AD1845 Analog Devices, AD1845 Datasheet - Page 15

• Manufacturer Part Number: AD1845
• Description: Parallel-port 16-Bit Soundport Stereo Codec
• Manufacturer: Analog Devices

REV. B
INT
PRDY
PL/R
PU/L
SOUR
CRDY
CL/R
CU/L
The PRDY, CRDY, and INT bits of this status register can change asynchronously to host accesses. The host may access this regis-
ter while the bits are transitioning. The host read may return a zero value just as these bits are changing, for example. A one value
would not be read until the next host access.
This register’s initial state after reset is “1100 1100.”
Status Register (ADR1:0 = 2)
ADR1:0
2
Playback Data Register Ready. The PIO Playback Data Register is ready for more data. This bit should only be
Interrupt Status. This sticky bit (the only one) indicates the status of the interrupt logic of the AD1845. This bit
is cleared by any host write of any value to this register. The IEN bit of the Pin Control Register determines
whether the state of this bit is reflected on the INT pin of the AD1845. The only interrupt conditions supported
by the AD1845 are generated by the underflow of the DMA Current Count Register or the Timer Registers.
0
1
used when direct programmed I/O data transfers are desired. This bit is read-only.
0
1
Playback Left/Right Sample. This bit indicates whether the PIO playback data needed is for the right channel
DAC or left channel DAC. This bit is read-only.
0
1
Playback Upper/Lower Byte. This bit indicates whether the PIO playback data needed is for the upper or lower
byte of the channel. This bit is read-only.
0
1
Sample Over/Underrun. This bit indicates that the most recent sample was not serviced in time and therefore
either a capture overrun (COR) or playback underrun (PUR) has occurred. The bit indicates an overrun for ADC
capture and an underrun for DAC playback. If both capture and playback are enabled, the source that set this bit
can be determined by reading COR and PUR. This bit changes on a sample by sample basis. This bit is read-only.
Capture Data Ready. The PIO Capture Data Register contains data ready for reading by the host. This bit
should only be used when direct programmed I/O data transfers are desired. This bit is read-only.
0
1
Capture Left/Right Sample. This bit indicates whether the PIO capture data waiting is for the right channel ADC
or left channel ADC. This bit is read-only.
0
1
Capture Upper/Lower Byte. This bit indicates whether the PIO capture data ready is for the upper or lower byte
of the channel. This bit is read-only.
0
1
Interrupt pin inactive
Interrupt pin active
DAC data is still valid. Do not overwrite.
DAC data is stale. Ready for next host data write value.
Right channel needed
Left channel or mono
Lower byte needed
Upper byte needed or any 8-bit mode
ADC data is stale. Do not reread the information.
ADC data is fresh. Ready for next host data read.
Right channel
Left channel or mono
Lower byte ready
Upper byte ready or any 8-bit mode
Data 7
CU/L
Data 6
CL/R
Data 5
CRDY
–15–
Data 4
SOUR
Data 3
PU/L
Data 2
PL/R
Data 1
PRDY
Data 0
AD1845
INT