACC = 03h
R7= register address
00= UCFG1
01= reserved
02= Boot Vector
03= Status Byte
04= reserved
05= reserved
06= reserved
07= reserved
08= Security Byte 0
09= Security Byte 1
0A= Security Byte 2
0B= Security Byte 3
0C= Security Byte 4
0D= Security Byte 5
0E= Security Byte 6
0F= Security Byte 7
Return parameter(s):
R7= register data if no error, else error status
Carry= set on error, clear on no error
Erase Sector/Page (requires ‘key’)
Input parameters:
ACC = 04h
R7= 00H (erase page) or 01H (erase sector)
R4= sector/page address (MSB)
R5=sector/page address (LSB)
Return parameter(s):
R7= status
Carry= set on error, clear on no error
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Table 114: IAP function calls …continued
IAP function
IAP call parameters
Read Sector CRC
Input parameters:
ACC = 05h
R7= sector address
Return parameter(s):
R4= CRC bits 31:24
R5= CRC bits 23:16
R6= CRC bits 15:8
R7= CRC bits 7:0 (if no error)
R7= error status (if error)
Carry= set on error, clear on no error
Read Global CRC
Input parameters:
ACC = 06h
Return parameter(s):
R4= CRC bits 31:24
R5= CRC bits 23:16
R6= CRC bits 15:8
R7= CRC bits 7:0 (if no error)
R7= error status (if error)
Carry= set on error, clear on no error
Read User Code
Input parameters:
ACC = 07h
R4= address (MSB)
R5= address (LSB)
Return parameter(s):
R7= data
19.17 User configuration bytes
A number of user-configurable features of the P89LPC938 must be defined at power-up
and therefore cannot be set by the program after start of execution. These features are
configured through the use of an Flash byte UCFG1 shown in Table 116
Table 115: Flash User Configuration Byte (UCFG1) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
WDTE
RPE
BOE
WDSE
-
FOSC2
FOSC1
FOSC0
Unprogrammed
value
0
1
1
0
0
0
1
1
Table 116: Flash User Configuration Byte (UCFG1) bit description
Bit Symbol
Description
0
FOSC0
1
FOSC1
CPU oscillator type select. See Section 2 “Clocks” for additional information. Combinations other than those
shown in Table 117 are reserved for future use should not be used.
2
FOSC2
3
-
reserved
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Table 116: Flash User Configuration Byte (UCFG1) bit description …continued
Bit Symbol
Description
4
WDSE
Watchdog Safety Enable bit. Refer to Table 101 “Watchdog timer configuration” for details.
5
BOE
Brownout Detect Enable (see Section 6.1 “Brownout detection”)
6
RPE
Reset pin enable. When set = 1, enables the reset function of pin P1.5. When cleared, P1.5 may be used as
an input pin. NOTE: During a power-up sequence, the RPE selection is overridden and this pin will always
functions as a reset input. After power-up the pin will function as defined by the RPE bit. Only a power-up
reset will temporarily override the selection defined by RPE bit. Other sources of reset will not override the
RPE bit.
7
WDTE
Watchdog timer reset enable. When set = 1, enables the watchdog timer reset. When cleared = 0, disables
the watchdog timer reset. The timer may still be used to generate an interrupt. Refer to Table 101 “Watchdog
timer configuration” for details.
Table 117: Oscillator type selection
FOSC[2:0] Oscillator configuration
111
External clock input on XTAL1.
100
Watchdog Oscillator, 400 kHz (+20/ −30 % tolerance).
011
Internal RC oscillator, 7.373 MHz ± 2.5 %.
010
Low frequency crystal, 20 kHz to 100 kHz.
001
Medium frequency crystal or resonator, 100 kHz to 4 MHz.
000
High frequency crystal or resonator, 4 MHz to 18 MHz.
