Freescale Semiconductor MCF52277 Reference Manual page 495

Table 22-11. Touchscreen Controller Operating Modes (TSE = 1) (continued)
ASP_CR Field
Pen Sample FIFO
Data Format
AZX, X, AZY, Y,
01 1 1 1
No data is written
01 0 0 0
to the FIFO
01 0 0 1
No data is written
01 0 1 0
to the FIFO
01 0 1 1 AZX, X, AZY, Y
No data is written
10 1 X 0
to the FIFO
10 1 X 1
No data is written
10 0 X 0
to the FIFO
Freescale Semiconductor
After ASPE is set, the ADC starts the conversion of the AZX, X, AZY, and Y
coordinates sets. The result is written to pen sample FIFO. The measurement idle
time, as configured in ASP_TIM[MIDLECNT], is only inserted after the X
measurement. Between AZX and X and between AZY and Y, no measurement idle
time is inserted. After one round of measurement is complete, optional round idle
...
time may be inserted using ASP_TIM[RIDLECNT]. After that, the ASP automatically
starts another round of measurement. Between each round of conversion, there is an
option to insert one pen-down detection phase after the round idle phase using
ASP_CR[PENE]. Pen-up detection is active at this time as well.
The touchscreen is parked in the pen-detection state.
After ASPE is set, the ADC starts the conversion of the X, Y coordinates pairs. The
result is written to the pen sample FIFO. Between the X and Y conversion, optional
measurement idle time may be inserted using ASP_TIM[MIDLECNT]. After the X and
X,Y
Y conversions, no more conversions occur in the current round and pen-up detection
is active. To start another round of conversion, ASPE must be first cleared and set
again.
The touchscreen is parked in the pen-detection state.
After ASPE is set, the ADC starts the conversion of the AZX, X, AZY, and Y
coordinates sets. The result is written to pen sample FIFO. Between the conversion
of AZX to X and AZY to Y, no measurement idle time is inserted. The measurement
idle is only inserted after X measurement. After the X and Y conversions, no more
conversions occur in the current round and pen-up detection is active. To start
another round of conversion, ASPE must be first cleared and set again.
Auxiliary Input Sample Mode
The touchscreen is parked in the pen-detection state.
After ASPE is set, the continuous conversion of the active auxiliary channel begins.
U indicates the active auxiliary channel numbering from high to low. For example, if
i
the touchscreen controller is configured as a 4-wire interface, then ADC_IN[7:4] are
available for ADC conversion, by setting the corresponding bit in ASP_CR[APTN].
U ,...,U , Between each conversion except the round that wraps to the highest numbered
n 1
U ,...,U , auxiliary channel, optional measurement idle time can be inserted using
n 1
... ASP_TIM[MIDLECNT]. At the end of each round of conversion, there is an option to
insert round idle time using ASP_TIM[RIDLECNT]. Between each round of
conversion, you may insert one pen-down detection phase after the round idle phase.
The pen detection circuit is active if ASP_SET[SW] is set. AZE has no effect when
only general-purpose channels are converted.
The touchscreen is parked in the pen-detection state.
MCF52277 Reference Manual, Rev. 1
Touchscreen Controller/Analog-to-Digital Converter
Notes
22-15