ATMEL AT89C55WD-33JC 8-bit microcontroller with 20k bytes flash Datasheet

Features
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Compatible with MCS®-51 Products
20K Bytes of Reprogrammable Flash Memory
Endurance: 1000 Write/Erase Cycles
4V to 5.5V Operating Range
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Programmable Serial Channel
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down Mode
Hardware Watchdog Timer
Dual Data Pointer
Power-off Flag
8-bit
Microcontroller
with 20K Bytes
Flash
Description
The AT89C55WD is a low-power, high-performance CMOS 8-bit microcontroller with
20K bytes of Flash programmable read only memory and 256 bytes of RAM. The
device is manufactured using Atmel’s high-density nonvolatile memory technology and
is compatible with the industry standard 80C51 and 80C52 instruction set and pinout.
The on-chip Flash allows the program memory to be user programmed by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash
on a monolithic chip, the Atmel AT89C55WD is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control
applications.
AT89C55WD
The AT89C55WD provides the following standard features: 20K bytes of Flash, 256
bytes of RAM, 32 I/O lines, three 16-bit timer/counters, a six-vector, two-level interrupt
architecture, a full-duplex serial port, on-chip oscillator, and clock circuitry. In addition,
the AT89C55WD is designed with static logic for operation down to zero frequency
and supports two software selectable power saving modes. The Idle Mode stops the
CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the
oscillator, disabling all other chip functions until the next external interrupt or hardware
reset.
Rev. 1921B–MICRO–09/02
1
Pin Configurations
44
43
42
41
40
39
38
37
36
35
34
P1.4
P1.3
P1.2
P1.1 (T2 EX)
P1.0 (T2)
NC
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
TQFP
33
32
31
30
29
28
27
26
25
24
23
1
2
3
4
5
6
7
8
9
10
11
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
NC
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
GND
(A8) P2.0
(A9) P2.1
(A10) P2.2
(A11) P2.3
(A12) P2.4
12
13
14
15
16
17
18
19
20
21
22
P1.5
P1.6
P1.7
RST
(RXD) P3.0
NC
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
PDIP
(T2) P1.0
(T2EX) P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
(RXD) P3.0
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
P2.4 (A12)
P2.3 (A11)
P2.2 (A10)
P2.1 (A9)
P2.0 (A8)
39
38
37
36
35
34
33
32
31
30
29
18
19
20
21
22
23
24
25
26
27
28
7
8
9
10
11
12
13
14
15
16
17
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
NC
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
NC
(A8) P2.0
(A9) P2.1
(A10) P2.2
(A11) P2.3
(A12) P2.4
P1.5
P1.6
P1.7
RST
(RXD) P3.0
NC
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
6
5
4
3
2
1
44
43
42
41
40
P1.4
P1.3
P1.2
P1.1 (T2 EX)
P1.0 (T2)
NC
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
PLCC
2
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Block Diagram
P0.0 - P0.7
P2.0 - P2.7
PORT 0 DRIVERS
PORT 2 DRIVERS
VCC
GND
RAM ADDR.
REGISTER
B
REGISTER
PORT 0
LATCH
RAM
QUICK
FLASH
PORT 2
LATCH
STACK
POINTER
ACC
BUFFER
TMP1
TMP2
PROGRAM
ADDRESS
REGISTER
PC
INCREMENTER
ALU
INTERRUPT, SERIAL PORT,
AND TIMER BLOCKS
PROGRAM
COUNTER
PSW
PSEN
ALE/PROG
EA / VPP
TIMING
AND
CONTROL
DUAL
DPTR
INSTRUCTION
REGISTER
RST
WATCH
DOG
PORT 1
LATCH
PORT 3
LATCH
PORT 1 DRIVERS
PORT 3 DRIVERS
OSC
P1.0 - P1.7
P3.0 - P3.7
3
1921B–MICRO–09/02
Pin Description
VCC
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight
TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance
inputs.
Port 0 can also be configured to be the multiplexed low-order address/data bus during
accesses to external program and data memory. In this mode, P0 has internal pull-ups.
Port 0 also receives the code bytes during Flash programming and outputs the code bytes
during program verification. External pull-ups are required during program verification.
Port 1
Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers can
sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being
pulled low will source current (IIL) because of the internal pull-ups.
In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input
(P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table.
Port 1 also receives the low-order address bytes during Flash programming and verification.
Port 2
Port Pin
Alternate Functions
P1.0
T2 (external count input to Timer/Counter 2), clock-out
P1.1
T2EX (Timer/Counter 2 capture/reload trigger and direction control)
Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can
sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being
pulled low will source current (IIL) because of the internal pull-ups.
Port 2 emits the high-order address byte during fetches from external program memory and
during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this
application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external
data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.
Port 3
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can
sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being
pulled low will source current (IIL) because of the pull-ups.
Port 3 receives some control signals for Flash programming and verification.
Port 3 also serves the functions of various special features of the AT89C55WD, as shown in
the following table.
4
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Port Pin
Alternate Functions
P3.0
RXD (serial input port)
P3.1
TXD (serial output port)
P3.2
INT0 (external interrupt 0)
P3.3
INT1 (external interrupt 1)
P3.4
T0 (timer 0 external input)
P3.5
T1 (timer 1 external input)
P3.6
WR (external data memory write strobe)
P3.7
RD (external data memory read strobe)
RST
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the
device. This pin drives High for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state
of bit DISRTO, the RESET HIGH out feature is enabled.
ALE/PROG
Address Latch Enable is an output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse input (PROG) during Flash
programming.
In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may
be used for external timing or clocking purposes. Note, however, that one ALE pulse is
skipped during each access to external data memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set,
ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled
high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution
mode.
PSEN
Program Store Enable is the read strobe to external program memory.
When the AT89C55WD is executing code from external program memory, PSEN is activated
twice each machine cycle, except that two PSEN activations are skipped during each access
to external data memory.
EA/VPP
External Access Enable. EA must be strapped to GND in order to enable the device to fetch
code from external program memory locations starting at 0000H up to FFFFH. Note, however,
that if lock bit 1 is programmed, EA will be internally latched on reset.
EA should be strapped to VCC for internal program executions.