19.18 User security bytes
This device has three security bits associated with each of its eight sectors, as shown in
Table 118
Table 118: Sector Security Bytes (SECx) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
-
-
-
EDISx
SPEDISx
MOVCDISx
Unprogrammed
value
0
0
0
0
0
0
0
0
Table 119: Sector Security Bytes (SECx) bit description
Bit Symbol
Description
0
MOVCDISx
MOVC Disable. Disables the MOVC command for sector x. Any MOVC that attempts to read a byte in a
MOVC protected sector will return invalid data. This bit can only be erased when sector x is erased.
1
SPEDISx
Sector Program Erase Disable x. Disables program or erase of all or part of sector x. This bit and sector
x are erased by either a sector erase command (ISP, IAP, commercial programmer) or a 'global' erase
command (commercial programmer).
2
EDISx
Erase Disable ISP. Disables the ability to perform an erase of sector x in ISP or IAP mode. When
programmed, this bit and sector x can only be erased by a 'global' erase command using a commercial
programmer. This bit and sector x CANNOT be erased in ISP or IAP modes.
3:7 -
reserved
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Table 120: Effects of Security Bits
EDISx
SPEDISx
MOVCDISx
Effects on Programming
0
0
0
None.
0
0
1
Security violation flag set for sector CRC calculation for the specific sector.
Security violation flag set for global CRC calculation if any MOVCDISx bit is set.
Cycle aborted. Memory contents unchanged. CRC invalid. Program/erase
commands will not result in a security violation.
0
1
x
Security violation flag set for program commands or an erase page command.
Cycle aborted. Memory contents unchanged. Sector erase and global erase are
allowed.
1
x
x
Security violation flag set for program commands or an erase page command.
Cycle aborted. Memory contents unchanged. Global erase is allowed.
19.19 Boot Vector register
Table 121: Boot Vector (BOOTVEC) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
-
BOOTV4
BOOTV3
BOOTV2
BOOTV1
BOOTV0
Factory default
value
0
0
0
1
1
1
1
1
Table 122: Boot Vector (BOOTVEC) bit description
Bit Symbol
Description
0:4 BOOTV[0:4]
Boot vector. If the Boot Vector is selected as the reset address, the P89LPC938 will start execution at an
address comprised of 00h in the lower eight bits and this BOOTVEC as the upper eight bits after a reset.
5:7 -
reserved
19.20 Boot status register
Table 123: Boot Status (BOOTSTAT) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
DCCP
CWP
AWP
-
-
-
--
BSB
Factory default
value
0
0
0
0
0
0
0
1
Table 124: Boot Status (BOOTSTAT) bit description
Bit Symbol
Description
0
Boot Status Bit. If programmed to logic 1, the P89LPC938 will always start execution at an address
comprised of 00H in the lower eight bits and BOOTVEC as the upper bits after a reset. (See Section 7.1
“Reset vector”).
BSB
1:4 -
reserved
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Table 124: Boot Status (BOOTSTAT) bit description …continued
Bit Symbol
Description
5
AWP
Activate Write Protection bit. When this bit is cleared, the internal Write Enable flag is forced to the set
state, thus writes to the flash memory are always enabled. When this bit is set, the Write Enable internal
flag can be set or cleared using the Set Write Enable (SWE) or Clear Write Enable (CWE) commands.
6
CWP
Configuration Write Protect bit. Protects inadvertent writes to the user programmable configuration
bytes (UCFG1, BOOTVEC, and BOOTSTAT). If programmed to a logic 1, the writes to these registers
are disabled. If programmed to a logic 0, writes to these registers are enabled.
This bit is set by programming the BOOTSTAT register. This bit is cleared by writing the Clear
Configuration Protection (CCP) command to FMCON followed by writing 96H to FMDATA.
7
DCCP
Disable Clear Configuration Protection command. If Programmed to ‘1’, the Clear Configuration
Protection (CCP) command is disabled during ISP or IAP modes. This command can still be used in
ICP or parallel programmer modes. If programmed to ‘0’, the CCP command can be used in all
programming modes. This bit is set by programming the BOOTSTAT register. This bit is cleared by
writing the Clear Configuration Protection (CCP) command in either ICP or parallel programmer modes.
