CHAPTER 19 PIU (TOUCH PANEL INTERFACE UNIT)
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19.7 DATA LOSS INTERRUPT CONDITIONS
The PIU issues a PIUDataLostIntr interrupt when any of the following four conditions exist.
Once a PIUDataLostIntr interrupt occurs, the sequencer is forcibly changed to the Standby state.
1.
2.
3.
4.
Data for one coordinate has not been obtained within the interval period
The A/D port scan has not been completed within the time set via PIUSTBLREG
Transfer of the next coordinate data has begun while valid data for both pages remains in the buffer
The next data transfer starts while there is valid data in the ADPortScan buffer
(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 cause of the PIUDataLostIntr interrupt, set PIUCIUCNTREG’s PADATSTART bit or
PADSCANSTART bit to restart the coordinate detection operation. Once the PIUDataLostIntr interrupt 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
PIUDataLostIntr interrupt.
(2) When the A/D port scan has not been completed within the time set via PIUSTBLREG
Cause
Same as cause of condition 1
Response
After clearing the cause of the PIUDataLostIntr interrupt, set PIUASCNREG’s ADPSSTART bit to restart
the A/D port scan operation. Once the PIUDataLostIntr interrupt 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 PIUDataLostIntr interrupt.
(3) When transfer of the next coordinate data has begun while valid data for both pages remains in the
buffer
Cause
This condition is caused when the data buffer contains two pages of valid data (both the PIUPAGE1INTR
and PIUPAGE0INTR interrupts have occurred) but the valid data has not been processed. If the A/D
converter is used frequently, this may shorten the time that would normally be required from when both
pages become full until when the data loss occurs.