This pin also receives the 12V programming enable voltage (VPP) during Flash programming.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
5
1921B–MICRO–09/02
Table 1. AT89C55WD SFR Map and Reset Values
0F8H
0F0H
0FFH
B
00000000
0F7H
0E8H
0E0H
0EFH
ACC
00000000
0E7H
0D8H
0DFH
0D0H
PSW
00000000
0C8H
T2CON
00000000
0D7H
T2MOD
XXXXXX00
RCAP2L
00000000
RCAP2H
00000000
TL2
00000000
TH2
00000000
0CFH
0C0H
0C7H
0B8H
IP
XX000000
0BFH
0B0H
P3
11111111
0B7H
0A8H
IE
0X000000
0AFH
0A0H
P2
11111111
98H
SCON
00000000
90H
P1
11111111
88H
TCON
00000000
TMOD
00000000
TL0
00000000
TL1
00000000
TH0
00000000
TH1
00000000
80H
P0
11111111
SP
00000111
DP0L
00000000
DP0H
00000000
DP1L
00000000
DP1H
00000000
Special
Function
Registers
AUXR1
XXXXXXX0
WDTRST
XXXXXXXX
0A7H
SBUF
XXXXXXXX
9FH
97H
AUXR
XXX00XX0
8FH
PCON
0XXX0000
87H
A map of the on-chip memory area called the Special Function Register (SFR) space is shown
in Table 1.
Note that not all of the addresses are occupied, and unoccupied addresses may not be implemented on the chip. Read accesses to these addresses will in general return random data,
and write accesses will have an indeterminate effect.
User software should not write 1s to these unlisted locations, since they may be used in future
products to invoke new features. In that case, the reset or inactive values of the new bits will
always be 0.
Timer 2 Registers: Control and status bits are contained in registers T2CON (shown in Table
2) and T2MOD (shown in Table 2) for Timer 2. The register pair (RCAP2H, RCAP2L) are the
Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode.
6
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Interrupt Registers: The individual interrupt enable bits are in the IE register. Two priorities
can be set for each of the six interrupt sources in the IP register.
Table 2. T2CON—Timer/Counter 2 Control Register
T2CON Address = 0C8H
Reset Value = 0000 0000B
Bit Addressable
Bit
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
7
6
5
4
3
2
1
0
Table 3. AUXR: Auxiliary Register
AUXR
Address = 8EH
Reset Value = XXX00XX0B
Not Bit Addressable
Bit
–
–
–
WDIDLE
DISRTO
–
–
DISALE
7
6
5
4
3
2
1
0
–
Reserved for future expansion
DISALE
Disable/Enable ALE
DISRTO
WDIDLE
DISALE
Operating Mode
0
ALE is emitted at a constant rate of 1/6 the oscillator frequency
1
ALE is active only during a MOVX or MOVC instruction
Disable/Enable Reset out
DISRTO
Operating Mode
0
Reset pin is driven High after WDT times out
1
Reset pin is input only
Disable/Enable WDT in IDLE mode
WDIDLE
Operating Mode
0
WDT continues to count in IDLE mode
1
WDT halts counting in IDLE mode
Dual Data Pointer Registers: To facilitate accessing both internal and external data memory,
two banks of 16-bit Data Pointer Registers are provided: DP0 at SFR address locations 82H83H and DP1 at 84H-85H. Bit DPS = 0 in SFR AUXR1 selects DP0 and DPS = 1 selects DP1.
The user should always initialize the DPS bit to the appropriate value before accessing the
respective Data Pointer Register.
Power Off Flag: The Power Off Flag (POF) is located at bit 4 (PCON.4) in the PCON SFR.
POF is set to “1” during power up. It can be set and rest under software control and is not
affected by reset.
7
1921B–MICRO–09/02
Table 4. AUXR1: Auxiliary Register 1
AUXR1
Address = A2H
Reset Value = XXXXXXX0B
Not Bit Addressable
Bit
–
–
–
–
–
–
–
DPS
7
6
5
4
3
2
1
0
–
Reserved for future expansion
DPS
Data Pointer Register Select
DPS
8
0
Selects DPTR Registers DP0L, DP0H
1
Selects DPTR Registers DP1L, DP1H
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Memory
Organization
MCS-51 devices have a separate address space for Program and Data Memory. Up to
64 Kbytes each of external Program and Data Memory can be addressed.
Program Memory
If the EA pin is connected to GND, all program fetches are directed to external memory.
On the AT89C55WD, if EA is connected to VCC, program fetches to addresses 0000H through
4FFFH are directed to internal memory and fetches to addresses 5000H through FFFFH are
to external memory.
Data Memory
The AT89C55WD implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. That means the upper 128 bytes have
the same addresses as the SFR space but are physically separate from SFR space.
When an instruction accesses an internal location above address 7FH, the address mode
used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the
SFR space. Instructions that use direct addressing access SFR space.
For example, the following direct addressing instruction accesses the SFR at location 0A0H
(which is P2).
MOV 0A0H, #data
Instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the
following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at
address 0A0H, rather than P2 (whose address is 0A0H).
MOV @R0, #data
Note that stack operations are examples of indirect addressing, so the upper 128 bytes of data
RAM are available as stack space.
9
1921B–MICRO–09/02
Hardware
Watchdog
Timer
(One-time
Enabled with
Reset-out)
The WDT is intended as a recovery method in situations where the CPU may be subjected to
software upsets. The WDT consists of a 13-bit counter and the WatchDog Timer Reset
(WDTRST) SFR. The WDT is defaulted to disable from exiting reset. To enable the WDT, a
user must write 01EH and 0E1H in sequence to the WDTRST register (SFR location 0A6H).
When the WDT is enabled, it will increment every machine cycle while the oscillator is running.
The WDT time-out period is dependent on the external clock frequency. There is no way to
disable the WDT except through reset (either hardware reset or WDT overflow reset). When
WDT overflows, it will drive an output RESET HIGH pulse at the RST pin.
Using the WDT
To enable the WDT, a user must write 01EH and 0E1H in sequence to the WDTRST register
(SFR location 0A6H). When the WDT is enabled, the user needs to service it by writing 01EH
and 0E1H to WDTRST to avoid a WDT overflow. The 13-bit counter overflows when it reaches
8191 (1FFFH), and this will reset the device. When the WDT is enabled, it will increment every
machine cycle while the oscillator is running. This means the user must reset the WDT at least
every 8191 machine cycles. To reset the WDT the user must write 01EH and 0E1H to
WDTRST. WDTRST is a write-only register. The WDT counter cannot be read or written.