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20. Instruction set
Table 125: Instruction set summary
Mnemonic
Description
Bytes
Cycles
Hex code
ARITHMETIC
ADD A,Rn
Add register to A
1
1
28 to 2F
ADD A,dir
Add direct byte to A
2
1
25
ADD A,@Ri
Add indirect memory to A
1
1
26 to 27
ADD A,#data
Add immediate to A
2
1
24
ADDC A,Rn
Add register to A with carry
1
1
38 to 3F
ADDC A,dir
Add direct byte to A with carry
2
1
35
ADDC A,@Ri
Add indirect memory to A with carry
1
1
36 to 37
ADDC A,#data
Add immediate to A with carry
2
1
34
SUBB A,Rn
Subtract register from A with borrow
1
1
98 to 9F
SUBB A,dir
Subtract direct byte from A with borrow
2
1
95
SUBB A,@Ri
Subtract indirect memory from A with
borrow
1
1
96 to 97
SUBB A,#data
Subtract immediate from A with borrow
2
1
94
INC A
Increment A
1
1
04
INC Rn
Increment register
1
1
08 to 0F
INC dir
Increment direct byte
2
1
05
INC @Ri
Increment indirect memory
1
1
06 to 07
DEC A
Decrement A
1
1
14
DEC Rn
Decrement register
1
1
18 to 1F
DEC dir
Decrement direct byte
2
1
15
DEC @Ri
Decrement indirect memory
1
1
16 to 17
INC DPTR
Increment data pointer
1
2
A3
MUL AB
Multiply A by B
1
4
A4
DIV AB
Divide A by B
1
4
84
Decimal Adjust A
1
1
D4
DA A
LOGICAL
ANL A,Rn
AND register to A
1
1
58 to 5F
ANL A,dir
AND direct byte to A
2
1
55
ANL A,@Ri
AND indirect memory to A
1
1
56 to 57
ANL A,#data
AND immediate to A
2
1
54
ANL dir,A
AND A to direct byte
2
1
52
ANL dir,#data
AND immediate to direct byte
3
2
53
ORL A,Rn
OR register to A
1
1
48 to 4F
ORL A,dir
OR direct byte to A
2
1
45
ORL A,@Ri
OR indirect memory to A
1
1
46 to 47
ORL A,#data
OR immediate to A
2
1
44
ORL dir,A
OR A to direct byte
2
1
42
ORL dir,#data
OR immediate to direct byte
3
2
43
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Table 125: Instruction set summary …continued
Mnemonic
Description
Bytes
Cycles
Hex code
XRL A,Rn
Exclusive-OR register to A
1
1
68 to 6F
XRL A,dir
Exclusive-OR direct byte to A
2
1
65
XRL A, @Ri
Exclusive-OR indirect memory to A
1
1
66 to 67
XRL A,#data
Exclusive-OR immediate to A
2
1
64
XRL dir,A
Exclusive-OR A to direct byte
2
1
62
XRL dir,#data
Exclusive-OR immediate to direct byte
3
2
63
CLR A
Clear A
1
1
E4
CPL A
Complement A
1
1
F4
SWAP A
Swap Nibbles of A
1
1
C4
RL A
Rotate A left
1
1
23
RLC A
Rotate A left through carry
1
1
33
Rotate A right
RR A
1
1
03
RRC A
Rotate A right through carry
1
1
13
DATA TRANSFER
MOV A,Rn
Move register to A
1
1
E8 to EF
MOV A,dir
Move direct byte to A
2
1
E5
Move indirect memory to A
MOV A,@Ri
1
1
E6 to E7
MOV A,#data
Move immediate to A
2
1
74
MOV Rn,A
Move A to register
1
1
F8 to FF
MOV Rn,dir
Move direct byte to register
2
2
A8 to AF
MOV Rn,#data
Move immediate to register
2
1
78 to 7F
MOV dir,A
Move A to direct byte
2
1
F5
MOV dir,Rn
Move register to direct byte
2
2
88 to 8F
MOV dir,dir
Move direct byte to direct byte
3
2
85
MOV dir,@Ri
Move indirect memory to direct byte
2
2
86 to 87
MOV dir,#data
Move immediate to direct byte
