AMD Am186 CC User Manual page 71

Table 3-7 Signal Descriptions (Continued)
Multiplexed
1
Signal Name
Signal(s)
PROGRAMMABLE I/O (PIOS)
(For a list of the
multiplexed
PIO47–PIO0 signals ordered
by PIO number,
see Table 3-2.)
PROGRAMMABLE TIMERS
[INT8]
[PWD]
PIO6
System Overview
Type Description
Shared Programmable I/O pins can be programmed with the
following attributes: PIO function (enabled/disabled), direction
(input/output), and weak pullup or pulldown.
After a reset, the PIO pins default to various configurations. Most
of the PIO pins are configured as PIO inputs with pullup after
reset. The system initialization code must reconfigure any PIO
pins as required.
PIO5, PIO15, PIO27, PIO29, PIO30, and PIO33–PIO35 are
capable of generating an interrupt on the shared interrupt
B
channel 14.
The multiplexed signals PIO8/ARDY, PIO13/PCS0,
PIO14/PCS1, PIO15/WR, PIO29/DT/R, PIO30/DEN,
PIO33/ALE, PIO34/BHE, and PIO35/SRDY default to non-PIO
operation at reset.
The following PIO signals are multiplexed with alternate signals
that can be used by emulators: PIO8, PIO15, PIO33, PIO34, and
PIO35. Consider any emulator requirements for the alternate
signals before using these pins as PIOs.
Pulse-Width Demodulator: If pulse-width demodulation is
enabled, [PWD] processes a signal through the Schmitt trigger
input. [PWD] is used internally to drive [TMRIN0] and [INT8], and
[PWD] is inverted internally to drive [TMRIN1] and an additional
internal interrupt. If interrupts are enabled and Timer 0 and Timer
1 are properly configured, the pulse width of the alternating
[PWD] signal can be calculated by comparing the values in Timer
0 and Timer 1.
STI
In PWD mode, the signals [TMRIN0]/PIO27 and [TMRIN1]/PIO0
can be used as PIOs. If they are not used as PIOs they are
ignored internally.
The additional internal interrupt used in PWD mode uses the
same interrupt channel as [INT7]. If [INT7] is used, it must be
assigned to the shared interrupt channel.
Am186™CC/CH/CU Microcontrollers User's Manual 3-21