National CP3BT26 manual Cvsd Status Register Cvstat

CP3BT26

DMAPI	The DMA Enable for PCM In bit enables hard-
	ware DMA control for writing PCM data into
	the PCMIN register. If cleared, DMA support
	is disabled. After reset, this bit is clear.
	0 – PCM input DMA disabled.
	1 – PCM input DMA enabled.
CVSDCONV	The CVSD to PCM Conversion Format field
	specifies the PCM format for CVSD/PCM con-
	versions. After reset, this field is clear.
	00	– CVSD <-> 8-bit µ-Law PCM.
	01	– CVSD <-> 8-bit A-Law PCM.
	10	– CVSD <-> Linear PCM.
	11	– Reserved.
PCMCONV	The PCM to PCM Conversion Format bit se-
	lects the PCM format for PCM/PCM conver-
	sions.
	0 – Linear PCM <-> 8-bit µ-Law PCM
	1 – Linear PCM <-> 8-bit A-Law PCM
RESOLUTION	The Linear PCM Resolution field specifies the
	attenuation of the PCM data for the linear
	PCM to CVSD conversions by right shifting
	and sign extending the data. This affects the
	log PCM data as well as the linear PCM data.
	The log data is converted to either left-justified
	zero-stuffed 13-bit (A-law) or 14-bit (u-law).
	The RESOLUTION field can be used to com-
	pensate for any change in average levels re-
	sulting from this conversion. After reset, these
	two bits are clear.
	00	– No shift.
	01	– 1-bit attentuation.
	10	– 2-bit attentuation.
	11	– 3-bit attentuation.

21.9.10 CVSD Status Register (CVSTAT)

The CVSTAT register is a 16-bit wide, read-only register that holds the status information of the CVSD/PCM module. At reset, and if the CVCTL1.CVEN bit is clear, all implemented bits are cleared.

7	5	4	3	2	1			0
CVINST		CVF	CVE	PCMINT		CVNF	CVNE
15			11	10				8
	Reserved				CVOUTST
CVNE	The CVSD In FIFO Nearly Empty bit indicates
	when only three CVSD data words are left in
	the CVSD In FIFO, so new CVSD data should

be written into the CVSD In FIFO. If the CVS- DINT bit is set, an interrupt will be asserted when the CVNE bit is set. If the DMACI bit is set, a DMA request will be asserted when this bit is set. The CVNE bit is cleared when the CVSTAT register is read.

0 – CVSD In FIFO is not nearly empty.

1 – CVSD In FIFO is nearly empty.

CVNF	The CVSD Out FIFO Nearly Full bit indicates
	when only three empty word locations are left
	in the CVSD Out FIFO, so the CVSD Out
	FIFO should be read. If the CVSDINT bit is
	set, an interrupt will be asserted when the
	CVNF bit is set. If the DMACO bit is set, a
	DMA request will be asserted when this bit is
	set. Software must not rely on the CVNF bit as
	an indicator of the number of valid words in
	the FIFO. Software must check the CVOUTST
	field to read the number of valid words in the
	FIFO. The CVNF bit is cleared when the
	CVSTAT register is read.
	0 – CVSD Out FIFO is not nearly full.
	1 – CVSD Out FIFO is nearly full.
PCMINT	The PCM Interrupt bit set indicates that the
	PCMOUT register is full and needs to be read
	or the PCMIN register is empty and needs to
	be loaded with new PCM data. The PCMINT
	bit is cleared when the CVSTAT register is
	read, unless the device is in FREEZE mode.
	0 – PCM does not require service.
	1 – PCM requires loading or unloading.
CVE	The CVSD In FIFO Empty bit indicates when
	the CVSD In FIFO has been read by the
	CVSD converter while the FIFO was already
	empty. If the CVSDERRORINT bit is set, an
	interrupt will be asserted when the CVE bit is
	set. The CVE bit is cleared when the CVSTAT
	register is read, unless the device is in
	FREEZE mode.
	0 – CVSD In FIFO has not been read while
	empty.
	1 – CVSD In FIFO has been read while emp-
	ty.
CVF	The CVSD Out FIFO Full bit set indicates
	whether the CVSD Out FIFO has been written
	by the CVSD converter while the FIFO was al-
	ready full. If the CVSDERRORINT bit is set,
	an interrupt will be asserted when the CVF bit
	is set. The CVF bit is cleared when the
	CVSTAT register is read, unless the device is
	in FREEZE mode.
	0 – CVSD Out FIFO has not been written
	while full.
	1 – CVSD Out FIFO has been written while
	full.
CVINST	The CVSD In FIFO Status field reports the
	current number of empty 16-bit word locations
	in the CVSD In FIFO. When the FIFO is emp-
	ty, the CVINST field will read as 111b. When
	the FIFO holds 7 or 8 words of data, the
	CVINST field will read as 000b.
CVOUTST	CVSD Out FIFO Status field reports the cur-
	rent number of valid 16-bit CVSD data words
	in the CVSD Out FIFO. When the FIFO is
	empty, the CVOUTST field will read as 000b.
	When the FIFO holds 7 or 8 words of data, the
	CVOUTST field will read as 111b.

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