3
2
75
MOV @Ri,A
Move A to indirect memory
1
1
F6 to F7
MOV @Ri,dir
Move direct byte to indirect memory
2
2
A6 to A7
MOV @Ri,#data
Move immediate to indirect memory
2
1
76 to 77
MOV DPTR,#data
Move immediate to data pointer
3
2
90
MOVC A,@A+DPTR
Move code byte relative DPTR to A
1
2
93
MOVC A,@A+PC
Move code byte relative PC to A
1
2
94
MOVX A,@Ri
Move external data(A8) to A
1
2
E2 to E3
MOVX A,@DPTR
Move external data(A16) to A
1
2
E0
MOVX @Ri,A
Move A to external data(A8)
1
2
F2 to F3
MOVX @DPTR,A
Move A to external data(A16)
1
2
F0
PUSH dir
Push direct byte onto stack
2
2
C0
POP dir
Pop direct byte from stack
2
2
D0
XCH A,Rn
Exchange A and register
1
1
C8 to CF
XCH A,dir
Exchange A and direct byte
2
1
C5
XCH A,@Ri
Exchange A and indirect memory
1
1
C6 to C7
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Table 125: Instruction set summary …continued
Mnemonic
Description
Bytes
Cycles
Hex code
XCHD A,@Ri
Exchange A and indirect memory nibble
1
1
D6 to D7
BOOLEAN
Mnemonic
Description
Bytes
Cycles
Hex code
CLR C
Clear carry
1
1
C3
CLR bit
Clear direct bit
2
1
C2
SETB C
Set carry
1
1
D3
SETB bit
Set direct bit
2
1
D2
CPL C
Complement carry
1
1
B3
CPL bit
Complement direct bit
2
1
B2
ANL C,bit
AND direct bit to carry
2
2
82
ANL C,/bit
AND direct bit inverse to carry
2
2
B0
ORL C,bit
OR direct bit to carry
2
2
72
ORL C,/bit
OR direct bit inverse to carry
2
2
A0
MOV C,bit
Move direct bit to carry
2
1
A2
Move carry to direct bit
2
2
92
MOV bit,C
BRANCHING
ACALL addr 11
Absolute jump to subroutine
2
2
116F1
LCALL addr 16
Long jump to subroutine
3
2
12
RET
Return from subroutine
1
2
22
RETI
Return from interrupt
1
2
32
AJMP addr 11
Absolute jump unconditional
2
2
016E1
LJMP addr 16
Long jump unconditional
3
2
02
SJMP rel
Short jump (relative address)
2
2
80
JC rel
Jump on carry = 1
2
2
40
JNC rel
Jump on carry = 0
2
2
50
JB bit,rel
Jump on direct bit = 1
3
2
20
JNB bit,rel
Jump on direct bit = 0
3
2
30
JBC bit,rel
Jump on direct bit = 1 and clear
3
2
10
JMP @A+DPTR
Jump indirect relative DPTR
1
2
73
JZ rel
Jump on accumulator = 0
2
2
60
JNZ rel
Jump on accumulator ≠ 0
2
2
70
CJNE A,dir,rel
Compare A, direct jne relative
3
2
B5
CJNE A,#d,rel
Compare A, immediate jne relative
3
2
B4
CJNE Rn,#d,rel
Compare register, immediate jne relative
3
2
B8 to BF
CJNE @Ri,#d,rel
Compare indirect, immediate jne relative
3
2
B6 to B7
DJNZ Rn,rel
Decrement register, jnz relative
2
2
D8 to DF
DJNZ dir,rel
Decrement direct byte, jnz relative
3
2
D5
1
1
00
MISCELLANEOUS
NOP
No operation
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21. 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
licence 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.
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.
22. Trademarks
Notice — All referenced brands, product names, service names and
trademarks are the property of their respective owners.
I2C-bus (logo) — is a trademark of Philips Semicondoctors.
