Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 518

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Programming Model

In the ADSP-214xx processors the

allows SPORT initialization regardless of the state of the external

frame sync. The SPORT starts the transfer on the next valid edge.

Companding As a Function

Since the values in the transmit and receive buffers are actually com-

panded in place, the companding hardware can be used without

transmitting (or receiving) any data, for example during testing or debug-

ging. This operation requires one peripheral clock cycle of overhead, as

described below. For companding to execute properly, program the

SPORT registers prior to loading data values into the SPORT buffers.

To compress data in place without transmitting use the following

bits should be = 0.

2. Enable companding in the

trol register.

3. Write a 32-bit data word to the transmit buffer. Companding is

calculated in this cycle.

4. Wait two cycles. Any instruction not accessing the transmit buffer

can be used to cause this delay. This allows the serial port com-

panding hardware to reload the transmit buffer with the

companded value.

5. Read the 8-bit compressed value from the transmit buffer.

To expand data in place, use the same sequence of operations with the

receive buffer instead of the transmit buffer. When expanding data in this

way, set the appropriate serial word length (

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bit to 1 in the

ADSP-214xx SHARC Processor Hardware Reference

field of the

transmit con-

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