Datasheet

744
32133D–11/2011
UC3D
35.3.3 Timer Counter
1. Channel chaining skips first pulse for upper channel
When chaining two channels using the Block Mode Register, the first pulse of the clock
between the channels is skipped.
Fix/Workaround
Configure the lower channel with RA = 0x1 and RC = 0x2 to produce a dummy clock cycle
for the upper channel. After the dummy cycle has been generated, indicated by the
SR.CPCS bit, reconfigure the RA and RC registers for the lower channel with the real
values.
35.3.4 TWIS
1. TWIS stretch on Address match error
When the TWIS stretches TWCK due to a slave address match, it also holds TWD low for
the same duration if it is to be receiving data. When TWIS releases TWCK, it releases TWD
at the same time. This can cause a TWI timing violation.
Fix/Workaround
None.
2. Clearing the NAK bit before the BTF bit is set locks up the TWI bus
When the TWIS is in transmit mode, clearing the NAK Received (NAK) bit of the Status Reg-
ister (SR) before the end of the Acknowledge/Not Acknowledge cycle will cause the TWIS to
attempt to continue transmitting data, thus locking up the bus.
Fix/Workaround
Clear SR.NAK only after the Byte Transfer Finished (BTF) bit of the same register has been
set.
3. CAT
4. CAT module does not terminate QTouch burst on detect
The CAT module does not terminate a QTouch burst when the detection voltage is
reached on the sense capacitor. This can cause the sense capacitor to be charged more
than necessary. Depending on the dielectric absorption characteristics of the capacitor, this
can lead to unstable measurements.
Fix/Workaround
Use the minimum possible value for the MAX field in the ATCFG1, TG0CFG1, and
TG1CFG1 registers.
35.3.5 PWMA
1. The SR.READY bit cannot be cleared by writing to SCR.READY
The Ready bit in the Status Register will not be cleared when writing a one to the corre-
sponding bit in the Status Clear register. The Ready bit will be cleared when the Busy bit is
set.
Fix/Workaround
Disable the Ready interrupt in the interrupt handler when receiving the interrupt. When an
operation that triggers the Busy/Ready bit is started, wait until the ready bit is low in the Sta-
tus Register before enabling the interrupt.
2.