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PCI CD/CDa Configurable DMA Interface User’s Guide Registers

EDT, Inc. May 2007 31

Direction Control Registers

Size 8-bit

I/O read-write

Address 0x06, 0x07

Access PCD_DIRA, PCD_DIRB

Comment PCI CD only — not used for PCI CDa

The direction control registers determine whether the physical drivers or receivers

on the PCI CD interface are inputs or outputs. The PCI CDa’s inputs are always

enabled. To enable outputs, use bit 1 (SELRXT) of the Interface Configuration

Each pin on the PCI CD can be programmed as either an input or an output. Pins are normally

configured for inputs or outputs as documented in the connector pinout shown on page Table 3 on

page 17. The PCI CD driver modifies the data bits appropriately for a read() or write() system call.

Setting the same pins to serve as both input and output is useful for testing. Setting pins to serve as

neither input nor output is not useful.

Direction Control Register A controls the data direction. Direction Control Register B controls the

direction of the control bit.

For example, to implement the interface documented in Table 3 for a write() operation, set the A

0xCC.

Table 6. Direction Control Register A and B

B 15 Pins 22 and 62 are outputs when this bit is low.

14 Pins 19, 59, 21, and 61 are outputs when this bit is low.

13 Pins 32–39 are outputs when this bit is low.

12 Pins 72–79 are outputs when this bit is low.

11 Pins 24–31 are outputs when this bit is low.

10 Pins 64–71 are outputs when this bit is low.

9 Pins 24–31 are inputs when this bit is low.

8 Pins 64–71 are inputs when this bit is low.

A 7 Pins 11–18 are outputs when this bit is low.

6 Pins 51–58 are outputs when this bit is low.

5 Pins 3–10 are outputs when this bit is low.

4 Pins 43–50 are outputs when this bit is low.

3 Pins 11–18 are inputs when this bit is low.

2 Pins 51–58 are inputs when this bit is low.

1 Pins 3–10 are inputs when this bit is low.

0 Pins 43–50 are inputs when this bit is low.

1 2 ... 30 31 32 33 34 35 36 37 38 39 40

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CDA CD 60 Guide de l'utilisateur Page 35