
Programmable I/O Pins
11-3
11.2
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.
Table 11-2
PIO Mode and PIO Direction Settings
11.2.1
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.
11.2.2
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
PIO
Direction
Pin Function
0
0
Normal operation
0
1
PIO input with pullup/pulldown
1
0
PIO output
1
1
PIO input w/o pullup/pulldown
15
7
0
PMODE (31–16)
15
7
0
PMODE (15–0)
Figure 11-3
PIO Mode 0 Register
(PIOMODE0, offset 70h)
Figure 11-2
PIO Mode 1 Register
(PIOMODE1, offset 76h)
Summary of Contents for Am186 ES
Page 1: ...Am186 ES and Am188 ES User s Manual...
Page 4: ...iv...
Page 12: ...Table of Contents xii...
Page 22: ...Features and Performance 1 8...
Page 60: ...System Overview 3 28...
Page 84: ...Chip Select Unit 5 14...
Page 132: ...Timer Control Unit 8 8...
Page 166: ...Programmable I O Pins 11 6...
Page 184: ...Register Summary A 18...