AT572D940HF_08 Datasheet, PDF (49/745 Pages) ATMEL Corporation – DIOPSIS 940HF ARM926EJ-S PLUS ONE GFLOPS DSP

AT572D940HF Preliminary
All temporary conditions on the AHB bus, like loosing grant or page fault or retry/split condition,
do not change the DMA channel that is currently operating (i.e. no new arbitration).
The DMA channels are serially processed and have fixed priority, the highest is channel number
3, the lowest is number 0.
Highest priority channel 3 is used by the PMU (if enabled), so the channel 3 parameters have to
be always considered scratched by a user application because they are modified by the PMU.
Several PMU DMA parameters (like chunck length, modifiers, external addresses) are set at
bootstrap and they must be kept fixed during the program execution.
Many parameters could be fixed throughout the entire application; moreover, thanks to the pos-
sibility to redo the transfer or to continue the transfer with the same parameters and the current
addresses, it could be also convenient to assign a DMA channel to a specific repetitive task,
saving most of the programming costs (i.e to access peripheral registers).
NOTE: Only 32-bit word accesses are supported.
49
7010A–DSP–07/08