Am186™CC/CH/CU Microcontrollers User’s Manual
9-1
CHAPTER
9
PROGRAMMABLE I/O SIGNALS
9.1
OVERVIEW
The Am186CC/CH/CU microcontrollers provide 48 user-programmable input/output
signals (PIOs).
Many of these signals share a pin with at least one alternate function. If an application does
not need the alternate function, the associated PIO can be programmed through the PIO
registers.
If a pin is enabled to function as a PIO, the alternate function is disabled and does not affect
the pin. Conversely, the value of any pin configured as a PIO does not affect the alternate
function of the pin. When configured as a PIO, an appropriate default value for the signal
is sent to the associated device rather than the value on the pin.
A PIO can be configured to operate as an input or output, with or without internal pullup or
pulldown resistors (pullup or pulldown depends on the pin configuration and is not user-
configurable), or as an open-drain output. Additionally, eight PIOs can be configured as
external interrupt sources. For information on this interrupt functionality, see Chapter 7,
“Interrupts.”
Associated bits in the PIO Mode, PIO Direction, PIO Data, PIO Set, and PIO Clear registers
control each of the 48 PIOs. Because these registers are 16 bits wide, each PIO function
requires three registers (see Table 9-2). Two additional registers are provided for ease of
use.
9.2
BLOCK DIAGRAM
Figure 9-1 shows the PIO operation.
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...