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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
The comparison x matches when it is enabled by the bit CEN in the
(PWM_CMPMx for the comparison x) and when the counter of the channel 0 reaches
the comparison value defined by the field CV in
“PWM Comparison x Value Register”
(PWM_CMPVx for the comparison x). If the counter of the channel 0 is center aligned (CALG =
1 in
), the bit CVM (in PWM_CMPVx) defines if the comparison
is made when the counter is counting up or counting down (in left alignment mode CALG=0, this
bit is useless).
If a fault is active on the channel 0, the comparison is disabled and cannot match (see
The user can define the periodicity of the comparison x by the fields CTR and CPR (in
PWM_CMPVx). The comparison is performed periodically once every CPR+1 periods of the
counter of the channel 0, when the value of the comparison period counter CPRCNT (in
PWM_CMPMx) reaches the value defined by CTR. CPR is the maximum value of the compari-
son period counter CPRCNT. If CPR=CTR=0, the comparison is performed at each period of the
counter of the channel 0.
The comparison x configuration can be modified while the channel 0 is enabled by using the
“PWM Comparison x Mode Update Register”
(PWM_CMPMUPDx registers for the comparison
x). In the same way, the comparison x value can be modified while the channel 0 is enabled by
using the
“PWM Comparison x Value Update Register”
(PWM_CMPVUPDx registers for the
comparison x).
The update of the comparison x configuration and the comparison x value is triggered periodi-
cally after the comparison x update period. It is defined by the field CUPR in the PWM_CMPMx.
The comparison unit has an update period counter independent from the period counter to trig-
ger this update. When the value of the comparison update period counter CUPRCNT (in
PWM_CMPMx) reaches the value defined by CUPR, the update is triggered. The comparison x
update period CUPR itself can be updated while the channel 0 is enabled by using the
PWM_CMPMUPDx register.
CAUTION: to be taken into account, the write of the register PWM_CMPVUPDx must be fol-
lowed by a write of the register PWM_CMPMUPDx.
The comparison match and the comparison update can be source of an interrupt, but only if it is
enabled and not masked. These interrupts can be enabled by the
and disabled by the
“PWM Interrupt Disable Register 2”
. The comparison match interrupt
and the comparison update interrupt are reset by reading the
“PWM Interrupt Status Register 2”
.
Summary of Contents for SAM4S Series
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