When WDT overflows, it will generate an output RESET pulse at the RST pin. The RESET
pulse duration is 98xTOSC, where TOSC=1/FOSC. To make the best use of the WDT, it
should be serviced in those sections of code that will periodically be executed within the time
required to prevent a WDT reset.
WDT During
Power-down
and Idle
In Power-down mode the oscillator stops, which means the WDT also stops. While in Powerdown mode, the user does not need to service the WDT. There are two methods of exiting
Power-down mode: by a hardware reset or via a level-activated external interrupt which is
enabled prior to entering Power-down mode. When Power-down is exited with hardware reset,
servicing the WDT should occur as it normally does whenever the AT89C55WD is reset. Exiting Power-down with an interrupt is significantly different. The interrupt is held low long
enough for the oscillator to stabilize. When the interrupt is brought high, the interrupt is serviced. To prevent the WDT from resetting the device while the interrupt pin is held low, the
WDT is not started until the interrupt is pulled high. It is suggested that the WDT be reset during the interrupt service for the interrupt used to exit Power-down.
To ensure that the WDT does not overflow within a few states of exiting Power-down, it is best
to reset the WDT just before entering Power-down.
Before going into the IDLE mode, the WDIDLE bit in SFR AUXR is used to determine whether
the WDT continues to count if enabled. The WDT keeps counting during IDLE (WDIDLE bit =
0) as the default state. To prevent the WDT from resetting the AT89C55WD while in IDLE
mode, the user should always set up a timer that will periodically exit IDLE, service the WDT,
and reenter IDLE mode.
With WDIDLE bit enabled, the WDT will stop to count in IDLE mode and resumes the count
upon exit from IDLE.
UART
10
The UART in the AT89C55WD operates the same way as the UART in the AT89C51 and
AT89C52. For further information, see the December 1997 Microcontroller Data Book, page 248, section titled, “Serial Interface”.
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Timer 0 and 1
Timer 0 and Timer 1 in the AT89C55WD operate the same way as Timer 0 and Timer 1 in the
AT89C51 and AT89C52.
Timer 2
Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter. The
type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 2). Timer 2 has
three operating modes: capture, auto-reload (up or down counting), and baud rate generator.
The modes are selected by bits in T2CON, as shown in Table 2.
Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is
incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods, the
count rate is 1/12 of the oscillator frequency.
Table 5. Timer 2 Operating Modes
RCLK +TCLK
CP/RL2
TR2
MODE
0
0
1
16-bit Auto-Reload
0
1
1
16-bit Capture
1
X
1
Baud Rate Generator
X
X
0
(Off)
In the Counter function, the register is incremented in response to a 1-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled during S5P2 of
every machine cycle. When the samples show a high in one cycle and a low in the next cycle,
the count is incremented. The new count value appears in the register during S3P1 of the
cycle following the one in which the transition was detected. Since two machine cycles (24
oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24
of the oscillator frequency. To ensure that a given level is sampled at least once before it
changes, the level should be held for at least one full machine cycle.
Capture Mode
In the capture mode, two options are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2
is a 16-bit timer or counter which upon overflow sets bit TF2 in T2CON. This bit can then be
used to generate an interrupt. If EXEN2 = 1, Timer 2 performs the same operation, but a 1-to0 transition at external input T2EX also causes the current value in TH2 and TL2 to be captured into RCAP2H and RCAP2L, respectively. In addition, the transition at T2EX causes bit
EXF2 in T2CON to be set. The EXF2 bit, like TF2, can generate an interrupt. The capture
mode is illustrated in Figure 5.
Auto-reload (Up or
Down Counter)
Timer 2 can be programmed to count up or down when configured in its 16-bit auto-reload
mode. This feature is invoked by the DCEN (Down Counter Enable) bit located in the SFR
T2MOD (see Table 6). Upon reset, the DCEN bit is set to 0 so that timer 2 will default to count
up. When DCEN is set, Timer 2 can count up or down, depending on the value of the T2EX
pin.
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1921B–MICRO–09/02
Figure 5. Timer in Capture Mode
÷12
OSC
C/T2 = 0
TH2
TL2
OVERFLOW
CONTROL
C/T2 = 1
TF2
TR2
CAPTURE
T2 PIN
RCAP2H RCAP2L
TRANSITION
DETECTOR
TIMER 2
INTERRUPT
T2EX PIN
EXF2
CONTROL
EXEN2
Figure 6 shows Timer 2 automatically counting up when DCEN=0. In this mode, two options
are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to 0FFFFH and then
sets the TF2 bit upon overflow. The overflow also causes the timer registers to be reloaded
with the 16-bit value in RCAP2H and RCAP2L. The values in Timer in Capture ModeRCAP2H
and RCAP2L are preset by software. If EXEN2 = 1, a 16-bit reload can be triggered either by
an overflow or by a 1-to-0 transition at external input T2EX. This transition also sets the EXF2
bit. Both the TF2 and EXF2 bits can generate an interrupt if enabled.
Setting the DCEN bit enables Timer 2 to count up or down, as shown in Figure 6. In this mode,
the T2EX pin controls the direction of the count. A logic 1 at T2EX makes Timer 2 count up.
The timer will overflow at 0FFFFH and set the TF2 bit. This overflow also causes the 16-bit
value in RCAP2H and RCAP2L to be reloaded into the timer registers, TH2 and TL2,
respectively.
A logic 0 at T2EX makes Timer 2 count down. The timer underflows when TH2 and TL2 equal
the values stored in RCAP2H and RCAP2L. The underflow sets the TF2 bit and causes
0FFFFH to be reloaded into the timer registers.
The EXF2 bit toggles whenever Timer 2 overflows or underflows and can be used as a 17th bit
of resolution. In this operating mode, EXF2 does not flag an interrupt.
