87C654 Philips Semiconductors, 87C654 Datasheet - Page 9

• Manufacturer Part Number: 87C654
• Description: 80C51 8-bit microcontroller 8K/16K/ 256 OTP/ I2C
• Manufacturer: Philips Semiconductors

Bits CR0, CR1 and CR2 determine the serial clock frequency that is generated in the master mode of operation.
1. These frequencies exceed the upper limit of 100kHz of the I
Philips Semiconductors
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 holding the RST
pin high for at least two machine cycles (24
oscillator periods), while the oscillator is
running. To insure a good power-on reset, the
RST pin must be high long enough to allow
the oscillator time to start up (normally a few
Table 2. External Pin Status During Idle and Power-Down Mode
Serial Control Register (S1CON) – See Table 3
S1CON (D8H)
Table 3. Serial Clock Rates
NOTES:
1996 Aug 16
CR2
CMOS single-chip 8-bit microcontroller
Idle
Idle
Power-down
Power-down
CR2
0
0
0
0
1
1
1
1
MODE
ENS1
CR1
0
0
1
1
0
0
1
1
STA
CR0
STO
0
1
0
1
0
1
0
1
PROGRAM
MEMORY
External
External
Internal
Internal
0.25 < 62.5
SI
0 to 255
BIT FREQUENCY (kHz) AT f
6MHz
31.25
6.25
100
23
27
37
50
AA
milliseconds) plus two machine cycles. At
power-on, the voltage on V
come up at the same time for a proper
start-up.
Idle Mode
In the idle mode, the CPU puts itself to sleep
while all 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
In the power-down mode, the oscillator is
stopped and the instruction to invoke
ALE
0.5 < 62.5
CR1
0 to 254
12MHz
1
1
0
0
200
62.5
12.5
100
47
54
75
1
CR0
2
C-bus specification and cannot be used in an I
0.65 < 55.6
PSEN
0 to 253
16MHz
1
1
0
0
133
267
62.5
83.3
9
100
71
17
OSC
1
1
CC
and RST must
PORT 0
0.81 < 69.4
Float
Float
Data
Data
0 to 253
20MHz
104
125
166
334
89
78
21
1
1
1
1
1
power-down is the last instruction executed.
Only the contents of the on-chip RAM are
preserved. A hardware reset is the only way
to terminate the power-down mode. The
control bits for the reduced power modes are
in the special function register PCON. Table 2
shows the state of the I/O ports during low
current operating modes.
I
COMMUNICATION—SIO1
The I
serial port on the 8XC552. The operation of
this subsystem is described in detail in the
8XC552 section of this manual.
Note that in both the 8XC652/4 and the
8XC552 the I
to port pins P1.6 and P1.7. Because of this,
P1.6 and P1.7 on these parts do not have a
pull-up structure as found on the 80C51.
Therefore P1.6 and P1.7 have open drain
outputs on the 8XC652/4.
2
PORT 1
(Reload value range: 0 – 254 in mode 2)
C SERIAL
Data
Data
Data
Data
96
2
C serial port is identical to the I
(256 – (reload value Timer 1))
2
f
2
C-bus application.
OSC
C pins are alternate functions
Address
PORT 2
DIVIDED BY
Data
Data
Data
256
224
192
160
960
120
60
Product specification
87C654
PORT 3
Data
Data
Data
Data
2
C