ADSP-2126x SHARC Processor Hardware Reference
9-29
Serial Ports
The 4-bit
MFD
field (bits 4-1) in the Multichannel Control registers
(
SPMCTL01
,
SPMCTL23
, and
SPMCTL45
) specifies a delay between the frame
sync pulse and the first data bit in multichannel mode. The value of
MFD
is
the number of serial clock cycles of the delay. Multichannel frame delay
allows the processor to work with different types of telephony interface
devices.
A value of zero for
MFD
causes the frame sync to be concurrent with the
first data bit. The maximum value allowed for
MFD
is 15. A new frame sync
may occur before data from the last frame has been received, because
blocks of data occur back to back.
Receive Multichannel Frame Sync Source
Bit 14 (IMFS) in the
SPCTL1
,
SPCTL3
and
SPCTL5
registers selects whether
the serial port uses an internally generated frame sync (if set, =1) or frame
sync from an external (if cleared, =0) source.
Active State Transmit Data Valid
Bit 16 (
LTDV
) in the
SPCTL0
,
SPCTL2
and
SPCTL4
registers selects the logic
level of the transmit data valid signals (
TDV01
,
TDV23
,
TDV45
) as active low
(inverted) if set (=1) or active high if cleared (=0). These signals are actu-
ally
SPORT0_FS
,
SPORT2_FS
and
SPORT4_FS
reconfigured as outputs during
multichannel operation. They indicate which timeslots have valid data to
transmit. Active high (0) is the default.
Multichannel Status Bits
Bit 29 (
ROVF
) in the
SPCTL1
,
SPCTL3
,
SPCTL5
registers provides status infor-
mation. This bit indicates if the channel has received new data if set (=1)
or not if cleared (=0) while the
RXSPxA
buffer is full. New data overwrites
existing data.
Bits 31-30 (
RXS_A)
in the
SPCTL1
,
SPCTL3
,
SPCTL5
registers indicate the sta-
tus of the channel’s receive buffer contents as follows: 00 = buffer empty,
01 = reserved, 10 = buffer partially full, 11 = buffer full.
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...