
11. PPG (Programmable Pulse Generator)
MC97F6108A User’s manual
96
11.2
PPG start and one shot pulse
PPG start sources are PPGST bit of PPGCR register and C0_FLAG (comparator 1 flag). If PPGMD is
'0', only PPGST starts the counter, if PPGMD is '1', PPGST or C0_FLAG starts the counter. After one
period, C0_FLAG is cleared automatically.
PPG period is determined by the PPGPH/PPGPL and duty is determined by PPGDH, PPGDL.
Period = ({PPGPH, PPGPL} + 1 ) X PPG Clock Period
Duty = ({PPGDH, PPGDL} + 1) X PPG Clock Period
If PPG starts counting, PPG compares PPGH/PPGL value with PPGDH/PPGDL value. If the
PPGH/PPGL value and the PPGDH/PPGDL value matches, PPG compares PPGH/PPGL value with
PPGPH/PPGPL value.
If the PPGH/PPGL value and the PPGPH/PPGPL value matches, PPG counter is cleared and does not
start again. Only start sources can start counter again. This is one shot pulse operation.
The duty value and counter matching enables the period value and counter comparison.
PPGPH/PPGPL registers are loaded to period compare register when the PPG is not operating.
PPGDH/PPGDL registers are loaded to compare registers when the PPG is not in the duty state. It is
highly recommended that the duty value is not set same to the period value.