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5.11 Timer Interrupts

5.11.2 Programmable Frequency Timer Interrupts

A multi-function programmable 16-bit counter/timer is provided by the SCN68681 DUART. The counter/timer (C/T) operating modes and clock sources are programmed in the ACR[6:4] field.

In the counter mode, the C/T counts down the number of pulses loaded into CTUR and CTLR by the MPU. Upon reaching terminal count 000016, the counter ready status bit (ISR[3]) is set.

In the timer mode, the C/T generates a square wave with a period of twice the value (in clock periods) of the CTUR and CTLR. In this mode the C/T runs continuously. The counter ready status bit (ISR[3]) is set once each cycle of the square wave.

The counter ready status bit ISR[3] bit can be read and cleared. Interrupts will be generated when the counter ready status bit ISR[3] is a '1' and the interrupt mask register bit IMR[3] is a '1'.

CC175 - Dual Channel Intelligent CAN Interface for VMEbus - 30 SEP 1996
Copyright © 1996 Compcontrol, Inc.

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