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Hardware Description
3-38
Copyright © ARM Limited 2000. All rights reserved.
3.11 Touch screen controller
The CPU board has two touch screen controllers:
•
Burr-Brown ADS7843 touch screen controller, described in this section
•
Philips UCB1200 codec and touch screen controller on page 3-39.
The default option in systems with a factory-fitted touch screen is the ADS7843. To use
this controller, the touch screen is connected to the CPU board using the connector
JP15.
The ADS7843 touch screen controller provides a direct interface to a 4-wire resistive
touch screen. The ADS7843 operates from the 3V supply with a typical power
consumption of 750µW.
Figure 3-13 shows the architecture of the touch screen interface.
Figure 3-13 Touch screen interface (ADS7843)
The SA-1100 communicates with the ADS7843 using the SPI bus. The signal
PLD_SPI_CS3
is used to select the device. The maximum operating frequency for SPI
bus accesses to the ADS7843 is 115 kHz. The SPI clock for this device idles HIGH and
is sampled on the rising edge.
The ADS7843 issues interrupt requests by asserting
TCH_nPENIRQ
to the system
interrupt controller PLD (see Interrupt control on page 3-12), which forwards it onto
the CPU by asserting
CPU_GPIO[1]
and setting the PENIRQ bit in the interrupt flag
register.
Information about programming the device and timing for the SPI bus are provided in
Programming the touch screen controller on page 4-34.
CPU_SPI_SCLK
CPU_SPI_RXD
CPU_SPI_TXD
CPU_SPI_CS[2:0]
CPU_GPIO[1]
PLD_SPI_nEN
PLD_SPI_nCS3
TCH_nPENIRQ
SA-1100
System
controller
PLD
3-to-8
decoder
ADS7843
&
JP15
Touch screen
Содержание Prospector P1100
Страница 1: ...ARM DUI 0122A Prospector P1100 User Guide ...
Страница 4: ...iv Copyright ARM Limited 2000 All rights reserved ARM DUI 0122A ...
Страница 86: ...Hardware Description 3 54 Copyright ARM Limited 2000 All rights reserved ARM DUI 0122A ...
Страница 140: ...Connector reference A 18 Copyright ARM Limited 2000 All rights reserved ARM DUI 0122A ...