C5535 TIMCNT1 register access (write) while timer is running

Hi Nicolas,

It is not possible to write to the Timer Counter Register ever.

The way to put a new value into the TIMCNT1 is to write TIMPRD1 with the value desired, then clear the START bit of TCR to stop the countdown, then set the START bit of TCR to load value from TIMPRD1 into TIMCNT1 and start the counter counting down again.

Similarly, I believe you could modify the TIMPRD1 during timer execution, then with autoreload mode enabled, the timer will load the new value into TIMCNT1 after the timer counts down and autoreloads.

See Section 5.2.2 Using the 32-bit General Purpose Timer in the C5535 Technical Reference Manual:

When the START bit is set to 1 in the TCR, the contents of the Timer Period Registers (TIMPRD1 and
TIMPRD2) are loaded into the concatenated Timer Counter Registers (TIMCNT1 and TIMCNT2) and the
timer starts to count down with every cycle of the prescale divided clock. When TIMCNT1 and TIMCNT2
reach 0, the timer sends an interrupt request (TINT) to the CPU and a DMA event to the four DMAs.

Hope this helps,
Mark