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23. Contents
1
1.1
1.2
1.3
1.4
2
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.2.1
3.2.1.1
3.2.1.2
3.2.1.3
3.2.1.4
3.2.1.5
3.2.1.6
3.2.2
3.2.3
3.2.3.1
3.2.3.2
3.2.3.3
3.2.4
3.2.5
3.2.6
3.2.7
3.2.8
4
4.1
4.2
5
5.1
5.2
5.3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 5
Special function registers . . . . . . . . . . . . . . . . 10
Memory organization . . . . . . . . . . . . . . . . . . . 18
Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Enhanced CPU . . . . . . . . . . . . . . . . . . . . . . . . 19
Clock definitions . . . . . . . . . . . . . . . . . . . . . . . 19
Oscillator Clock (OSCCLK). . . . . . . . . . . . . . . 19
Low speed oscillator option . . . . . . . . . . . . . . 19
Medium speed oscillator option . . . . . . . . . . . 19
High speed oscillator option . . . . . . . . . . . . . . 19
Clock output . . . . . . . . . . . . . . . . . . . . . . . . . . 20
On-chip RC oscillator option . . . . . . . . . . . . . . 20
Watchdog oscillator option . . . . . . . . . . . . . . . 20
External clock input option . . . . . . . . . . . . . . . 21
Oscillator Clock (OSCCLK) wake-up delay. . . 22
CPU Clock (CCLK) modification: DIVM
register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Low power select . . . . . . . . . . . . . . . . . . . . . . 22
A/D converter . . . . . . . . . . . . . . . . . . . . . . . . . . 22
General description . . . . . . . . . . . . . . . . . . . . 22
A/D features . . . . . . . . . . . . . . . . . . . . . . . . . . 22
A/D operating modes . . . . . . . . . . . . . . . . . . . 23
Fixed channel, single conversion mode . . . . . 23
Fixed channel, continuous conversion mode . 24
Auto scan, single conversion mode . . . . . . . . 24
Auto scan, continuous conversion mode . . . . 24
Dual channel, continuous conversion mode . . 25
Single step mode . . . . . . . . . . . . . . . . . . . . . . 25
Conversion mode selection bits . . . . . . . . . . . 25
Conversion start modes . . . . . . . . . . . . . . . . . 26
Timer triggered start . . . . . . . . . . . . . . . . . . . . 26
Start immediately . . . . . . . . . . . . . . . . . . . . . . 26
Edge triggered . . . . . . . . . . . . . . . . . . . . . . . . 26
Stopping and restarting conversions . . . . . . . 26
Boundary limits interrupt. . . . . . . . . . . . . . . . . 26
Clock divider . . . . . . . . . . . . . . . . . . . . . . . . . . 27
I/O pins used with ADC functions . . . . . . . . . . 27
Power-down and Idle mode . . . . . . . . . . . . . . 27
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Interrupt priority structure . . . . . . . . . . . . . . . . 31
External Interrupt pin glitch suppression . . . . 31
I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Port configurations . . . . . . . . . . . . . . . . . . . . . 34
Quasi-bidirectional output configuration . . . . . 34
Open drain output configuration . . . . . . . . . . . 35
5.4
5.5
5.6
5.7
6
6.1
6.2
6.3
7
7.1
8
8.1
8.2
8.3
8.4
8.5
8.6
9
9.1
9.2
9.3
9.4
10
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
10.10
10.11
11
11.1
11.2
11.3
11.4
11.5
11.6
11.7
11.8
11.9
11.10
11.11
Input-only configuration . . . . . . . . . . . . . . . . .
Push-pull output configuration . . . . . . . . . . . .
Port 0 and Analog Comparator functions . . . .
Additional port features . . . . . . . . . . . . . . . . .
Power monitoring functions. . . . . . . . . . . . . .
Brownout detection . . . . . . . . . . . . . . . . . . . .
Power-on detection . . . . . . . . . . . . . . . . . . . .
Power reduction modes . . . . . . . . . . . . . . . . .
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset vector . . . . . . . . . . . . . . . . . . . . . . . . . .
Timers 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timer overflow toggle output . . . . . . . . . . . . .
