Samsung 8-Bit CMOS Microcontroller, S3C9228/P9228 user manual Function Description

S3C9228/P9228 TIMER 1

FUNCTION DESCRIPTION

Interval Timer Function (Timer A and Timer B)

The timer A and B module can generate an interrupt: the timer A match interrupt (TAINT) and the timer B match interrupt (TBINT).

The timer A match interrupt pending condition (INTPND2.0) and the timer B match interrupt pending condition (INTPND2.1) must be cleared by software in the application's interrupt service by means of writing a "0" to the INTPND2.0 and INTPND2.1 interrupt pending bit.

Even though TAINT and TBINT are disabled, the application's service routine can detect a pending condition of TAINT and TBINT by the software and execute it's sub-routine. When this case is used, the TAINT and TBINT pending bit must be cleared by the application sub-routine by writing a "0" to the corresponding pending bit INTPND2.0 and INTPND2.1.

In interval timer mode, a match signal is generated when the counter value is identical to the values written to the timer A or timer B reference data registers, TADATA or TBDATA. The match signal generates corresponding match interrupt and clears the counter.

If, for example, you write the value 20H to TADATA and 0EH to TACON, the counter will increment until it reaches 20H. At this point, the timer A interrupt request is generated, the counter value is cleared, and counting resumes and you write the value 10H to TBDATA, "0" to TACON.7, and 0EH to TBCON, the counter will increment until it reaches 10H. At this point, TB interrupt request is generated, the counter value is cleared and counting resumes.

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