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P87C554SFAA,512

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66P67-P69P70-P72P73-P75P76-P77
Philips Semiconductors Product data
P87C554
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
2
C, PWM,
capture/compare, high I/O
2002 Mar 25
8
OSCILLATOR CHARACTERISTICS
XTAL1 and XTAL2 are the input and output, respectively, of an
inverting amplifier. The pins can be configured for use as an on-chip
oscillator, as shown in the logic symbol.
To drive the device from an external clock source, XTAL1 should be
driven while XTAL2 is left unconnected. There are no requirements
on the duty cycle of the external clock signal, because the input to
the internal clock circuitry is through a divide-by-two flip-flop.
However, minimum and maximum high and low times specified in
the data sheet must be observed.
RESET
A reset is accomplished by either (1) externally holding the RST pin
high for at least two machine cycles (24 oscillator periods) or (2)
internally by an on-chip power-on detect (POD) circuit which detects
V
CC
ramping up from 0 V.
To insure a good external power-on reset, the RST pin must be high
long enough for the oscillator to start up (normally a few
milliseconds) plus two machine cycles. The voltage on V
DD
and the
RST pin must come up at the same time for a proper startup.
For a successful internal power-on reset, the V
CC
voltage must
ramp up from 0 V smoothly at a ramp rate greater than 5 V/100 ms.
The RST line can also be pulled HIGH internally by a pull-up
transistor activated by the watchdog timer T3. The length of the
output pulse from T3 is 3 machine cycles. A pulse of such short
duration is necessary in order to recover from a processor or system
fault as fast as possible.
Note that the short reset pulse from Timer T3 cannot discharge the
power-on reset capacitor (see Figure 2). Consequently, when the
watchdog timer is also used to set external devices, this capacitor
arrangement should not be connected to the RST pin, and a
different circuit should be used to perform the power-on reset
operation. A timer T3 overflow, if enabled, will force a reset condition
to the P87C554 by an internal connection, independent of the level
of the RST pin.
A reset may be performed in software by setting the software reset
bit, SRST (AUXR1.5).
V
DD
R
RST
RST
SCHMITT
TRIGGER
RESET
CIRCUITRY
ON-CHIP
RESISTOR
OVERFLOW
TIMER T3
SU00952
Figure 1. On-Chip Reset Configuration
R
RST
V
DD
V
DD
+
2.2 µF
P87C554
RST
SU01649
Figure 2. Power-On Reset
LOW POWER MODES
Stop Clock Mode
The static design enables the clock speed to be reduced down to
0 MHz (stopped). When the oscillator is stopped, the RAM and
Special Function Registers retain their values. This mode allows
step-by-step utilization and permits reduced system power
consumption by lowering the clock frequency down to any value. For
lowest power consumption the Power Down mode is suggested.
Idle Mode
In the idle mode (see Table 2), the CPU puts itself to sleep while
some of the on-chip peripherals stay active. The instruction to
invoke the idle mode is the last instruction executed in the normal
operating mode before the idle mode is activated. The CPU
contents, the on-chip RAM, and all of the special function registers
remain intact during this mode. The idle mode can be terminated
either by any enabled interrupt (at which time the process is picked
up at the interrupt service routine and continued), or by a hardware
reset which starts the processor in the same manner as a power-on
reset.
Power-Down Mode
To save even more power, a Power Down mode (see Table 2) can
be invoked by software. In this mode, the oscillator is stopped and
the instruction that invoked Power Down is the last instruction
executed. The on-chip RAM and Special Function Registers retain
their values down to 2.0 V and care must be taken to return V
CC
to
the minimum specified operating voltages before the Power Down
Mode is terminated.
Either a hardware reset or external interrupt can be used to exit from
Power Down. The Wake-up from Power-down bit, WUPD (AUXR1.3)
must be set in order for an external interrupt to cause a wake-up
from power-down. Reset redefines all the SFRs but does not
change the on-chip RAM. An external interrupt allows both the SFRs
and the on-chip RAM to retain their values.
