CHAPTER 23:Stereo Audio DAC
S6J3200 Series Hardware Manual Document Number: 002-04852 Rev. *G
881
3.2.
Using DMA Transfers to Update DADR Register
DMA mode must be enabled by setting the DACTRL_DMAEN=1.
The Stereo Audio DAC module will then assert the DAC_DMA_REQ output when the number of free
entries in the FIFO buffer exceeds the value given by FEST. DAC_DMA_REQ stays active until the DMA
acknowledges the request by asserting DAC_DMA_ACK.
There is an internal down counter for this purpose which is reloaded with the value of FEST+1 when
DAC_DMA_REQ is asserted. It is decremented with each word written to the FIFO buffer. When the
counter reaches zero the transfer is complete and another DMA transfer may be requested. It is an error if
the DMA writes data to the FIFO while the down counter is zero.
Note:
−
The block size configured in the DMA must match DACT1
3.3.
Output Data Values of the Analog DAC
The data output pins of the analog DAC will be set to 0V when disabled.
When enabled, with a voltage reference at 0.5×AVCC(DAC), these pins will generate an output voltage
with peak-to-peak values of 0.609×AVCC(DAC). The table below shows the theoretical output voltage
values under typical conditions.
Table 2
DADR[31:16] or
DADR[15:0]
MSB LSB
DAC Left (or Right) data output pin voltage
0000H
(0.5 + 0.3365 × (0/32768)) × AVCC(DAC)
0001H
(0.5 + 0.3365 × (1/32768)) × AVCC(DAC)
0002H
(0.5 + 0.3365 × (2/32768)) × AVCC(DAC)
....
7FFEH
(0.5 + 0.3365 × (32766/32768)) × AVCC(DAC)
7FFFH
(0.5 + 0.3365 × (32767/32768)) × AVCC(DAC)
8000H
(0.5 + 0.3365 × (-32768/32768)) × AVCC(DAC)
8001H
(0.5 + 0.3365 × (-32767/32768)) × AVCC(DAC)
....
FFFDH
(0.5 + 0.3365 × (-3/32768)) × AVCC(DAC)
FFFEH
(0.5 + 0.3365 × (-2/32768)) × AVCC(DAC)
FFFFH
(0.5 + 0.3365 × (-1/32768)) × AVCC(DAC)
Note:
−
The Stereo Audio DAC does not feature integrated output voltage buffers.
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