Programmable Interval Timer
Élan™SC520 Microcontroller User’s Manual
16-7
■
Driving an external 1.19318-MHz clock on the CLKTIMER pin—A system designer can
choose to supply an external clock source frequency of 1.19318 MHz on the CLKTIMER
pin. This pin must be specifically configured for this functionality by the system boot
code during the system boot process, prior to configuring the PIT. The CLK_PIN_DIR
bit in the Clock Select (CLKSEL) register (MMCR offset C26h) is used for this purpose.
16.6
INITIALIZATION
At system reset, the state of the PIT itself is undefined. The mode, count value, and output
of all channels are undefined. Each PIT channel must be programmed before it can be
used. To prevent superfluous interrupts, each PIT channel must be configured prior to
enabling interrupts on the Am5
x
86 CPU.
1. Write a control word into the PIT Mode Control (PITMODECTL) register (Port 0043h).
2. Write an initial count into the PIT Channel x Count (PITxCNT) register of the PIT channel
being programmed. The control word determines the format of the initial count.
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...