Real-time clock system timer. . . . . . . . . . . . .
Real-time clock source. . . . . . . . . . . . . . . . . .
Changing RTCS1/RTCS0 . . . . . . . . . . . . . . .
Real-time clock interrupt/wake-up . . . . . . . . .
Reset sources affecting the Real-time clock .
Capture/Compare Unit (CCU). . . . . . . . . . . . .
CCU Clock (CCUCLK) . . . . . . . . . . . . . . . . . .
CCU Clock prescaling . . . . . . . . . . . . . . . . . .
Basic timer operation . . . . . . . . . . . . . . . . . . .
Output compare . . . . . . . . . . . . . . . . . . . . . . .
Input capture . . . . . . . . . . . . . . . . . . . . . . . . .
PWM operation . . . . . . . . . . . . . . . . . . . . . . .
Alternating output mode. . . . . . . . . . . . . . . . .
Synchronized PWM register update . . . . . . .
HALT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLL operation. . . . . . . . . . . . . . . . . . . . . . . . .
CCU interrupt structure . . . . . . . . . . . . . . . . .
UART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SFR space . . . . . . . . . . . . . . . . . . . . . . . . . . .
Baud Rate generator and selection . . . . . . . .
Updating the BRGR1 and BRGR0 SFRs. . . .
Framing error . . . . . . . . . . . . . . . . . . . . . . . . .
Break detect. . . . . . . . . . . . . . . . . . . . . . . . . .
More about UART Mode 0 . . . . . . . . . . . . . . .
More about UART Mode 1 . . . . . . . . . . . . . . .
36
36
37
37
38
38
40
40
43
45
45
46
47
47
47
47
49
50
51
51
51
51
53
54
54
54
56
58
59
60
61
61
61
62
65
65
65
66
66
66
66
67
67
68
69
70
continued >>
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11.12
11.13
11.14
11.15
11.16
11.17
11.18
11.19
11.20
12
12.1
12.2
12.3
12.4
12.5
12.6
12.6.1
12.6.2
12.6.3
12.6.4
13
13.1
13.2
13.3
13.4
13.5
13.6
13.7
14
14.1
14.2
14.3
14.4
14.5
14.6
15
16
16.1
16.2
16.3
16.4
16.5
16.6
17
More about UART Modes 2 and 3 . . . . . . . . . 71
Framing error and RI in Modes 2 and 3 with
SM2 = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Break detect . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Double buffering . . . . . . . . . . . . . . . . . . . . . . . 72
Double buffering in different modes . . . . . . . . 72
Transmit interrupts with double buffering enabled
(Modes 1, 2, and 3) . . . . . . . . . . . . . . . . . . . . 72
The 9th bit (bit 8) in double buffering (Modes 1, 2,
and 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Multiprocessor communications . . . . . . . . . . . 74
Automatic address recognition . . . . . . . . . . . . 75
I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
I2C data register . . . . . . . . . . . . . . . . . . . . . . . 77
I2C slave address register . . . . . . . . . . . . . . . 77
2
I C control register . . . . . . . . . . . . . . . . . . . . . 78
I2C Status register . . . . . . . . . . . . . . . . . . . . . 79
I2C SCL duty cycle registers I2SCLH and
I2SCLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
I2C operation modes. . . . . . . . . . . . . . . . . . . . 80
Master Transmitter mode . . . . . . . . . . . . . . . . 80
Master Receiver mode . . . . . . . . . . . . . . . . . . 81
Slave Receiver mode . . . . . . . . . . . . . . . . . . . 82
Slave Transmitter mode . . . . . . . . . . . . . . . . . 83
Serial Peripheral Interface (SPI) . . . . . . . . . . . 90
Configuring the SPI . . . . . . . . . . . . . . . . . . . . 94
Additional considerations for a slave . . . . . . . 95
Additional considerations for a master . . . . . . 95
Mode change on SS . . . . . . . . . . . . . . . . . . . . 95
Write collision . . . . . . . . . . . . . . . . . . . . . . . . . 96
Data mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
SPI clock prescaler select. . . . . . . . . . . . . . . 100