To properly terminate Power Down the reset or external interrupt
should not be executed before V
CC
is restored to its normal
operating level and must be held active long enough for the
oscillator to restart and stabilize (normally less than 10 ms).
Philips Semiconductors Product data
P87C554
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
2
C, PWM,
capture/compare, high I/O
2002 Mar 25
9
Table 2. External Pin Status During Idle and Power-Down Modes
MODE
PROGRAM
MEMORY
ALE PSEN PORT 0 PORT 1 PORT 2 PORT 3 PORT 4
PWM0/
PWM1
Idle Internal 1 1 Data Data Data Data Data High
Idle External 1 1 Float Data Address Data Data High
Power-down Internal 0 0 Data Data Data Data Data High
Power-down External 0 0 Float Data Data Data Data High
With an external interrupt, INT0 and INT1 must be enabled and
configured as level-sensitive. Holding the pin low restarts the oscillator
but bringing the pin back high completes the exit. Once the interrupt
is serviced, the next instruction to be executed after RETI will be the
one following the instruction that put the device into Power Down.
POWER OFF FLAG
The Power Off Flag (POF) is set by on-chip circuitry when the V
CC
level on the P87C554 rises from 0 to 5 V. The POF bit can be set or
cleared by software allowing a user to determine if the reset is the
result of a power-on or a warm start after powerdown. The V
CC
level
must remain above 3 V for the POF to remain unaffected by the V
CC
level.
Design Consideration
• When the 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 when Idle is terminated by
reset, the instruction following the one that invokes Idle should not
be one that writes to a port pin or to external memory.
ONCE Mode
The ONCE (“On-Circuit Emulation”) Mode facilitates testing and
debugging of systems without the device having to be removed from
the circuit. The ONCE Mode is invoked by:
1. Pull ALE low while the device is in reset and PSEN
is high;
2. Hold ALE low as RST is deactivated.
While the device is in ONCE Mode, the Port 0 pins go into a float
state, and the other port pins and ALE and PSEN
are weakly pulled
high. The oscillator circuit remains active. While the device is in this
mode, an emulator or test CPU can be used to drive the circuit.
Normal operation is restored when a normal reset is applied.
Reduced EMI Mode
The ALE-Off bit, AO (AUXR.0) can be set to disable the ALE output.
It will automatically become active when required for external
memory accesses and resume to the OFF state after completing the
external memory access.
If logic 1s are written to PD and IDL at the same time, PD takes precedence. The reset value of PCON is (00X00000).
SU00954
IDL
BIT SYMBOL FUNCTION
PCON.7 SMOD1 Double Baud rate bit. When set to logic 1, the baud rate is doubled when the serial port SIO0 is being
used in modes 1, 2, or 3.
PCON.6 SMOD0 Selects SM0/FE for SCON.7 bit.
PCON.5 POF Power Off Flag
PCON.4 WLE Watchdog Load Enable. This flag must be set by software prior to loading timer T3 (watchdog timer). It is
cleared when timer T3 is loaded.
PCON.3 GF1 General-purpose flag bit.
PCON.2 GF0 General-purpose flag bit.
PCON.1 PD Power-down bit. Setting this bit activates the power-down mode. It can only be set if input EW
is high.
PCON.0 IDL Idle mode bit. Setting this bit activates the Idle mode.
PDGF0GF1WLEPOFSMOD0SMOD1
01234567
(LSB)(MSB)
PCON
(87H)
Figure 3. Power Control Register (PCON)
Philips Semiconductors Product data
P87C554
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
2
C, PWM,
capture/compare, high I/O
2002 Mar 25
10
Expanded Data RAM Addressing
The P87C554 has internal data memory that is mapped into four
separate segments: the lower 128 bytes of RAM, upper 128 bytes of
RAM, 128 bytes Special Function Register (SFR), and 256 bytes
expanded RAM (EXTRAM).
The four segments are:
1. The Lower 128 bytes of RAM (addresses 00H to 7FH) are
directly and indirectly addressable.
2. The Upper 128 bytes of RAM (addresses 80H to FFH) are
indirectly addressable only.