12
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Figure 6. Timer 2 Auto Reload Mode (DCEN = 0)
÷12
OSC
C/T2 = 0
TH2
TL2
OVERFLOW
CONTR OL
TR2
C/T2 = 1
RELO AD
T2 PIN
RCAP2H
TIMER 2
INTERRUPT
RCAP2L
TF2
TRANSITION
DETECTOR
EXF2
T2EX PIN
CONTROL
EXEN2
Table 6. T2MOD – Timer 2 Mode Control Register
T2MOD Address = 0C9H
Reset Value = XXXX XX00B
Not Bit Addressable
Bit
–
–
–
–
–
–
T2OE
DCEN
7
6
5
4
3
2
1
0
Symbol
Function
–
Not implemented, reserved for future
T2OE
Timer 2 Output Enable bit
DCEN
When set, this bit allows Timer 2 to be configured as an up/down counter
13
1921B–MICRO–09/02
Figure 7. Timer 2 Auto Reload Mode (DCEN = 1)
TOGGLE
(DOWN COUNTING RELOAD VALUE)
0FFH
0FFH
÷ 12
OSC
EXF2
OVERFLOW
C/T2 = 0
TH2
TL2
TF2
CONTROL
TR2
TIMER 2
INTERRUPT
C/T2 = 1
T2 PIN
RCAP2H RCAP2L
COUNT
DIRECTION
1=UP
0=DO
(UP COUNTING RELOAD VALUE)
T2EX PIN
Figure 8. Timer 2 in Baud Rate Generator Mode
TIMER 1 OVERFLOW
÷2
"0"
"1"
NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12
SMOD1
OSC
÷2
C/T2 = 0
"1"
TH2
"0"
TL2
RCLK
CONTROL
TR2
÷ 16
Rx
CLOCK
C/T2 = 1
"1"
"0"
T2 PIN
TCLK
RCAP2H RCAP2L
TRANSITION
DETECTOR
÷ 16
T2EX PIN
EXF2
Tx
CLOCK
TIMER 2
INTERRUPT
CONTROL
EXEN2
14
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Baud Rate
Generator
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON (Table
2). Note that the baud rates for transmit and receive can be different if Timer 2 is used for the
receiver or transmitter and Timer 1 is used for the other function. Setting RCLK and/or TCLK
puts Timer 2 into its baud rate generator mode, as shown in Figure 8.
The baud rate generator mode is similar to the auto-reload mode, in that a rollover in TH2
causes the Timer 2 registers to be reloaded with the 16-bit value in registers RCAP2H and
RCAP2L, which are preset by software.
The baud rates in Modes 1 and 3 are determined by Timer 2’s overflow rate according to the
following equation.
Timer 2 Overflow Rate
Modes 1 and 3 Baud Rates = -----------------------------------------------------------16
The Timer can be configured for either timer or counter operation. In most applications, it is
configured for timer operation (CP/T2 = 0). The timer operation is different for Timer 2 when it
is used as a baud rate generator. Normally, as a timer, it increments every machine cycle (at
1/12 the oscillator frequency). As a baud rate generator, however, it increments every state
time (at 1/2 the oscillator frequency). The baud rate formula is given below.
Modes 1 and 3
Oscillator Frequency
--------------------------------------- = -------------------------------------------------------------------------------------Baud Rate
32 x [65536-RCAP2H,RCAP2L)]
where (RCAP2H, RCAP2L) is the content of RCAP2H and RCAP2L taken as a 16-bit
unsigned integer.
Timer 2 as a baud rate generator is shown in Figure 8. This figure is valid only if RCLK or
TCLK = 1 in T2CON. Note that a rollover in TH2 does not set TF2 and will not generate an
interrupt. Note too, that if EXEN2 is set, a 1-to-0 transition in T2EX will set EXF2 but will not
cause a reload from (RCAP2H, RCAP2L) to (TH2, TL2). Thus when Timer 2 is in use as a
baud rate generator, T2EX can be used as an extra external interrupt.
Note that when Timer 2 is running (TR2 = 1) as a timer in the baud rate generator mode, TH2
or TL2 should not be read from or written to. Under these conditions, the Timer is incremented
every state time, and the results of a read or write may not be accurate. The RCAP2 registers
may be read but should not be written to, because a write might overlap a reload and cause
write and/or reload errors. The timer should be turned off (clear TR2) before accessing the
Timer 2 or RCAP2 registers.
15
1921B–MICRO–09/02
Figure 9. Timer 2 in Clock-Out Mode
TL2
(8-BITS)
2
OSC
TH2
(8-BITS)
TR2
RCAP2L RCAP2H
C/T2 BIT
P1.0
(T2)
2
T2OE (T2MOD.1)
TRANSITION
DETECTOR
P1.1
(T2EX)
EXF2
TIMER 2
INTERRUPT
EXEN2
16
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Programmable
Clock Out
A 50% duty cycle clock can be programmed to come out on P1.0, as shown in Figure 9. This
pin, besides being a regular I/O pin, has two alternate functions. It can be programmed to input
the external clock for Timer/Counter 2 or to output a 50% duty cycle clock ranging from 61 Hz
to 4 MHz for a 16 MHz operating frequency.
To configure the Timer/Counter 2 as a clock generator, bit C/T2 (T2CON.1) must be cleared
and bit T2OE (T2MOD.1) must be set. Bit TR2 (T2CON.2) starts and stops the timer.
The clock-out frequency depends on the oscillator frequency and the reload value of Timer 2
capture registers (RCAP2H, RCAP2L), as shown in the following equation.
Oscillator Frequency
Clock-Out Frequency = ------------------------------------------------------------------------------------4 x [65536-(RCAP2H,RCAP2L)]
In the clock-out mode, Timer 2 roll-overs will not generate an interrupt. This behavior is similar
to when Timer 2 is used as a baud-rate generator. It is possible to use Timer 2 as a baud-rate
generator and a clock generator simultaneously. Note, however, that the baud-rate and clockout frequencies cannot be determined independently from one another since they both use
RCAP2H and RCAP2L.
Interrupts
The AT89C55WD has a total of six interrupt vectors: two external interrupts (INT0 and INT1),
three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are all
shown in Figure 10.
Each of these interrupt sources can be individually enabled or disabled by setting or clearing a
bit in Special Function Register IE. IE also contains a global disable bit, EA, which disables all
interrupts at once.
Note that Table 5 shows that bit position IE.6 is unimplemented. User software should not
write a ‘1’ to this bit position, since it may be used in future AT89 products.
Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the
service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and that bit will have to be cleared in software.
The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers
overflow. The values are then polled by the circuitry in the next cycle. However, the Timer 2
flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.
17
1921B–MICRO–09/02
Table 7. Interrupt Enable (IE) Register
(MSB)
EA
(LSB)
–
ET2
ES
ET1
EX1
ET0
EX0
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
Symbol
Position
Function
EA
IE.7
Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA
= 1, each interrupt source is individually enabled or disabled by
setting or clearing its enable bit.
–
IE.6
Reserved.
ET2
IE.5
Timer 2 interrupt enable bit.
