IAC Firmware changes
PWM switched ground to pin1 and pin3 moves the valve to opposite directions, if pin2 has stable 12V+ supply. Connecting pin1 to GND closes the valve.
Control relatively simple. Some changes and things to-check required in idle_solenoid() :
- 2 channels must be used instead of config.iac_sol_channel. However, I don't see a reason to add a config variable to make them independent. Eg. config.iac_sol_channel and config.iac_sol_channel+16 would work well (that means if mdh02/mdh82 is used for one solenoid, mdh12/mdh92 can be used for the other).
- if one solenoid is powered, the other must be unpowered. This can be remembered or done dumbly every time (SRAM/cycles tradeoff).
- iac_conf can be cleaned-up (while merging the unipolar-iac support) as on GenBoard/UnderDevelopment/FirmWare/PowerRelated to make space for the new bit that activates BAC-mode.
Changed the end of idle_solenoid() in iac.c so it sets 2 output channels instead of one: \n
cli();
digitalout(config.iac_sol_channel, output);
sei_nop_cli();
digitalout(config.iac_sol_channel + 0x10, output ^ 0x80 );
sei();
config.iac_sol_channel has been set to 0x36 (stepper channel A)
This way 0x46 (stepper channel B) is inverted. Connections are according to GenBoard/Manual/DigitalOut/Table.
IAC control is somewhat working this way, I can use mdh/mdi commands and idle changes. For warm engine value around mdi70 seems a good approximation for 900 rpm. I've found that small changes to value doesn't reflect in rpm immediately (or at all). Big changes (like mdiff :) are noticeable promptly.
Idle controlled by GenBoard, but the idle controller (reference positions, ign-adv based control, iac-PID) is not yet tuned. Kindof instable now, see logs:
- [config.txt]
- [tables.txt]
- [ Config and data saved in MegaSquirt]
- [Datalog (XLS) from megasquirt. I've made a chart in it also]
Definitely relative heavy actuator couldn't cope with such a high PWMming (2kHz), decreasing control frequency was reasonable. MembersPage/BengtR measured frequency from couple of 'similar' (but different part ie. Bosch part number vice) valves, they all were controlled with 50 to 150 hz signals.
I've modified the firmware to call the idle solenoid code with 100Hz frequency (20 times slower, than original solenoid freq in GenBoard). It seems to be working now, changes like 1-2 (hex) iac values reflected quickly in rpm.