Hardware Description and Board Operation
3-24
M68VZ328ADS USER’S MANUAL
MOTOROLA
3.8.2 Touch Panel Interface
The VZADS board is equipped with Burr-Brown Touch Panel Controller ADS7843. Figure 3-
7 shows the interface of Touch Panel Controller. Totally one I/O signal, one interrupt capable
I/O signal and one set of SPIM signals from MC68VZ328 are used to implement the touch
panel circuitry. All of these signals can be shared for other devices when touch panel inter-
face controller is being disabled. The on-board touch panel controller can be disabled by
turning both DIP switches S1-5, S1-6 off.
The ADS7843 is a 12-bit sampling analog-to-digital converter (ADC) with a synchronous
serial interface and low on-resistance switches for driving touch screens. The ADS7843
communicates with MC68VZ328 through SPI (Serial Peripheral Interface). In this case,
ADS7843 is slave, and MC68VZ328 is master. For the details on the operation of ADS7843,
please refer to its datasheet. The datasheet is available on the web:
http://www.burr-brown.com
For more details on the operation of resistive touch panel, please refer to Appendix A .
Table 3-7. Signal Assignment for Touch Panel Controller
Signals
Function
SPMRXD, SPMTXD, SPMCLK
This set of serial port interface signals performs data transfer with
ADS7843. For detailed operation on the SPI port, please refer to the
MC68VZ328 User’s Manual.
~IRQ5
This signal is driven from an MC68VZ328 interrupt capable I/O pin.
PB6
The MC68VZ328 general I/O signal is used to select the ADS7843 on data
transfer.
ADS7843
CS
PENIRQ
IRQ5
PB6
SPMCLK
SPMTXD
SPMRXD
DCLK
DIN
DOUT
Touch Panel
TOP
RIGHT
LEFT
BOTTOM
MC68VZ328
S1-6
S1-5
VCC
Figure 3-7. Touch Panel Controller Interface
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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