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Registers
695
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Enhanced Direct Memory Access (EDMA3) Controller
17.4.3.5 Read Command Rate Register (RDRATE)
The EDMA3 transfer controller issues Read commands at a rate controlled by the Read command rate
register (RDRATE). The RDRATE defines the number of idle cycles that the Read controller must wait
before issuing subsequent commands. This applies both to commands within a transfer request packet
(TRP) and for commands that are issued for different transfer requests (TRs). For instance, if RDRATE is
set to 4 cycles between reads, there are 32 inactive cycles between reads.
RDRATE allows flexibility in transfer controller access requests to an endpoint. For an application,
RDRATE can be manipulated to slow down the access rate, so that the endpoint may service requests
from other masters during the inactive EDMA3TC cycles.
The RDRATE is shown in
and described in
.
NOTE:
It is expected that the RDRATE value for a transfer controller is static, as it is decided based
on the application requirement. It is not recommended to change this setting on the go.
Figure 17-90. Read Command Rate Register (RDRATE)
31
16
Reserved
R-0
15
3
2
0
Reserved
RDRATE
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 17-73. Read Command Rate Register (RDRATE) Field Descriptions
Bit
Field
Value
Description
31-3
Reserved
0
Reserved
2-0
RDRATE
0-7h
Read rate. Controls the number of cycles between Read commands. This is a global setting that applies
to all TRs for this EDMA3TC.
0
Reads issued as fast as possible.
1h
4 EDMA3TC cycles between reads.
2h
8 EDMA3TC cycles between reads.
3h
16 EDMA3TC cycles between reads.
4h
32 EDMA3TC cycles between reads.
5h-7h
Reserved