80C652 Datasheet, PDF (9/25 Pages) NXP Semiconductors – CMOS single-chip 8-bit microcontrollers

Phlips Semiconductors
CMOS single-chip 8-bit microcontrollers
Product specification
80C652/83C652
ROM CODE PROTECTION
(83C652)
The 8XC652 has an additional security
feature. ROM code protection may be
selected by setting a mask–programmable
security bit (i.e., user dependent). This
feature may be requested during ROM code
submission. When selected, the ROM code is
protected and cannot be read out at any time
by any test mode or by any instruction in the
external program memory space.
The MOVC instructions are the only
instructions that have access to program
code in the internal or external program
memory. The EA input is latched during
RESET and is “don’t care” after RESET
(also if the security bit is not set). This
implementation prevents reading internal
program code by switching from external
program memory to internal program memory
during a MOVC instruction or any other
instruction that uses immediate data.
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,
page 2.
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
milliseconds) plus two machine cycles. At
power-on, the voltage on V_DD and RST must
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
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.
I²C Serial Communication—SIO1
The I²C serial port is identical to the I²C
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 I²C pins are alternate functions
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.
Table 2. External Pin Status During Idle and Power-Down Mode
MODE
PROGRAM
MEMORY
ALE
PSEN
PORT 0
Idle
Internal
1
1
Data
Idle
External
1
1
Float
Power-down
Internal
0
0
Data
Power-down
External
0
0
Float
PORT 1
Data
Data
Data
Data
PORT 2
Data
Address
Data
Data
PORT 3
Data
Data
Data
Data
Serial Control Register (S1CON) – See Table 3
S1CON (D8H) CR2 ENS1 STA STO SI AA CR1 CR0
Bits CR0, CR1 and CR2 determine the serial clock frequency that is generated in the master mode of operation.
Table 3. Serial Clock Rates
BIT FREQUENCY (kHz) AT f_OSC
CR2 CR1 CR0
6MHz
12MHz
16MHz
24MHz
f_OSC DIVIDED BY
0
0
0
23
47
62.5
94
256
0
0
1
27
54
71
107¹
224
0
1
0
31.25
62.5
83.3
125¹
192
0
1
1
37
75
100
150¹
160
1
0
0
6.25
12.5
17
25
960
1
0
1
50
100
133¹
200¹
120
1
1
0
100
200¹
267¹
400¹
60
1
1
1
0.24 < 62.5 0.49 < 62.5 0.65 < 55.6 0.98 < 50.0
96 × (256 – (reload value Timer 1))
0 to 255
0 to 254
0 to 253
0 to 251
reload value range Timer 1 (in mode 2)
NOTES:
1. These frequencies exceed the upper limit of 100kHz of the I²C-bus specification and cannot be used in an I²C-bus application.
1996 Aug 15
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