Datasheet

629
6120F–ATARM–03-Oct-06
AT91SAM7X512/256/128 Preliminary
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
41.3.2.3 PIO: Drive Low NRST, PA0-PA30 and PB0-PB26
When NRST or PA0 - PA30 or PB0 - PB26 are set as digital inputs with pull-up enabled, driving
the I/O with an output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
41.3.3 Pulse Width Modulation Controller (PWM)
41.3.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty
Cycle Register is directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
41.3.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
41.3.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter
starts at 1.
Problem Fix/Workaround
None.
41.3.3.4 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled
by writing in the PWM_DIS Register just after enabling it (before completion of a Clock Period of
the clock selected for the channel), the PWM line is internally disabled but the CHIDx status bit
in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
41.3.4 Real Time Timer (RTT)
41.3.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the
RTT_SR is read, the corresponding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.