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Code for PRBS / PN generation (preferable for AVR)

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Eugen_E

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generation of prbs

Hello,

I need a code or algorithm to generate PRBS on uC.
I know about using LFSR with feedback for maximal length, but that method seems to be less appropriate for an 8 bit microcontroller - involves lots of bit shifting and testing, it's hard to scale for sequences longer than 2^8 - 1 and this slows the output rate.
I would like something to use byte-oriented instructions rather than bit-oriented.

Thanks
 

prbs lfsr avr code

Using high level programming languages, e, g, C, you would use a long variable for shift register and a constant long XOR mask to generate feedback. That way you'll find the code in literature. Although operation isn't optimized to the limited, the function can be used conveniently without thinking about single bitshifts.

The C shift operation sr <<= 1 is coded by the uP simply as multiple 8-bit RLC operation (rotate left trough carry), which can be easily chained to any wanted bit length, additionally using a storage in memory for shift register, of course. Programming details depend on the respective uP's programming model. When coding in assembler, feedback bits could be evaluated for needed bits explicitely.

Regards,
Frank
 

prbs code

Any idea where I can get PRBS generator and analyzer code in verilog?
 

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