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CHAPTER 14 TOUCH PANEL INTERFACE UNIT (PIU)
User’s Manual U14272EJ3V0UM
299
14.7 Data Loss Conditions
The PIU issues a data lost interrupt request when any of the following four conditions exist.
1. Data for one coordinate has not been obtained within the interval period
2. The A/D port scan has not been completed within the time set via PIUSTBLREG register
3. Transfer of the next coordinate data starts while valid data for both pages remains in the buffer
4. The next data transfer starts while there is valid data in the ADPScan buffer
Once a data lost interrupt request occurs, the sequencer is forcibly changed to the Standby state.
The cause and response to each condition are as follows.
(1) When data for one coordinate has not been obtained within the interval period
Cause
This condition occurs when the AIU has exclusive use of the A/D converter and the PIU is therefore unable to
use the A/D converter.
If this data loss condition occurs frequently, implement a countermeasure that temporarily prohibits the AIU’s
use of the A/D converter.
Response
After clearing the data lost interrupt request by setting the PADDLOSTINTR bit to 1, set the PADATSTART bit
or PADSCANSTART bit of the PIUCNTREG register to restart the coordinate detection operation. Once the
data lost interrupt request is cleared, the page in which the loss occurred becomes invalid. If the valid data
prior to the data loss is needed, be sure to save the data that is being stored in the page buffer before
clearing the data lost interrupt request.
(2) When the A/D port scan has not been completed within the time set via PIUSTBLREG register
Cause
Same as cause of condition 1.
Response
After clearing the data lost interrupt request by setting the PADDLOSTINTR bit to 1, set the ADPSSTART bit
of the PIUASCNREG register to restart the A/D port scan operation. Once the data lost interrupt request is
cleared, the page in which the loss occurred becomes invalid. If the valid data prior to the data loss is
needed, be sure to save the data that is being stored in the page buffer before clearing the data lost interrupt
request.