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by borgel
2236 days ago
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Ahh, interesting. I can see how that combination of features would be easier to fit in an ASIC than as discreet components in the tiny dongle. Pretty cool hardware combination! Can you comment on what the safety/security/reliability blocks were? |
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- loss of ground
A vehicle OBD connector can at times, loose its GND pin. There are actually two GND pins - chassis and electrical that can sometimes disagree. Its possible for one of either of them to either (a) loose connectivity (b) bias towards the signal level or head towards a negative signal level (-2v was our typical observation).
To prevent an OBD protocol pin from dumping current down the channel, a complex HW/SW solution is needed to monitor and react quickly to prevent downstream ECUs from being fried.
- security
We built a custom debug tool based on CM-DAP (ARM debugger technology) that included OOB security paths to unlock a device for re-flashing / debugging. I think we made 500-1k of these in total for manufacturing/RMA/logistic purposes. This was super fun to work on :)