ES
IE.4
Serial Port interrupt enable bit.
ET1
IE.3
Timer 1 interrupt enable bit.
EX1
IE.2
External interrupt 1 enable bit.
ET0
IE.1
Timer 0 interrupt enable bit.
EX0
IE.0
External interrupt 0 enable bit.
User software should never write 1s to reserved bits, because they may be used in future AT89
products.
Figure 10. Interrupt Sources
0
IE0
INT0
1
TF0
0
INT1
IE1
1
TF1
TI
RI
TF2
EXF2
18
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Oscillator
Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that can be
configured for use as an on-chip oscillator, as shown in Figure 11. Either a quartz crystal or
ceramic resonator may be used. To drive the device from an external clock source, XTAL2
should be left unconnected while XTAL1 is driven, as shown in Figure 12. There are no
requirements on the duty cycle of the external clock signal, since the input to the internal
clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high
and low time specifications must be observed.
Idle Mode
In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active. The
mode is invoked by software. The content of the on-chip RAM and all the special functions
registers remain unchanged during this mode. The idle mode can be terminated by any
enabled interrupt or by a hardware reset.
Note that when idle mode is terminated by a hardware reset, the device normally resumes program execution from where it left off, up to two machine cycles before the internal reset
algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but
access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a
port pin when idle mode is terminated by a reset, the instruction following the one that invokes
idle mode should not write to a port pin or to external memory.
Power-down
Mode
In the Power-down mode, the oscillator is stopped, and the instruction that invokes Powerdown is the last instruction executed. The on-chip RAM and Special Function Registers retain
their values until the Power-down mode is terminated. Exit from Power-down can be initiated
either by a hardware reset or by an enabled external interrupt. Reset redefines the SFRs but
does not change the on-chip RAM. The reset should not be activated before VCC is restored to
its normal operating level and must be held active long enough to allow the oscillator to restart
and stabilize.
Figure 11. Oscillator Connections
C2
XTAL2
C1
XTAL1
GND
Note:
C1, C2 = 30 pF ± 10 pF for Crystals
= 40 pF ± 10 pF for Ceramic Resonators
19
1921B–MICRO–09/02
Figure 12. External Clock Drive Configuration
NC
XTAL2
EXTERNAL
OSCILLATOR
SIGNAL
XTAL1
GND
Table 8. Status of External Pins During Idle and Power-down Modes
Mode
Program Memory
ALE
PSEN
PORT0
PORT1
PORT2
PORT3
Idle
Internal
1
1
Data
Data
Data
Data
Idle
External
1
1
Float
Data
Address
Data
Power-down
Internal
0
0
Data
Data
Data
Data
Power-down
External
0
0
Float
Data
Data
Data
20
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Program
Memory Lock
Bits
The AT89C55WD has three lock bits that can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the following table.
Table 9. Lock Bit Protection Modes
Program Lock Bits
1
LB1
LB2
LB3
Protection Type
U
U
U
No program lock features.
2
P
U
U
MOVC instructions executed from external program memory are
disabled from fetching code bytes from internal memory, EA is
sampled and latched on reset, and further programming of the Flash
memory is disabled.
3
P
P
U
Same as mode 2, but verify is also disabled.
4
P
P
P
Same as mode 3, but external execution is also disabled.
When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during
reset. If the device is powered up without a reset, the latch initializes to a random value and
holds that value until reset is activated. The latched value of EA must agree with the current
logic level at that pin in order for the device to function properly.
Programming
the Flash
The AT89C55WD is shipped with the on-chip Flash memory array ready to be programmed.
The programming interface needs a high-voltage (12-volt) program enable signal and is compatible with conventional third-party Flash or EPROM programmers.
The AT89C55WD code memory array is programmed byte-by-byte.
Programming Algorithm: Before programming the AT89C55WD, the address, data, and
control signals should be set up according to the Flash programming mode table and Figures
13 and 14. To program the AT89C55WD, take the following steps:
1. Input the desired memory location on the address lines.
2. Input the appropriate data byte on the data lines.
3. Activate the correct combination of control signals.
4. Raise EA/VPP to 12V.
5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The bytewrite cycle is self-timed and typically takes no more than 50 µs. Repeat steps 1
through 5, changing the address and data for the entire array or until the end of the
object file is reached.
Chip Erase Sequence: Before the AT89C55WD can be reprogrammed, a Chip Erase operation needs to be performed. To erase the contents of the AT89C55WD, follow this sequence:
1. Raise VCC to 6.5V.
2. Pulse ALE/PROG once (duration of 200 - 500 ns).
3. Wait for 150 ms.
4. Power VCC down and up to 6.5V.
5. Pulse ALE/PROG once (duration of 200 - 500 ns).
6. Wait for 150 ms.
7. Power VCC down and up to 6.5V.
Data Polling: The AT89C55WD features Data Polling to indicate the end of a write cycle. During a write cycle, an attempted read of the last byte written will result in the complement of the
written data on P0.7. Once the write cycle has been completed, true data is valid on all out21
1921B–MICRO–09/02
puts, and the next cycle may begin. Data Polling may begin any time after a write cycle has
been initiated.
Ready/Busy: The progress of byte programming can also be monitored by the RDY/BSY output signal. P3.0 is pulled low after ALE goes high during programming to indicate BUSY. P3.0
is pulled high again when programming is done to indicate READY.
Program Verify: If lock bits LB1 and LB2 have not been programmed, the programmed code
data can be read back via the address and data lines for verification. The status of the individual lock bits can be directly verified by reading them back.
Reading the Signature Bytes: The signature bytes are read by the same procedure as a normal verification of locations 000H, 100H, and 200H, except that P3.6 and P3.7 must be pulled
to a logic low. The values returned are as follows:
(000H) = 1EH indicates manufactured by Atmel
(100H) = 55H
(200H) = 06H indicates 89C55WD
22
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Programming
Interface
Every code byte in the Flash array can be programmed by using the appropriate combination
of control signals. The write operation cycle is self-timed and once initiated, will automatically
time itself to completion.
Most worldwide major programming vendors offer support for the Atmel microcontroller series.
Please contact your local programming vendor for the appropriate software revision.
