Élan™SC520 Microcontroller User’s Manual
23-1
CHAPTER
23
PROGRAMMABLE INPUT/OUTPUT
23.1
OVERVIEW
The ÉlanSC520 microcontroller supports 32 programmable I/O signals (PIOs) that can be
used on the system board to monitor signals or control devices that are not handled by the
other functions in the ÉlanSC520 microcontroller. These signals can be programmed to be
inputs or to be driven out High or Low as outputs.
The PIO signals can be programmed for the following functions:
■
Read as inputs (default condition after reset)
■
Driven High or Low as an output
On the ÉlanSC520 microcontroller, all of the PIOs are shared with other functions that may
not be needed in every system design, e.g., GP bus signals. This is done to give system
designers the most flexibility. For clarity, throughout this document, the two functions
available on the PIO pins are distinguished from each other as the
PIO function and the
interface function.
Each of the PIO signals is terminated within the ÉlanSC520 microcontroller with either a
pullup or pulldown resistance. This feature makes system design easier by eliminating the
need for termination on the board. Each PIO signal is terminated according to the pin’s
interface function, i.e., a normally active Low signal will usually have a pullup to make it
inactive on reset. See the
Élan™SC520 Microcontroller Data Sheet, order #22003, for the
termination of each PIO signal.
23.2
BLOCK DIAGRAM
Figure 23-1 is a block diagram of the PIO feature. This structure is repeated for each of the
PIOs; only one example PIO is shown in the diagram.
Содержание Elan SC520
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Страница 28: ...Introduction xxviii lan SC520 Microcontroller User s Manual...
Страница 42: ...Architectural Overview 1 14 lan SC520 Microcontroller User s Manual...
Страница 78: ...System Initialization 3 22 lan SC520 Microcontroller User s Manual...
Страница 108: ...Clock Generation and Control 5 10 lan SC520 Microcontroller User s Manual...
Страница 118: ...Reset Generation 6 10 lan SC520 Microcontroller User s Manual...
Страница 148: ...System Arbitration 8 24 lan SC520 Microcontroller User s Manual...
Страница 214: ...SDRAM Controller 10 36 lan SC520 Microcontroller User s Manual...
Страница 230: ...Write Buffer and Read Buffer 11 16 lan SC520 Microcontroller User s Manual...
Страница 288: ...GP Bus DMA Controller 14 22 lan SC520 Microcontroller User s Manual...
Страница 316: ...Programmable Interval Timer 16 8 lan SC520 Microcontroller User s Manual...
Страница 328: ...Software Timer 18 4 lan SC520 Microcontroller User s Manual...
Страница 346: ...Real Time Clock 20 12 lan SC520 Microcontroller User s Manual...
Страница 360: ...UART Serial Ports 21 14 lan SC520 Microcontroller User s Manual...
Страница 414: ...AMDebug Technology 26 8 lan SC520 Microcontroller User s Manual...