3. The Special Function Registers, SFRs, (addresses 80H to FFH)
are directly addressable only.
4. The 256-bytes expanded RAM (ERAM, 00H – FFH) are indirectly
accessed by move external instruction, MOVX, and with the
EXTRAM bit cleared, see Figure 4.
The Lower 128 bytes can be accessed by either direct or indirect
addressing. The Upper 128 bytes can be accessed by indirect
addressing only. The Upper 128 bytes occupy the same address
space as the SFR. That means they have the same address, but are
physically separate from SFR space.
When an instruction accesses an internal location above address
7FH, the CPU knows whether the access is to the upper 128 bytes
of data RAM or to SFR space by the addressing mode used in the
instruction. Instructions that use direct addressing access SFR
space. For example:
MOV 0A0H,#data
accesses the SFR at location 0A0H (which is P2). Instructions that
use indirect addressing access the Upper 128 bytes of data RAM.
For example:
MOV @R0,#data
where R0 contains 0A0H, accesses the data byte at address 0A0H,
rather than P2 (whose address is 0A0H).
The ERAM can be accessed by indirect addressing, with EXTRAM
bit cleared and MOVX instructions. This part of memory is physically
located on-chip, logically occupies the first 256-bytes of external
data memory.
With EXTRAM = 0, the EXTRAM is indirectly addressed, using the
MOVX instruction in combination with any of the registers R0, R1 of
the selected bank or DPTR. An access to ERAM will not affect ports
P0, P3.6 (WR#) and P3.7 (RD#). P2 SFR is output during expanded
RAM addressing. For example, with EXTRAM = 0,
MOVX @R0,#data
where R0 contains 0A0H, accesses the ERAM at address 0A0H
rather than external memory. An access to external data memory
locations higher than FFH (i.e., 0100H to FFFFH) will be performed
with the MOVX DPTR instructions in the same way as in the
standard 80C51, so with P0 and P2 as data/address bus, and P3.6
and P3.7 as write and read timing signals. Refer to Figure 5.
With EXTRAM = 1, MOVX @Ri and MOVX @DPTR will be similar
to the standard 80C51. MOVX @ Ri will provide an 8-bit address
multiplexed with data on Port 0 and any output port pins can be
used to output higher order address bits. This is to provide the
external paging capability. MOVX @DPTR will generate a 16-bit
address. Port 2 outputs the high-order eight address bits (the
contents of DPH) while Port 0 multiplexes the low-order eight
address bits (DPL) with data. MOVX @Ri and MOVX @DPTR will
generate either read or write signals on P3.6 (#WR) and P3.7 (#RD).
The stack pointer (SP) may be located anywhere in the 256 bytes
RAM (lower and upper RAM) internal data memory. The stack may
not be located in the ERAM address space.
AUXR
Reset Value = xxxx x110B
— ————LVADC EXTRAM AO
Not Bit Addressable
Bit:
Symbol Function
AO Disable/Enable ALE
AO 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.
EXTRAM Internal/External RAM (00H – FFH) access using MOVX @Ri/@DPTR
EXTRAM Operating Mode
0 Internal ERAM (00H–FFH) access using MOVX @Ri/@DPTR
1 External data memory access.
LVADC Enable A/D low voltage operation
LVADC Operating Mode
0 Turns off A/D charge pump.
1 Turns on A/D charge pump. Required for operation below 4V.
— Not implemented, reserved for future use*.
NOTE:
*User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features. In that
case, the reset or inactive value of the new bit will be 0, and its active value will be 1. The value read from a reserved bit is indeterminate.
SU00979A
76543210
Address = 8EH
Figure 4. AUXR: Auxiliary Register
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66P67-P69P70-P72P73-P75P76-P77

P87C554SFAA,512

Mfr. #:
Buy P87C554SFAA,512
Manufacturer:
NXP Semiconductors
Description:
Microcontrollers - MCU 8-bit Microcontrollers - MCU 80C51 16K/512 OTP
Lifecycle:
New from this manufacturer.
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