AUDI A4 flexray params estimation - nanamiwang/openpilot GitHub Wiki

FlexRay parameters decoded from pin3.psdata:

• gNumberOfStaticSlots: 51
• gPayloadLengthStatic: 17
• gdBit 0.1 µs
• pdMicrotick 0.025 µs

Parameters estimated from 20181220-0001 rs pin 3.psdata waveform:

• gdTSSTransmitter: 9

Time interval between last static slot and first dynamic slot 52( gdActionPointOffset or gdMinislotActionPointOffset)

9 µs / gdMacrotick

Time interval between last static slot 51 and dynamic slot 54, and no transmission on slot 52, 53

27 µs = gdActionPointOffset or gdMinislotActionPointOffset + 2 * gdMinislot

Time interval between dynamic slot 53 and dynamic slot 56, and no transmission on slot 54, 55

26.8 µs, DTS LOW of slot 53 is 600ns

Time interval between static slots (related to gdActionPointOffset)

9 µs / gdMacrotick

Length of static slot waveform: 43.2 µs

aFrameLengthStatic 432 gdBit

aFrameLengthStatic(gdBit) = config['gdTSSTransmitter'] + cdFSS + 80 + config['gPayloadLengthStatic'] * 20 + cdFES aFrameLengthStatic(gdBit) = 9 + 2 + 80 + 17 * 20 + 1 = 432

Suppose gdMacrotick is 1 µs/MT gdStaticSlot = 2 * config['gdActionPointOffset'] + ceil(((aFrameLengthStatic + cChannelIdleDelimiter) * gdBitMax + config['gdMinPropagationDelay'] + gdMaxPropagationDelay) / (config['gdMacrotick'] * (1 - cClockDeviationMax))) gdBitMax = gdBit * (1 + cClockDeviationMax) = 0.1 * (1 + 0.0015) = 0.10015

0.0 < config['gdMinPropagationDelay'] + gdMaxPropagationDelay < 0.5

gdStaticSlot_min = 2 * 9 + ceil(((432 + 11) * 0.10015 + 0) / (1 * 0.9985)) = 63 gdStaticSlot_max = 2 * 9 + ceil(((432 + 11) * 0.10015 + 0.5) / (1 * 0.9985)) = 63 So gdStaticSlot is 63

Time interval between dynamic slots (related to gdMinislotActionPointOffset) 9 µs / gdMacrotick

dynamic trailing sequence: slot id 52, payloadlength 4, period of LOW: 600ns slot id 64, payloadlength 9, period of LOW: 200ns slot id 65, payloadlength 17, period of LOW: 1600ns slot id 64, payloadlength 9, period of LOW: 8600ns

gdSymbolWindow + gdNIT > 20µs / gdMacrotick