Analog comparators . . . . . . . . . . . . . . . . . . . 100
Comparator configuration . . . . . . . . . . . . . . . 100
Internal reference voltage . . . . . . . . . . . . . . . 102
Comparator input pins . . . . . . . . . . . . . . . . . 102
Comparator interrupt . . . . . . . . . . . . . . . . . . 102
Comparators and power reduction modes . . 102
Comparators configuration example . . . . . . . 103
Keypad interrupt (KBI). . . . . . . . . . . . . . . . . . 104
Watchdog timer (WDT) . . . . . . . . . . . . . . . . . 105
Watchdog function . . . . . . . . . . . . . . . . . . . . 105
Feed sequence . . . . . . . . . . . . . . . . . . . . . . . 106
Watchdog clock source . . . . . . . . . . . . . . . . 109
Watchdog Timer in Timer mode . . . . . . . . . . 110
Power-down operation . . . . . . . . . . . . . . . . . 111
Periodic wake-up from power-down without an
external oscillator . . . . . . . . . . . . . . . . . . . . . 111
Additional features . . . . . . . . . . . . . . . . . . . . 111
17.1
17.2
18
18.1
18.2
18.3
18.4
18.5
18.6
18.7
19
19.1
19.2
19.3
19.4
19.5
19.6
19.7
19.8
19.9
19.10
19.11
19.12
19.13
19.14
19.15
19.16
19.17
19.18
19.19
19.20
20
21
22
Software reset . . . . . . . . . . . . . . . . . . . . . . . 112
Dual Data Pointers . . . . . . . . . . . . . . . . . . . . 112
Data EEPROM . . . . . . . . . . . . . . . . . . . . . . . . 112
Data EEPROM read. . . . . . . . . . . . . . . . . . . 113
Data EEPROM write . . . . . . . . . . . . . . . . . . 114
Hardware reset . . . . . . . . . . . . . . . . . . . . . . 114
Multiple writes to the DEEDAT register . . . . 114
Sequences of writes to DEECON and DEEDAT
registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Data EEPROM Row Fill . . . . . . . . . . . . . . . . 114
Data EEPROM Block Fill . . . . . . . . . . . . . . . 115
Flash memory . . . . . . . . . . . . . . . . . . . . . . . . 115
General description . . . . . . . . . . . . . . . . . . . 115
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Flash programming and erase . . . . . . . . . . . 116
Using Flash as data storage: IAP-Lite . . . . . 116
In-circuit programming (ICP) . . . . . . . . . . . . 120
ISP and IAP capabilities of the P89LPC938 120
Boot ROM . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Power on reset code execution . . . . . . . . . . 120
Hardware activation of Boot Loader. . . . . . . 121
In-system programming (ISP) . . . . . . . . . . . 121
Using the In-system programming (ISP) . . . 122
In-application programming (IAP) . . . . . . . . 125
IAP authorization key . . . . . . . . . . . . . . . . . . 126
Flash write enable . . . . . . . . . . . . . . . . . . . . 126
Configuration byte protection . . . . . . . . . . . . 126
IAP error status . . . . . . . . . . . . . . . . . . . . . . 127
User configuration bytes . . . . . . . . . . . . . . . 130
User security bytes . . . . . . . . . . . . . . . . . . . 131
Boot Vector register . . . . . . . . . . . . . . . . . . . 132
Boot status register . . . . . . . . . . . . . . . . . . . 132
Instruction set . . . . . . . . . . . . . . . . . . . . . . . . 134
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . 137
© Koninklijke Philips Electronics N.V. 2005
All rights are reserved. Reproduction in whole or in part is prohibited without the prior
written consent of the copyright owner. The information presented in this document does
not form part of any quotation or contract, is believed to be accurate and reliable and may
be changed without notice. No liability will be accepted by the publisher for any
consequence of its use. Publication thereof does not convey nor imply any license under
patent- or other industrial or intellectual property rights.
Date of release: 7 June 2005
Published in the Netherlands