The following items are in reference to
.
• The
HALT
points represent where the channel halts operation when interrupted by a high priority channel 1
trigger, or when the HALT command is set, or when an emulation halt is issued and the FREE bit is cleared to
0.
• The ADDR registers are not affected by BEG_ADDR at the start of a transfer. BEG_ADDR only affects the
ADDR registers on a wrap or sync error. Following is what happens to each of the ADDR registers when a
transfer first starts:
– BEG_ADDR_SHADOW remains unchanged.
– ADDR_SHADOW remains unchanged.
– BEG_ADDR = BEG_ADDR_SHADOW
– ADDR = ADDR_SHADOW
• The active registers get updated when a wrap occurs. The shadow registers remain unchanged. Specifically:
– BEG_ADDR_SHADOW remains unchanged.
– ADDR_SHADOW remains unchanged.
– BE= WRAP_STEP
– ADDR = BEG_ADDR
• The active registers get updated when a sync error occurs. The shadow registers remain unchanged.
Specifically:
– BEG_ADDR_SHADOW remains unchanged.
– ADDR_SHADOW remains unchanged.
– BEG_ADDR remains unchanged.
– ADDR = BEG_ADDR
Probably the easiest way to remember all this is that:
• The shadow registers never change except by software.
• The active registers never change except by hardware, and a shadow register is only copied into its own
active register, never an active register by another name.
11.8 Overrun Detection Feature
The DMA contains overrun detection logic. When a peripheral event trigger is received by the DMA, the
PERINTFLG bit in the CONTROL register is set, pending the channel to the DMA state machine. When the burst
for that channel is started, the PERINTFLG is cleared. If however, between the time that the PERINTFLG bit is
set by an event trigger and cleared by the start of the burst, an additional event trigger arrives, the second trigger
will be lost. This condition will set the OVRFLG bit in the CONTROL register as in
. If the overrun
interrupt is enabled then the channel interrupt will be generated to the PIE module.
PIE
CONTROL.CHx
[PERINTFLG]
Latch
DMA
channel interrupt
CONTROL.CHx
[OVRFLG]
DMACHx interrupt generated
at beginning or end of transfer
MODE.CHx
[CHINTE]
PERx_INT
CONTROL.CHx
[ERRCLR]
MODE.CHx
[OVERNITE]
Figure 11-6. Overrun Detection Logic
Direct Memory Access (DMA) Module
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
739
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
Страница 2: ......