IDT Device Controller
Device Control Registers
79RC32438 User Reference Manual
6 - 8
November 4, 2002
Notes
Device [0..5] Timing Control Register
Figure 6.5 Device [0..5] Timing Control Register (DEV[0..5]TC)
BWE
Description:
Burst Write Enable.
When this bit is set, the device controller performs burst device write trans-
actions whenever possible. When this bit is cleared, burst device write transactions are never
generated to the device.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value
WAM
Description:
Wait/Ack Mode.
This bit controls the operation of the WAITACKN signal. When this bit is a one,
the WAITACKN signal operates as a Motorola style active low transfer acknowledge signal.
When this bit is a zero, the WAITACKN signal operates as an Intel style active low wait signal.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value
PRD
Description:
Postread Delay.
This field contains the delay, in clock cycles, from when the RC32438 clocks in
data from the data bus during a device read transaction until the start of a new transaction. Pro-
gramming this value to zero results in a postread delay of one clock cycle.
If PRD or PWD is equal or less than CSH, chip select may remain asserted between transactions
to the same device (i.e., back-to-back transactions).
Initial Value:
0xF
Read Value:
Previous value written
Write Effect:
Modify value
PWD
Description:
Postwrite Delay.
This field contains the delay, in clock cycles, from when the RC32438 negates
the byte write enable signals during a device write transaction until the start of a new transaction.
Programming this value to zero results in a postread delay of one clock cycle.
If PRD or PWD is equal or less than CSH, chip select may remain asserted between transactions
to the same device (i.e., back-to-back transactions).
If PWD is equal or less than WDH and BWD is zero, the byte write enable signals may remain
asserted between write transactions to the same device (i.e., back-to-back write transactions).
Initial Value:
0xF
Read Value:
Previous value written
Write Effect:
Modify value
DEV[0..5]TC
0
31
19
0
4
PRD
4
PWD
3
WDH
2
CSH