Interrupt Cause - Renesas Hitachi H8S/2194 Series Hardware Manual

16.4

Interrupt Cause

The interrupt causes for the Timer R are 3-causes of the TMRI3 bit through TMRI1 bit of the
timer R control/status register (TMRCS).
(a) Interrupts being caused by the underflowing of the TMRU-1 (TMRI1)
These interrupts will constitute the timing for reloading with the TMRU-1.
(b) Interrupts being caused by the underflowing of the TMRU-2 or by an end of the acceleration
or braking process (TMRI2)
When interrupts occur at the reload timing of the TMRU-2, clear the AC/BR
(acceleration/braking) bit of the timer R mode register 1 (TMRM1) to 0.
(c) Interrupts being caused by the capture signals of the TMRU-3 and by ending the slow
tracking mono-multi process (TMRI3)
Since these two interrupt causes are constituting the OR, it becomes necessary to determine
which interrupt cause is occurring using the software.
Respective interrupt causes are being set to the CAPF flag or the SLW flag of the timer R
mode register 2 (TMRM2), have the software determine which.
Since the CAPF flag and the SLW flag will not be cleared automatically, program the
software to clear them. (Writing 0 only is valid for these flags.) Unless these flags are
cleared, detection of the next cause becomes unworkable. Also, if the CP/SLM bit is
changed leaving these flags un-cleared as they are, these flags will get cleared.
Rev. 2.0, 11/00, page 350 of 1037