Registers
1563
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Parallel Port (uPP)
32.3.7 uPP Threshold Configuration Register (UPTCR)
The uPP threshold configuration register (UPTCR) controls the transmit threshold for each interface
channel and the read threshold for each DMA channel. Using larger thresholds can decrease internal bus
traffic and increase performance, especially when the uPP is operating in a loaded system. The UPTCR is
shown in
and described in
.
Figure 32-22. uPP Threshold Configuration Register (UPTCR)
31
26
25
24
23
18
17
16
Reserved
TXSIZEB
Reserved
TXSIZEA
R-0
R/W-0
R-0
R/W-0
15
10
9
8
7
2
1
0
Reserved
RDSIZEQ
Reserved
RDSIZEI
R-0
R/W-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 32-17. uPP Threshold Configuration Register (UPTCR) Field Descriptions
Bit
Field
Value
Description
31-26
Reserved
0
Reserved
25-24
TXSIZEB
0-3h
Transmit threshold for Channel B. Controls the number of bytes that interface Channel B waits before
beginning transmission. Only applies when Channel B is configured in transmit mode using the MODE
bit in the uPP channel control register (UPCTL).
0
64 bytes
1
128 bytes (requires DMA descriptor byte count greater than 64)
2h
Reserved
3h
256 bytes (requires DMA descriptor byte count greater than 192)
23-18
Reserved
0
Reserved
17-16
TXSIZEA
0-3h
Transmit threshold for Channel A. Controls the number of bytes that interface Channel A waits before
beginning transmission. Only applies when Channel A is configured in transmit mode using the MODE
bit in the uPP channel control register (UPCTL).
0
64 bytes
1
128 bytes (requires DMA descriptor byte count greater than 64)
2h
Reserved
3h
256 bytes (requires DMA descriptor byte count greater than 192)
15-10
Reserved
0
Reserved
9-8
RDSIZEQ
0-3h
Read threshold for DMA Channel Q. Controls burst size for DMA Channel Q.
0
64 bytes
1
128 bytes
2h
Reserved
3h
256 bytes
7-2
Reserved
0
Reserved
1-0
RDSIZEI
0-3h
Read threshold for DMA Channel I. Controls burst size for DMA Channel I.
0
64 bytes
1
128 bytes
2h
Reserved
3h
256 bytes