Table 10. Flash Programming Modes
Mode
VCC
RST
PSEN
ALE/
PROG
P3.4
P2.5-0
P1.7-0
EA/
VPP
P2.6
P2.7
P3.3
P3.6
P3.7
P0.7-0
Data
12V
L
H
H
H
H
DIN
A14
A13-8
A7-0
H/12V
L
L
L
H
H
DOUT
A14
A13-8
A7-0
12V
H
H
H
H
H
X
X
X
X
12V
H
H
H
L
L
X
X
X
X
12V
H
L
H
H
L
X
X
X
X
H
H
H
L
H
L
P0.2,
P0.3,
P0.4
X
X
X
12V
H
L
H
L
L
X
X
X
X
Address
(1)
Write Code Data
5V
H
L
Read Code Data
5V
H
L
H
(2)
Write Lock Bit 1
6.5V
H
L
Write Lock Bit 2
6.5V
H
L
Write Lock Bit 3
6.5V
H
L
Read Lock Bits
1, 2, 3
5V
H
L
6.5V
H
L
Read Atmel ID
5V
H
L
H
H
L
L
L
L
L
1EH
X
XX 0000
00H
Read Device ID
5V
H
L
H
H
L
L
L
L
L
55H
X
XX 0001
00H
Read Device ID
5V
H
L
H
H
L
L
L
L
L
06H
X
XX 0010
00H
(2)
(2)
H
(3)
Chip Erase
Notes:
1.
2.
3.
4.
Write Code Data requires a 200 ns PROG pulse.
Write Lock Bits requires a 100 µs PROG pulse.
Chip Erase requires a 200 ns - 500 ns PROG pulse.
RDY/BSY signal is output on P3.0 during programming.
23
1921B–MICRO–09/02
Figure 13. Programming the Flash Memory
4.5V to 5.5V
AT89C55WD
ADDR.
0000H/4FFFH
A0 - A7
A8 - A13
A14*
SEE FLASH
PROGRAMMING
MODES TABLE
P1.0 - P1.7
VCC
P2.0 - P2.5
P3.4
P2.6
P2.7
P3.3
P3.6
P0
PGM
DATA
ALE
PROG
EA
VIH /VPP
P3.7
XTAL2
3 - 33 MHz
XTAL1
GND
P3.0
RDY/
BSY
RST
VIH
PSEN
Figure 14. Verifying the Flash Memory
4.5V to 5.5V
AT89C55WD
A0 - A7
ADDR.
0000H/4FFFH
P1.0 - P1.7
VCC
P2.0 - P2.5
P3.4
P2.6
P2.7
P3.3
P3.6
P3.7
P0
A8 - A13
A14*
SEE FLASH
PROGRAMMING
MODES TABLE
PGM DATA
(USE 10K
PULL-UPS)
ALE
VIH
XTAL 2
EA
XTAL1
RST
3 - 33 MHz
GND
Note:
24
VIH
PSEN
*Programming address line A14 (P3.4) is not the same as the external memory address line
A14 (P2.6).
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Flash Programming and Verification Characteristics
TA = 20°C to 30°C, VCC = 4.5V to 5.5V
Symbol
Parameter
Min
Max
Units
VPP
Programming Supply Voltage
11.5
12.5
V
IPP
Programming Supply Current
10
mA
ICC
VCC Supply Current
30
mA
1/tCLCL
Oscillator Frequency
33
MHz
tAVGL
Address Setup to PROG Low
48tCLCL
tGHAX
Address Hold After PROG
48tCLCL
tDVGL
Data Setup to PROG Low
48tCLCL
tGHDX
Data Hold After PROG
48tCLCL
tEHSH
P2.7 (ENABLE) High to VPP
48tCLCL
tSHGL
VPP Setup to PROG Low
10
µs
tGHSL
VPP Hold After PROG
10
µs
tGLGH
PROG Width
0.2
tAVQV
Address to Data Valid
48tCLCL
tELQV
ENABLE Low to Data Valid
48tCLCL
tEHQZ
Data Float After ENABLE
tGHBL
PROG High to BUSY Low
1.0
µs
tWC
Byte Write Cycle Time
80
µs
3
0
1
µs
48tCLCL
25
1921B–MICRO–09/02
Flash Programming and Verification Waveforms
PROGRAMMING
ADDRESS
P1.0 - P1.7
P2.0 - P2.5
P3.4
VERIFICATION
ADDRESS
tAVQV
PORT 0
DATA IN
tAVGL
tDVGL
tGHDX
DATA OUT
tGHAX
ALE/PROG
tSHGL
tGLGH
VPP
tGHSL
LOGIC 1
LOGIC 0
EA/VPP
tEHSH
tEHQZ
tELQV
P2.7
(ENABLE)
tGHBL
P3.0
(RDY/BSY)
BUSY
READY
tWC
Lock Bit Programming
Test Conditions
Setup
Lockbit_1, 2 or 3
Data Setup
100 µs
ALE/PROG
VCC = 6.5V
VCC = 4.5V to 5.5V
Wait 10 ms to reload
new lock bit status
26
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Parallel Chip Erase Mode
Test Conditions
Setup
Test Conditions Setup
200 ns
200 ns
ALE/PROG
P3<0>
Erase
DC
Erase
Erase
DC
Erase
VCC = 4.5V to 5.5V
VCC = 6.5V
Wait 10 ms before
reprogramming
10 ms
27
1921B–MICRO–09/02
Absolute Maximum Ratings*
Operating Temperature.................................. -55°C to +125°C
*NOTICE:
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin
with Respect to Ground .....................................-1.0V to +7.0V
Maximum Operating Voltage ............................................ 6.6V
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
DC Output Current...................................................... 15.0 mA
DC Characteristics
The values shown in this table are valid for TA = -40°C to 85°C and VCC = 4.0V to 5.5V, unless otherwise noted.
