[Q] How to do a CRC8

[Sineos]

I have following information:

and would like to calculate crc8 but somehow fail to get it working:

const result = crc.crc8(
    0x00, // polyLow
    0x31, // polyHigh
    8,
    0xFF, // initLow
    0xFF, // initHigh
    0x00, // XORlow
    0x00, // XORhigh
    false, // reflect
    Buffer.from([0xBE, 0xEF])
).toString('hex'));

Any pointer to where I'm wrong is appreciated. Thanks in advance.

[magiclen]

Modify polyLow to 0x31 and polyHigh to 0x00, and you can get the correct result.

[Sineos]

Thank you very much for your help. Unfortunately, I still seem to hit a road block.

I'm using your module in node-red and:
const result = nodeCrc.crc8(Buffer.from([0xBE, 0xEF])).toString('hex')
works and returns 1A.

Using

const result = nodeCrc.crc8(
    0x31, // polyLow
    0x00, // polyHigh
    8,
    0xFF, // initLow
    0xFF, // initHigh
    0x00, // XORlow
    0x00, // XORhigh
    false, // reflect
    Buffer.from([0xBE, 0xEF])
).toString('hex')

does not work and throws TypeError: failed to downcast any to Buffer
Since the first example is working, I concluded that the error is due to me messing up the usage, i.e. setting the wrong parameters.

Using:

• Linux 5.15.84-v7+ arm LE
• Node-RED version: v3.0.2
• Node.js version: v18.14.0
• NPM version: v9.3.1

[magiclen]

Use the crc function, not crc8.

[magiclen]

See: https://github.com/magiclen/node-crc/blob/master/lib/lib.d.ts

[Sineos]

D'oh! Now that you put me on the right track, it is quite obvious. Thanks!