AD1821 Analog Devices, AD1821 Datasheet - Page 25
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AD1821
Manufacturer Part Number
AD1821
Description
Manufacturer
Analog Devices
Datasheet
1.AD1821.pdf
(44 pages)
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[Base+6]
PIO Playback/
Capture [7:0]
Note: All writes to the FIFO “MUST” contain 4 bytes of data.
[Base+7]
[Base+8]
PEN
PIO
PST
PC/L
PFMT [1:0] (RW)
DAZ
TRD
After setting format bits, sample data into the AD1821 must be ordered according to Figure 15, Table VI.
REV. 0
Reserved
Playback Configuration
(RW)
(RW)
(RW)
(RW)
(RW)
(RW)
PIO Data
TRD
7
7
7
The Programmed I/O (PIO) Data Registers for capture and playback are mapped to the same address. Writes
send data to the Playback Register and reads will receive data from the Capture Register.
Reading this register will increment the capture byte state machine so that the following read will be from the
next appropriate byte in the sample. The exact byte may be determined by reading the PIO Status Register.
Once all relevant bytes have been read, the state machine will stay pointed to the last byte of the sample
until a new sample is received.
Writing data to this register will increment the playback byte tracking state machine so that the following
write will be to the correct byte of the sample. Once all bytes have been written, subsequent byte writes will be
ignored. The state machine is reset when the current sample is transferred.
* 1 sample of 16-bit stereo
* 2 samples of 16-bit mono
* 2 samples of 8-bit stereo (Linear PCM, -law PCM, A-Law PCM)
* 4 samples of 8-bit mono (Linear PCM, -law PCM, A-Law PCM)
Playback Enable. This bit enables or disables programmed I/O data playback.
0
1
Programmed Input/Output. This bit determines whether the playback data is transferred via DMA or PIO.
0
1
Playback Stereo/Mono select. These bits select stereo or mono formatting for the input audio data
streams. In stereo, the Codec alternates samples between channels to provide left and right channel in-
put. For mono, the Codec captures samples on the left channel stereo.
0
1
Playback Companded/Linear Select. This bit selects between a linear digital representation of the audio signal
or a nonlinear companded format for all output data. The type of linear PCM or the type of companded for-
mat is defined by PFMT [1:0].
0
1
Playback Format. Use these bits to select the playback data format for output data according to Table VI and
Figure 15.
DAC zero. This bit forces the DAC to zero.
0
1
Transfer Request Disable. This bit enables or disables Codec DMA transfers during a Codec interrupt (indi-
cated by the SS Codec Status register’s INT bit being set [1]). This assumes Codec DMA transfers were en-
abled and the PEN or CEN bits are set.
0
1
DAZ
6
6
6
Disable
Enable
DMA transfers only
PIO transfers only
Mono
Stereo
Linear PCM
Companded
Repeat last sample
Force DAC to ZERO
Transfer Request Enable
Transfer Request Disable
PIO Playback/Capture [7:0]
5
5
5
PFMT [1:0]
Reserved [7:0]
4
4
4
PC/L
3
3
3
–25–
PST
2
2
2
PIO
1
1
1
PEN
0
0
0
RESET = [0xXX]
RESET = [0x00]
RESET = [0x00]
AD1821