VR4102 datasheet(381/701 Pages) NEC

381 / 701 page

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CHAPTER 19 PIU (TOUCH PANEL INTERFACE UNIT)

This chapter describes the PIU’s operations and register settings.

19.1 GENERAL

The PIU uses an on-chip A/D converter and detects the X and Y coordinates of pen contact locations on the

touch panel and scans the general-purpose A/D input port.

Since the touch panel control circuit and the A/D

converter (conversion precision: 10 bits) are both on-chip, the touch panel is connected directly to the VR4102.

The PIU’s function, namely the detection of X and Y coordinates, is performed partly by hardware and partly by

software.

Hardware tasks : • Touch panel applied voltage control

• Reception of coordinate data

Software task

: • Processing of coordinate data based on data sampled by hardware

Features of the PIU’s hardware tasks are described below.

• Can be directly connected to touch panel with four-pin resistance layers (on-chip touch panel driver)

• Interface for on-chip A/D converter

• Voltage detection at three general-purpose AD ports and one audio input port

• Operation of A/D converter based on various settings and control of voltage applied to touch panel

• Sampling of X-coordinate and Y-coordinate data

• Variable coordinate data sampling interval

• Interrupt is triggered if pen touch occurs regardless of CPU operation mode (interrupts do not occur when in

CPU hibernate mode)

• Four dedicated buffers for up to two pages each of coordinate data

• Four buffers for A/D port scan

• Auto/manual options for coordinate data sampling start/stop control

VR4102 Datasheet(PDF) 381 Page - NEC