Symbol
Parameter
Condition
Min
Max
Units
VIL
Input Low Voltage
(Except EA)
-0.5
0.2 VCC -0.1
V
VIL1
Input Low Voltage (EA)
-0.5
0.2 VCC -0.3
V
VIH
Input High Voltage
0.2 V CC+0.9
VCC+0.5
V
VIH1
Input High Voltage
0.7 V CC
VCC+0.5
V
IOL = 1.6 mA
0.45
V
IOL = 3.2 mA
0.45
V
(Except XTAL1, RST)
(XTAL1, RST)
(1)
VOL
Output Low Voltage
VOL1
Output Low Voltage(1) (Port 0, ALE, PSEN)
VOH
Output High Voltage
(Ports 1,2,3, ALE, PSEN)
(Ports 1,2,3)
IOH = -60 µA, VCC = 5V ± 10%
2.4
V
IOH = -25 µA
0.75 VCC
V
IOH = -10 µA
0.9 V CC
V
2.4
V
IOH = -300 µA
0.75 VCC
V
IOH = -80 µA
0.9 V CC
V
IOH = -800 µA, V CC = 5V ± 10%
VOH1
Output High Voltage
(Port 0 in External Bus Mode)
IIL
Logical 0 Input Current (Ports 1,2,3)
VIN = 0.45V
-50
µA
ITL
Logical 1 to 0 Transition Current (Ports 1,2,3)
VIN = 2V, VCC = 5V ± 10%
-650
µA
ILI
Input Leakage Current (Port 0, EA)
0.45 < VIN < V CC
±10
µA
RRST
Reset Pulldown Resistor
30
kΩ
CIO
Pin Capacitance
Test Freq. = 1 MHz, TA = 25°C
10
pF
Active Mode, 12 MHz
25
mA
Idle Mode, 12 MHz
6.5
mA
VCC = 5.5V
100
µA
10
Power Supply Current
ICC
Power-down Mode
Notes:
28
(1)
1. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin: 10 mA
Maximum IOL per 8-bit port:
Port 0: 26 mA
Ports 1, 2, 3: 15 mA
Maximum total IOL for all output pins: 71 mA
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test conditions.
2. Minimum VCC for Power-down is 2V.
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
AC
Characteristics
Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF;
load capacitance for all other outputs = 80 pF.
External Program and Data Memory Characteristics
12 MHz Oscillator
Variable Oscillator
Min
Min
Max
Units
0
33
MHz
Symbol
Parameter
Max
1/tCLCL
Oscillator Frequency
tLHLL
ALE Pulse Width
127
2tCLCL-40
ns
tAVLL
Address Valid to ALE Low
43
tCLCL-25
ns
tLLAX
Address Hold After ALE Low
48
tCLCL-25
ns
tLLIV
ALE Low to Valid Instruction In
tLLPL
ALE Low to PSEN Low
43
tCLCL-25
ns
tPLPH
PSEN Pulse Width
205
3tCLCL-45
ns
tPLIV
PSEN Low to Valid Instruction In
tPXIX
Input Instruction Hold After PSEN
tPXIZ
Input Instruction Float After PSEN
tPXAV
PSEN to Address Valid
tAVIV
Address to Valid Instruction In
312
5tCLCL-80
ns
tPLAZ
PSEN Low to Address Float
10
10
ns
tRLRH
RD Pulse Width
400
6tCLCL-100
ns
tWLWH
WR Pulse Width
400
6tCLCL-100
ns
tRLDV
RD Low to Valid Data In
tRHDX
Data Hold After RD
tRHDZ
Data Float After RD
97
2tCLCL-28
ns
tLLDV
ALE Low to Valid Data In
517
8tCLCL-150
ns
tAVDV
Address to Valid Data In
585
9tCLCL-165
ns
tLLWL
ALE Low to RD or WR Low
200
3tCLCL+50
ns
tAVWL
Address to RD or WR Low
203
4tCLCL-75
ns
tQVWX
Data Valid to WR Transition
23
tCLCL-30
ns
tQVWH
Data Valid to WR High
433
7tCLCL-130
ns
tWHQX
Data Hold After WR
33
tCLCL-25
ns
tRLAZ
RD Low to Address Float
tWHLH
RD or WR High to ALE High
233
4tCLCL-65
145
0
3tCLCL-60
0
59
75
tCLCL-8
0
5tCLCL-90
3tCLCL-50
0
43
123
tCLCL-25
ns
ns
0
300
ns
ns
tCLCL-25
252
ns
ns
ns
0
ns
tCLCL+25
ns
29
1921B–MICRO–09/02
External Program Memory Read Cycle
tLHLL
ALE
tAVLL
tLLIV
tLLPL
tPLIV
PSEN
tPXAV
tPLAZ
tPXIZ
tLLAX
tPXIX
A0 - A7
PORT 0
tPLPH
INSTR IN
A0 - A7
tAVIV
A8 - A15
PORT 2
A8 - A15
External Data Memory Read Cycle
tLHLL
ALE
tWHLH
PSEN
tLLDV
tRLRH
tLLWL
RD
tLLAX
tAVLL
PORT 0
tRLDV
tRLAZ
A0 - A7 FROM RI OR DPL
tRHDZ
tRHDX
DATA IN
A0 - A7 FROM PCL
INSTR IN
tAVWL
tAVDV
PORT 2
30
P2.0 - P2.7 OR A8 - A15 FROM DPH
A8 - A15 FROM PCH
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
External Data Memory Write Cycle
tLHLL
ALE
tWHLH
PSEN
tLLWL
WR
tAVLL
tLLAX
tQVWX
A0 - A7 FROM RI OR DPL
PORT 0
tWLWH
tQVWH
DATA OUT
tWHQX
A0 - A7 FROM PCL
INSTR IN
tAVWL
PORT 2
P2.0 - P2.7 OR A8 - A15 FROM DPH
A8 - A15 FROM PCH
External Clock Drive Waveforms
tCHCX
VCC - 0.5V
tCHCX
tCLCH
tCHCL
0.7 VCC
0.2 VCC - 0.1V
0.45V
tCLCX
tCLCL
External Clock Drive
Symbol
Parameter
Min
Max
Units
1/tCLCL
Oscillator Frequency
0
33
MHz
tCLCL
Clock Period
30
ns
tCHCX
High Time
12
ns
tCLCX
Low Time
12
ns
tCLCH
Rise Time
5
ns
tCHCL
Fall Time
5
ns
31
1921B–MICRO–09/02
Serial Port Timing: Shift Register Mode Test Conditions
The values in this table are valid for VCC = 4.0V to 5.5V and Load Capacitance = 80 pF.
