ARM Prospector P1100, User Manual, Page: 63 / 154

Hardware Description
ARM DUI 0122A Copyright © ARM Limited 2000. All rights reserved. 3-31
The SPI chip select lines are assigned as shown in Table 3-15 on page 3-31. One chip
select signal,
PLD_SPI_nCS7
, is reserved as a null select (do not use this signal for
expansion). This is used to deselect devices on the SPI bus because they require their
nCS
line to be deasserted as part of the transfer protocol.
3.8.4 SPI bus timing
The different devices attached to the SPI bus have different timing requirements.
• The UR8HC007-001 SPI interface timing requirements are described in
Keyboard controller host interface timing on page 4-23.
• The MMC interface timing requirements are described in MMC transaction
timing on page 4-33.
• The touch screen controller timing requirements are described in Programming
the touch screen controller on page 4-34.
Table 3-15 SPI chip select assignment
CPU_SPI_CS[2:0] Active chip select Device
000 PLD_SPI_nCS0 Keyboard controller
001 PLD_SPI_nCS1 MMC Socket 1
010 PLD_SPI_nCS2 MMC Socket 2
011 PLD_SPI_nCS3 Touch screen controller
100 PLD_SPI_nCS4 System expansion
101 PLD_SPI_nCS5 System expansion
110 PLD_SPI_nCS6 System expansion
111 PLD_SPI_nCS7 Null chip select. This is asserted when
no devices are required. Do not use this
chip select for system expansion.