819
32099I–01/2012
AT32UC3L016/32/64
35.2.11
ADCIFB
1.
Using STARTUPTIME larger than 0x1F will freeze the ADC
Writing a value larger than 0x1F to the Startup Time field in the ADC Configuration Register
(ACR.STARTUP) will freeze the ADC, and the Busy Status bit in the Status Register
(SR.BUSY) will never be cleared.
Fix/Workaround
Do not write values larger than 0x1F to ACR.STARTUP.
35.2.12
CAT
1.
CAT asynchronous wake will be delayed by one AST event period
If the CAT detects a condition the should asynchronously wake the device in static mode,
the asynchronous wake will not occur until the next AST event. For example, if the AST is
generating events to the CAT every 50ms, and the CAT detects a touch at t=9200ms, the
asynchronous wake will occur at t=9250ms.
Fix/Workaround
None.
2.
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.
3.
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.
4.
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.
35.2.13
aWire
1.
aWire CPU clock speed robustness
The aWire memory speed request command counter warps at clock speeds below approxi-
mately 5kHz.
Fix/Workaround