Rylin’s Questions:
- Timing to ensure we send accurate data
- Do we receive an ACK bit at the end of each transmit
- Standard or extended CAN frame?
- Request based or constantly sending info?
- Will EPS or CDH have priority over CAN bus or will it depend on message type?
- Meeting possibly on the 30th or 31st of Jan
Rylin’s Answers:
- The EPS STM32 does not have its own CAN module/controller
Shreya’s Questions:
- Does the cdh mcu have a can controller?
Daniel’s Answers & Questions:
- We haven’t selected a bit rate yet. Haven’t determined the propagation delay either.
- If the EPS controller sends a message to the RM46, the RM46 will set the ACK bit in the message frame if it was received.
- I would say standard frames. Since we don’t have many messages anyways, I don’t see any benefit in using extended CAN when it’d mean more data would have to be sent over the bus.
- Request-based versus constantly sending data
- Some of the key considerations include:
- The data needs to be accompanied by a timestamp for telemetry purposes.
- The data needs to be collected in specific time intervals for telemetry purposes. How often will you be collecting this data for EPS-related purposes? If it’s at a much higher rate than telemetry, we’d have to discard a ton of data.
- EPS board doesn’t have persistent data storage, so if the MCU gets reset, we lose any data that was in RAM.
- Need to deal with the situation where the CDH MCU is doing something important and EPS sends some data. If the message is handled in a high-priority interrupt, that could cause some issues.
- <There’s probably more I haven’t thought of yet>
- Priority should just depend on the message type.