Intel PXA255 manual Parallel Data Formats for Fifo Storage, National Microwire* Frame Format

Models: PXA255

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Synchronous Serial Port Controller

Figure 8-3shows the National Microwire frame format with 8-bit command words for single and back-to-back frame transmissions.

Figure 8-3. National Microwire* Frame Format

SSPSCLK

SSPSFRM

SSPTXD

SSPRXD

...

...

Bit<7> ... Bit<0>

8-Bit Control

...

...

...

...

1 Clk

Bit<N> ... Bit<0>

4 to 16 Bits

SSPSCLK

SSPSFRM

SSPTXD Bit<0>

SSPRXD

 

 

 

 

 

 

 

Single Transfer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

...

 

 

 

 

...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

...

 

 

 

 

...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

...

 

 

Bit<7>

...

Bit<0>

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 Clk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit<N>

...

Bit<0>

 

 

...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Continuous Transfers

 

 

 

...

...

...

1 Clk

Bit<N> ... Bit<0>

8.4.2Parallel Data Formats for FIFO Storage

Data in the FIFOs is stored with one 16-bit value per data sample with no regard to the format’s data word length. In each 16-bit field, the stored data sample is right-justified, the word’s least significant bit is stored in bit 0, and unused bits are packed as zeroes above the most significant bit. Logic in the SSPC automatically left-justifies data in the Transmit FIFO so the sample is properly transmitted on SSPTXD in the selected frame format.

8-6

Intel® PXA255 Processor Developer’s Manual

Page 316
Image 316
Intel PXA255 manual Parallel Data Formats for Fifo Storage, National Microwire* Frame Format