Register Descriptions
1257
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
External Peripheral Interface (EPI)
17.11.19 EPI Write FIFO Count (EPIWFIFOCNT) Register, offset 0x204
This register contains the number of slots currently available in the WFIFO. This register may be used for
polled writes to avoid stalling and for blocking reads to avoid excess stalling (due to undrained writes). An
example use for writes may be:
for (idx = 0; idx < cnt; idx++) {
while (EPIWFIFOCNT== 0) ;
*ext_ram = *+;
}
The above code ensures that writes to the address mapped location do not occur unless the WFIFO has
room. Although polling makes the code wait (spinning in the loop), it does not prevent interrupts being
serviced due to bus stalling.
Figure 17-46. EPI Write FIFO Count (EPIWFIFOCNT) Register [offset 0x204]
31
3
2
0
Reserved
WTAV
R-0x0000.000
R-0x4
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 17-32. EPI Write FIFO Count (EPIWFIFOCNT) Register Field Descriptions
Bit
Field
Value
Description
31-3
Reserved
Reserved
2-0
WTAV
Available Write Transactions
The number of write transactions available in the WFIFO. When clear, a write is stalled waiting for a
slot to become free (from a preceding write completing).