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Programming Examples
5-114
ADSP-BF537 Blackfin Processor Hardware Reference
Software-Triggered Descriptor Fetch Example
demonstrates a large list of descriptors that provide flow stop
mode configuration. Consequently, the DMA stops by itself as soon as the
work unit has finished. Software triggers the next work unit by simply
writing the proper value into the DMA configuration registers. Since these
values instruct the DMA controller to fetch descriptors in large list mode,
after being started the DMA immediately fetches the descriptor and, thus,
overwrites the configuration value again with the new settings.
Note the requirement that source and destination channels stop after the
same number of transfers. In between stops the two channels can have
completely individual structure.
Listing 5-7. Software-Triggered Descriptor Fetch
#define N 4
.section L1_data_a;
.byte2 arrSource1[N] = { 0x1001, 0x1002, 0x1003, 0x1004 };
.byte2 arrSource2[N] = { 0x2001, 0x2002, 0x2003, 0x2004 };
.byte2 arrSource3[N] = { 0x3001, 0x3002, 0x3003, 0x3004 };
.byte2 arrDest1[N];
.byte2 arrDest2[2*N];
.struct dma_desc_list descSource1 = {
descSource2, arrSource1,
WDSIZE_16 | DMAEN,
length(arrSource1), 2,
0, 0 /* unused values */
};
.struct dma_desc_list descSource2 = {
descSource3, arrSource2,
FLOW_LARGE | NDSIZE_7 | WDSIZE_16 | DMAEN,
length(arrSource2), 2,
0, 0 /* unused values */
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...