rtd BDM-610000075, Руководство пользователя

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68 CMX32M cpuModule BDM-610000075 Rev B
The scatter-gather DMA method allows continuous sampling at the maximum sample rate with the least
amount of operating system intervention. Because each channel has its own scatter-gather table, the data for
each channel is located in a separate area in system memory. Therefore the application software doesn’t need to
de-interlace the data.
The following steps are needed to use DMA operation:
1. Open the board as described in Board Open on page 77.
2. Allocate needed DMA buffers
3. Program Scatter-Gather table
4. Write channel and input configuration in CGT Register if needed (default is +/-10V, single ended)
5. Start conversion
6. Wait for DMA interrupt
7. Update Scatter-Gather table if needed
8. Process or move data if needed
9. Repeat to Step 6
Registers
Register Map
Table 51 aAIO Register Map
Name I/O Port 31-24 23-16 15-8 7-0
Control 0x09E0 CH_IRQ_ENA CH_IRQ_STAT MODE_RESET SELECT[3:0]
Pacer Clock Divider 0x09E4 PACER_DIVIDER
Advanced Setup 0x09E8 Reserved CUR_SGT_ROW CUR_BUFFER_OFFSET
Indexed registers controlled by 0x09E0[2:0]
Channel Control 0x09EC FILTER_CON SGT_ROW CH_MODE NEXT_
CHANNEL
A/D Result 0x09F0 AD_RESULT
Interrupt 0x09F4 IRQ_ENA IRQ_STAT
Threshold 0x09F8 THRESH_HIGH THRESH_LOW
DMA Buffer 0x09FC SGT_DATA