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Board Overview (Firmware)
I/O
- CAN (inout)CAN
- Kill Switch (in) (?)Switch
- AFEs (iso-SPI) (inout)Fan Control (out)isoSPI)
- Fan Control
- Current Sense Board (out) (?isoSPI)
- Relays (inout)
Stuff that happens (Internal / Synchronous) that board needs to deal with
- CAN Message recieved
- Monitor Temparature (AFE)
- Too High→ increase fan speed
- Too low → who cares (?)
- Car powered on
- validate battery health / status
- turn on relays
- turn on current sense board
- Monitors state of charge
- Voltage
- Current
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- Kill Switch flipped (?)
- AFE Under/Over volt
- Disconnect relay
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- Three AFEs
- Temperatures measured via thermistors (AFEs)
- gpio's control the mux (for AFEs)
- adc: for reading measurements
- we talk to this bish the AFEs and Current Sense using iso-spi
- LTC6811 is the chip (Battery Monitor) (6811-1)
- According to the datasheet, the 6811 is pin and software compatible with the 6804 used in MSXII. The changes seem to entirely affect electrical characteristics.
- So we should be able to reuse the majority of AFE driver code
Questions
| Question | Answer |
|---|---|
| What are the conditions under which we open the relays? | Over current, over temperature, over voltage, under voltage, upon request over CAN |
| How many ways are there to change the relay state? Is BMS Carrier the only one controlling them? | Kill switch also controls the relay state externally. |
What are the incoming CAN messages? | BMS Carrier CAN Messages |
| What are the outgoing CAN messages? | BMS Carrier CAN Messages |
| What's the maximum rate we can have for voltage measurement? | |
| What's the maximum rate we can have for current measurement? | |
| What should it do when we power the car ON? | Check relay states and ensure the batteries are within manufacturers specifications for over voltage, under voltage, over temperature, etc. |
| How are we computing the SOC? | We will be using an OCV-SoC and coulomb counting method to start. (Ask Micah Black) |
| What are the temperature ranges for fan control? | An offset linear fan control curve to start for easy implementation. This will make the fans run at full speed before the batteries reach maximum temperature. |
| Can fan status be monitored? Does it need to be? (rpm too high/too low) | Yes, fans can and should be monitored to see any malfunctions. Specifications can be found here: https://noctua.at/media/wysiwyg/Noctua_PWM_specifications_white_paper.pdf |
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