AM186ES Advanced Micro Devices, AM186ES Datasheet - Page 163

• Manufacturer Part Number: AM186ES
• Description: microcontrollers provide a low-cost/ high-performance solution for embedded system designers who wish to use the x86 architecture.
• Manufacturer: Advanced Micro Devices

11.2
Table 11-2
11.2.1
11.2.2
Figure 11-2
15
PIO MODE REGISTERS
Table 11-2 shows the possible settings for the PIO Mode and PIO Direction bits. The
Am186ES and Am188ES microcontrollers default the 32 PIO pins to either 00b (normal
operation) or 01b (PIO input with weak internal pullup or pulldown enabled).
Pins that default to active High outputs at reset are pulled down. All other pins are pulled
up or are normal operation. See Table 11-2. The column titled Power-On Reset State in
Table 11-1 lists the defaults for the PIOs.
The internal pullup resistor has a value of approximately 10 Kohms. The internal pulldown
resistor has a value of approximately 10 Kohms.
PIO Mode and PIO Direction Settings
PIO Mode 1 Register (PIOMODE1, Offset 76h)
The value of PIOMODE1 at reset is 0000h.
Bits 15–0: PIO Mode Bits (PMODE31–PMODE16)—This field, along with the PIO direction
registers, determines whether each PIO pin performs its preassigned function or is enabled
as a custom PIO signal. The most significant bit of the PMODE field determines whether
PIO31 is enabled, the next bit determines whether PIO30 is enabled, and so on.
Table 11-2 shows the values that the PIO mode bits and the PIO direction bits can encode.
PIO Mode 0 Register (PIOMODE0, Offset 70h)
The value of PIOMODE0 at reset is 0000h.
Bits 15–0: PIO Mode Bits (PMODE15–PMODE0)—This field is a continuation of the
PMODE field in the PIO Mode 1 register.
PIO Mode 1 Register
(PIOMODE1, offset 76h)
PMODE (31–16)
Mode
PIO
0
0
1
1
7
Direction Pin Function
PIO
0
1
0
1
Normal operation
PIO input with pullup/pulldown
PIO output
PIO input w/o pullup/pulldown
Programmable I/O Pins
0
Figure 11-3
15
PIO Mode 0 Register
(PIOMODE0, offset 70h)
PMODE (15–0)
7
0
11-3