Battery Regulator- part 3
I have confirmed that the board programs and communicates correctly via serial with the Arduino environment. Almost everything is working as planned.
The timer that drives the PWM on pins 11 and 12 (ATMega168) or 5, 6 (Arduino), OC0A and OC0B, is used for system timing stuff too, so it doesn’t ever go completely “off”. I moved the optocoupler I noted was giving me problems with the ICSP to one of these PWMs- so once the PWM was enabled, it was never at duty cycle 0. That’s not OK, because then the shunt is always sucking a little current. So I need to move it. I think I’m going to move it to PD3 (OC2B) and move what was on there somewhere else. Makes stuff a little less neat, but I think it’s the best option.
Things that need doing in order to order more circuit boards:
- Verify correct operation of communication circuit
- Run long term (2hr) burn test at full shunt power to make sure nothing overheats, gauge the need for heatsinking the power transistor
- Fix power transistor footprint and redesign board and traces, make it smaller. Use 1/8 watt resistors where appropriate
Things that need doing after that:
- Test and plot linearity of analog optocoupler, adjust trimpots
- Get a feel for characteristics of pwm cycle control over shunt current
- Plan firmware
There’s a lot to do. I’m especially concerned with the eventual need to develop the “BatBuss” serial interface, loosely based on “EVILBus”. It’s going to need to be Bit-Banged, and I really don’t have a good idea about how to implement that yet. I’ll figure it out, and I actually don’t even need to to just get the regulators working, but I’m worrying about it anyhow. I also need to get an idea of the characteristics of the REGBUSS on the Manzinita Micro charger, and figure out how I’m going to effectively trigger it to go into Float and Finish modes. I think it will consist of some optocouplers and resistor networks, but I’m not sure yet. Need to test it, and to test it I need some guinea pig batteries and a current meter. An excuse to pick up a nice clamp meter? Possibly.