12 MHz Osc
Variable Oscillator
Symbol
Parameter
Min
Max
Min
Max
tXLXL
Serial Port Clock Cycle Time
1.0
12tCLCL
µs
tQVXH
Output Data Setup to Clock Rising Edge
700
10tCLCL-133
ns
tXHQX
Output Data Hold After Clock Rising Edge
50
2tCLCL-80
ns
tXHDX
Input Data Hold After Clock Rising Edge
0
0
ns
tXHDV
Clock Rising Edge to Input Data Valid
700
Units
10tCLCL-133
ns
Shift Register Mode Timing Waveforms
INSTRUCTION
ALE
0
1
2
3
4
5
6
7
8
tXLXL
CLOCK
tQVXH
tXHQX
WRITE TO SBUF
0
1
2
CLEAR RI
4
5
6
tXHDX
tXHDV
OUTPUT DATA
3
VALID
VALID
VALID
7
SET TI
VALID
VALID
VALID
VALID
VALID
SET RI
INPUT DATA
AC Testing Input/Output Waveforms(1)
VCC - 0.5V
0.2 VCC + 0.9V
TEST POINTS
0.2 VCC - 0.1V
0.45V
Note:
1. AC Inputs during testing are driven at VCC - 0.5V for a logic 1 and 0.45V for a logic 0. Timing measurements are made at VIH
min. for a logic 1 and VIL max. for a logic 0.
Float Waveforms(1)
V LOAD+
0.1V
V LOAD -
32
0.1V
V OL +
0.1V
Timing Reference
Points
V LOAD
Note:
V OL -
0.1V
1. For timing purposes, a port pin is no longer floating when a 100 mV change from load voltage occurs. A port pin begins to
float when a 100 mV change from the loaded VOH/VOL level occurs.
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
Ordering Information
Speed
(MHz)
Power
Supply
24
4.0V to 5.5V
33
4.5V to 5.5V
Ordering Code
Package
Operation Range
AT89C55WD-24AC
AT89C55WD-24JC
AT89C55WD-24PC
44A
44J
40P6
Commercial
(0°C to 70°C)
AT89C55WD-24AI
AT89C55WD-24JI
AT89C55WD-24PI
44A
44J
40P6
Industrial
(-40°C to 85°C)
AT89C55WD-33AC
AT89C55WD-33JC
AT89C55WD-33PC
44A
44J
40P6
Commercial
(0°C to 70°C)
Package Type
44A
44-lead, Thin Plastic Gull Wing Quad Flatpack (TQFP)
44J
44-lead, Plastic J-leaded Chip Carrier (PLCC)
40P6
40-pin, 0.600" Wide, Plastic Dual Inline Package (PDIP)
33
1921B–MICRO–09/02
Package Information
44A – TQFP
PIN 1
B
PIN 1 IDENTIFIER
E1
e
E
D1
D
C
0˚~7˚
A1
A2
A
L
COMMON DIMENSIONS
(Unit of Measure = mm)
Notes:
1. This package conforms to JEDEC reference MS-026, Variation ACB.
2. Dimensions D1 and E1 do not include mold protrusion. Allowable
protrusion is 0.25 mm per side. Dimensions D1 and E1 are maximum
plastic body size dimensions including mold mismatch.
3. Lead coplanarity is 0.10 mm maximum.
SYMBOL
MIN
NOM
MAX
A
–
–
1.20
A1
0.05
–
0.15
A2
0.95
1.00
1.05
D
11.75
12.00
12.25
D1
9.90
10.00
10.10
E
11.75
12.00
12.25
E1
9.90
10.00
10.10
B
0.30
–
0.45
C
0.09
–
0.20
L
0.45
–
0.75
e
NOTE
Note 2
Note 2
0.80 TYP
10/5/2001
R
34
2325 Orchard Parkway
San Jose, CA 95131
TITLE
44A, 44-lead, 10 x 10 mm Body Size, 1.0 mm Body Thickness,
0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP)
DRAWING NO.
REV.
44A
B
AT89C55WD
1921B–MICRO–09/02
AT89C55WD
44J – PLCC
1.14(0.045) X 45˚
PIN NO. 1
1.14(0.045) X 45˚
0.318(0.0125)
0.191(0.0075)
IDENTIFIER
E1
D2/E2
B1
E
B
e
A2
D1
A1
D
A
0.51(0.020)MAX
45˚ MAX (3X)
COMMON DIMENSIONS
(Unit of Measure = mm)
Notes:
1. This package conforms to JEDEC reference MS-018, Variation AC.
2. Dimensions D1 and E1 do not include mold protrusion.
Allowable protrusion is .010"(0.254 mm) per side. Dimension D1
and E1 include mold mismatch and are measured at the extreme
material condition at the upper or lower parting line.
3. Lead coplanarity is 0.004" (0.102 mm) maximum.
SYMBOL
MIN
NOM
MAX
A
4.191
–
4.572
A1
2.286
–
3.048
A2
0.508
–
–
D
17.399
–
17.653
D1
16.510
–
16.662
E
17.399
–
17.653
E1
16.510
–
16.662
D2/E2
14.986
–
16.002
B
0.660
–
0.813
B1
0.330
–
0.533
e
NOTE
Note 2
Note 2
1.270 TYP
10/04/01
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
44J, 44-lead, Plastic J-leaded Chip Carrier (PLCC)
DRAWING NO.
REV.
44J
B
35
1921B–MICRO–09/02
40P6 – PDIP
D
PIN
1
E1
A
SEATING PLANE
A1
L
B
B1
e
E
0º ~ 15º
C
COMMON DIMENSIONS
(Unit of Measure = mm)
REF
SYMBOL
eB
Notes:
1. This package conforms to JEDEC reference MS-011, Variation AC.
2. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
MIN
NOM
MAX
A
–
–
4.826
A1
0.381
–
–
D
52.070
–
52.578
E
15.240
–
15.875
E1
13.462
–
13.970
B
0.356
–
0.559
B1
1.041
–
1.651
L
3.048
–
3.556
C
0.203
–
0.381
eB
15.494
–
17.526
e
NOTE
Note 2
Note 2
2.540 TYP
09/28/01
R
36
2325 Orchard Parkway
San Jose, CA 95131
TITLE
40P6, 40-lead (0.600"/15.24 mm Wide) Plastic Dual
Inline Package (PDIP)
DRAWING NO.
40P6
REV.
B
AT89C55WD
1921B–MICRO–09/02
Atmel Headquarters
Atmel Operations
Corporate Headquarters
Memory
2325 Orchard Parkway
San Jose, CA 95131
TEL 1(408) 441-0311
FAX 1(408) 487-2600
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e-mail
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Web Site
http://www.atmel.com
© Atmel Corporation 2002.
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty
which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors
which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does
not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted
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MCS ®-51 is a registered trademark of Intel Corporation.
Other terms and product names may be the trademarks of others.
Printed on recycled paper.
1921B–MICRO–09/02
xM