AD1846

REV. A

–13–

Status Register (ADR1:0 = 2)

ADR1:0

Data 7

Data 6

Data 5

Data 4

Data 3

Data 2

Data 1

Data 0

2

CU/L

CL/R

CRDY

SOUR

PU/L

PL/R

PRDY

INT

INT

Interrupt Status. This sticky bit (the only one) indicates the status of the interrupt logic of the AD1846. 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 AD1846. The only interrupt condition supported by the AD1846 is generated by the

underflow of the DMA Current Count Register.

0

Interrupt pin inactive

1

Interrupt pin active

PRDY

Playback Data Register Ready. The PIO Playback Data Register is ready for more data. This bit should only be used when

direct programmed I/O data transfers are desired. This bit is read only.

0

DAC data is still valid. Do not overwrite.

1

DAC data is stale. Ready for next host data write value.

PL/R

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

Right channel needed

1

Left channel or mono

PU/L

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

Lower byte needed

1

Upper byte needed or any 8-bit mode

SOUR

Sample Over/Underrun. This bit indicates that the most recent sample was not serviced in time and therefore either a cap-

ture 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 which 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.

CRDY

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

ADC data is stale. Do not reread the information.

1

ADC data is fresh. Ready for next host data read.

CL/R

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

Right channel

1

Left channel or mono

CU/L

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

Lower byte ready

1

Upper byte ready or any 8-bit mode

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 “1” value

would not be read until the next host access.

This registers’s initial state after reset is “1100 1100.”