35
32142DS–06/2013
ATUC64/128/256L3/4U
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.
6.2.6 TC
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.
6.2.7 CAT
1. CAT QMatrix sense capacitors discharged prematurely
At the end of a QMatrix burst charging sequence that uses different burst count values for
different Y lines, the Y lines may be incorrectly grounded for up to n-1 periods of the periph-
eral bus clock, where n is the ratio of the PB clock frequency to the GCLK_CAT frequency.
This results in premature loss of charge from the sense capacitors and thus increased vari-
ability of the acquired count values.
Fix/Workaround
Enable the 1kOhm drive resistors on all implemented QMatrix Y lines (CSA 1, 3, 5, 7, 9, 11,
13, and/or 15) by writing ones to the corresponding odd bits of the CSARES register.
2. Autonomous CAT acquisition must be longer than AST source clock period
When using the AST to trigger CAT autonomous touch acquisition in sleep modes where the
CAT bus clock is turned off, the CAT will start several acquisitions if the period of the AST
source clock is larger than one CAT acquisition. One AST clock period after the AST trigger,
the CAT clock will automatically stop and the CAT acquisition can be stopped prematurely,
ruining the result.
Fix/Workaround
Always ensure that the ATCFG1.max field is set so that the duration of the autonomous
touch acquisition is greater than one clock period of the AST source clock.
3. CAT consumes unnecessary power when disabled or when autonomous touch not
used
A CAT prescaler controlled by the ATCFG0.DIV field will be active even when the CAT mod-
ule is disabled or when the autonomous touch feature is not used, thereby causing
unnecessary power consumption.
Fix/Workaround
If the CAT module is not used, disable the CLK_CAT clock in the PM module. If the CAT
module is used but the autonomous touch feature is not used, the power consumption of the
CAT module may be reduced by writing 0xFFFF to the ATCFG0.DIV field.
6.2.8 aWire
1. aWire MEMORY_SPEED_REQUEST command does not return correct CV
The aWire MEMORY_SPEED_REQUEST command does not return a CV corresponding to
the formula in the aWire Debug Interface chapter.
Fix/Workaround
