Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 983

Table A-84. SPCTLx Register Bit Descriptions (Standard Serial Mode)
(RW) (Cont'd)
Bit Name
25 SPTRAN
26 DERR_B
(RO)
28–27 DXS_B
(RO)
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Description
Data Direction Control. This bit controls the data direction of the
serial port channel A and B signals.
When cleared (= 0) the SPORT is configured to receive on both chan-
nels A and B. When configured to receive, the RXSPxA and RXSPxB
buffers are activated, while the receive shift registers are controlled by
SPORTx_CLK and SPORTx_FS. The TXSPxA and TXSPxB buffers
are inactive.
When set (= 1) the SPORT is configured to transmit on both channels
A and B. When configured to transmit, the TXSPxA and TXSPxB buf-
fers are activated, while the transmit shift registers are controlled by
SPORTx_CLK and SPORTx_FS. The RXSPxA and RXSPxB buffers
are inactive.
Channel B Error Status. When the SPORT is configured as a transmit-
ter, this bit provides transmit underflow status. If FSR = 1, DERR_x bit
indicates whether the SPORTx_FS signal (from an internal or external
source) occurred while the DXS_x buffer was empty. The SPORTs
transmit data whenever they detect a SPORTx_FS signal.
0 = No SPORTx_FS signal occurred while TXSPxA/B buffer is empty.
1 = SPORTx_FS signal occurred while TXSPxA/B buffer is empty.
If FSR = 0, DERR_x is set whenever the SPORT is required to transmit
and the transmit buffer is empty.
When the SPORT is configured as a receiver, this bit provides receive
overflow status. If FSR = 1, DERR_x bit indicates whether the
SPORTx_FS signal (from an internal or external source) occurred while
the DXS_x buffer was full. The SPORTs receive data whenever they
detect a SPORTx_FS signal. As a receiver, it indicates when the channel
has received new data while the receive buffer is full. New data over-
writes existing data.
0 = No SPORTx_FS signal occurred while RXSPxA/B buffer is full.
1 = SPORTx_FS signal occurred while RXSPxA/B buffer is full.
If FSR = 0, DERR_x is set whenever the SPORT is required to receive
and the receive buffer is full.
Channel B Data Buffer Status. Indicates the status of the serial port's
channel B data buffer (RXSPxB or TXSPxB) as follows:
00 = Empty
10 = Partially full
11 = Full
Registers Reference
A-157