80C32/80C52
1 FFFH). When EA is held low, the CPU executes only out
of external Program Memory. EA must not be floated.
PSEN
Program Store Enable output is the read strobe to external
Program Memory. PSEN is activated twice each machine
cycle during fetches from external Program Memory.
(However, when executing out of external Program
Memory, two activations of PSEN are skipped during
each access to external Data Memory). PSEN is not
activated during fetches from internal Program Memory.
PSEN can sink/source 8 LS TTL inputs. It can drive
CMOS inputs without an external pullup.
XTAL1
Input to the inverting amplifier that forms the oscillator.
Receives the external oscillator signal when an external
oscillator is used.
XTAL2
Output of the inverting amplifier that forms the oscillator.
This pin should be floated when an external oscillator is
used.
EA
When EA is held high, the CPU executes out of internal
Program Memory (unless the Program Counter exceeds
Idle And Power Down Operation
Figure 3 shows the internal Idle and Power Down clock
configuration. As illustrated, Power Down operation
stops the oscillator. Idle mode operation allows the
interrupt, serial port, and timer blocks to continue to
function, while the clock to the CPU is gated off.
Symbol
Position
Name and Function
SMOD
PCON.7
Double Baud rate bit. When set to
a 1, the baud rate is doubled when
the serial port is being used in
either modes 1, 2 or 3.
(Reserved)
(Reserved)
–
–
–
GF1
GF0
PD
PCON.6
PCON.5
PCON.4
PCON.3
PCON.2
PCON.1
These special modes are activated by software via the
Special Function Register, PCON. Its hardware address is
87H. PCON is not bit addressable.
(Reserved)
General-purpose flag bit.
General-purpose flag bit.
Power Down bit. Setting this bit
activates power down operation.
Idle mode bit. Setting this bit
activates idle mode operation.
Figure 3.Idle and Power Down Hardware.
IDL
PCON.0
If 1’s are written to PD and IDL at the same time. PD
takes, precedence. The reset value of PCON is
(000X0000).
Idle Mode
The instruction that sets PCON.0 is the last instruction
executed before the Idle mode is activated. Once in the
Idle mode the CPU status is preserved in its entirety : the
Stack Pointer, Program Counter, Program Status Word,
Accumulator, RAM and all other registers maintain their
data during idle. Table 1 describes the status of the
external pins during Idle mode.
PCON : Power Control Register
(MSB)
SMOD
(LSB)
IDL
–
–
–
GF1
GF0
PD
MATRA MHS
Rev. G (14 Jan. 97)
5
TEMIC [ TEMIC SEMICONDUCTORS ]
