Microtalk

CRC Algorithms

Frida Gail Rojas Contreras

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09:47

EOC 2022

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Frida Gail Rojas Contreras

Frida (a.k.a. Gail) was an embedded engineering supervisor for end-to-end product development teams in buildings automation industry. Recently, she has been focusing on being a full-time embedded systems developer in IoT networking industry. She loves learning about new technologies and particularly enjoys working with solutions that involve firmware and math. Frida holds a Bachelor's degree in Mechatronics Engineering from Insitiuto Tecnológico Autónomo de México (ITAM) and a Master's degree in Electrical Engineering for Control Theory field from Universidad Nacional Autónoma de México (UNAM).

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C High Reliability Software Software Design

Microtalk

CRC Algorithms

Frida Gail Rojas Contreras

09:47 EOC 2022

Frida Gail Rojas Contreras

09:47

Cyclic Redundancy Checks are a vastly used method for error detection and they are foundationally based on math. This short talk aims aims to give an overview of CRC concepts, their algorithms design and some of the ways that they can be implemented within a solution.

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In the talk, which component of the CRC binary-division process does the speaker say is the key factor that determines the CRC properties used to detect errors?

A The quotient produced by the binary division

B The divisor (the generator polynomial)

C The original message length alone

D The CRC bits appended before division

E A checksum formed by summing message bytes

Which statement best summarizes the practical trade-off between the loop-driven and table-driven CRC implementations described in the talk?

A Loop-driven implementations are faster, while table-driven ones are slower but use less memory.

B Loop-driven implementations perform bit-by-bit operations in a single routine and take more processing time; table-driven implementations use a precomputed lookup table stored in non-volatile memory and run faster.

C Table-driven implementations avoid any precomputation and therefore require no non-volatile memory.

D Loop-driven implementations require a pre-initialized crc_table stored in non-volatile memory to run efficiently.

E Table-driven implementations are slower but produce more accurate CRCs because they check bits multiple times.

Why does the speaker say CRCs are so widely used in industry communication protocols?

A Because CRCs can automatically correct errors without retransmission

B Because efficient generator polynomials that catch errors are standardized and those standards are adopted by industry protocols

C Because CRCs encrypt messages to prevent tampering

D Because CRC widths must always match data word sizes exactly, forcing their use

E Because CRCs compress data and reduce bandwidth usage

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RT

Score: 0 | 1 year ago | no reply

Ok, this presentation is short, so I get it, there is just so much information you can have in. Here are some questions.
How many bit errors can you detect?
Are any polynomials "better" than others at detecting errors?
Depending on the physical transmission layer, are some polynomials better suited for certain applications than others?

DS

Score: 0 | 3 years ago | no reply

Great explanation of CRCs! It clarified my undertanding of them.

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