VR4102 datasheet(405/701 Pages) NEC

405 / 701 page

CHAPTER 19 PIU (TOUCH PANEL INTERFACE UNIT)

405

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.

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.

VR4102 Datasheet(PDF) 405 Page - NEC