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SAM9G45 [DATASHEET]
6438K–ATARM–12-Feb-13
depending on the TSFREQ field in the register TSADCC_MR. In the interleaved mode at least one ADC channel
must be enabled.
In the Interleaved Mode, the channels 0 to 3 corresponding to the Touch Screen inputs are automatically activated
This mode allows periodic conversion of the remaining channels at high sampling rate and converted data trans-
ferred in memory with the PDC while the touch screen conversions are performed at low rate. The PDC transfers
The resolution can be configured for the channel 4 to 7 only, through the LOWRES bit. The resolution for the con-
version made on channels 0 to 3 is forced to 10 bits.
At each trigger, the sequence performed depends on a Trigger Counter, which is compared at the end to the Touch
Screen Frequency, as defined by the field TSFREQ in the register TSADCC_MR:
Touch Screen Frequency = Trigger Frequency / (2TSFREQ+1)
unless TSFREQ is programmed at 0 or 1. In such cases, the Touch Screen Frequency is one-sixth of the Trigger
Frequency.
As TSFREQ varies between 0 and 15, this results in the ADC channels being converted between 6 to 65536 less
often than the Touch Screen channels.
For Trigger Counter at 0:
1.
Close the switches on the inputs X
P and XM during the Sample and Hold Time.
2.
Convert Channel X
M and store the result in TSADCC_CDR1.
3.
If Channel 4 to Channel 7 are enabled, convert Channels and store result in the corresponding
TSADCC_CDRx and TSADCC_LCDR.
4.
Set Trigger Counter to 1.
For Trigger Counter at 1:
1.
Close the switches on the inputs X
P and XM during the Sample and Hold Time.
2.
Convert Channel X
P, subtract TSADCC_CDR1 from the result and store the subtraction result in
TSADCC_CDR0 (and also in TSADCC_LCDR if PDCEN is enabled).
3.
If Channel 4 to Channel 7 are enabled, convert Channels and store result in the corresponding
TSADCC_CDRx and TSADCC_LCDR.
4.
Set Trigger Counter to 2.
For Trigger Counter at 2:
1.
Close the switches on the inputs X
P and XM during the Sample and Hold Time.
2.
Convert Channel Y
P,, subtract TSADCC_CDR1 from the result and store the subtraction result in
TSADCC_CDR1 (and also in TSADCC_LCDR if PDCEN is enabled).
3.
If Channel 4 to Channel 7 are enabled, convert Channels and store result in the corresponding
TSADCC_CDRx and TSADCC_LCDR.
4.
Set Trigger Counter to 3.
For Trigger Counter at 3: