I have made up one of my new IMA control pcbs and can confirm the MAX 4619 solid state mima signal switching idea seems to work on the bench. It's passing through the pwm signals ok. The resistors on the bottom of the board are the fake MCM internal pullups for testing. I havent tried the cheaper CD4053 yet. I need to do some more work on my software but should be able to test the regen at idle thing properly soon.
Nice to get rid of the relays. Lots of work still to do to get the BCM gauge functions also working on the same board. Serial LCD works OK though.
Couple of pics. Note I off loaded some of the resistors from the 5 way toggle switch and the two way buttons from the steering wheel mounted control thread onto my new pcb. That makes the steering wheel buttons a lot simpler. So I may get to test the 5 way switch I mounted on the spare steering wheel soon as well.
I used 0.125w resistors which makes the board nice and small.
The 5 way switch now has an even smaller footprint with 4x 1k resistors soldered to the back. Seems to work well.
Cool. So I guess I've kinda missed something. You're creating your own version of MIMA? With integrated BCM Gauge functionality? That will be awesome.
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I will be developing by own ideas, and Mike and I are exchanging lots of info. Mine will probably not be available to purchase. I have no wish to tread on Mikes Mima toes, he is fully aware I'm working on my own version and have I been using it for a couple of years. This thread isn't just about my version of IMA control it's about anyones ideas of how to do it. Others are more than welcome to develop their own systems and I believe a couple of others have already done so.
The BCM gauge is still available while stocks last on the other thread.
I'm sure Mike's next version of Mima will be a tour de force in due course. Mike and I were both using relays on our previous versions of MIMA, this version uses solid state switching of the signals. It also uses a single 16F88 pic which has double the memory of the BCM Gauge 12F683 chip. It also has hardware usart for the serial comms with the lcd and bcm module. I'm hoping it will be a stepping stone to the full ODBII integrated system in a couple of years perhaps.
Seems to be working quite well BCM gauge data is working now
Chip is also doing IMA control as well. Need to try it in the car next week or so.
Video to follow later
Need to design some menus now to select various options like Max current limit assist/regen IMA etc. As we now have the accurate current data we can set out own limits.
This has also freed up one more input on the pcb which i could now use for MAP.
I have used 1620 words out of 4096 available so far in Pic Memory
It's now installed and running in the car with the 5 way button on steering wheel and BCM gauge function incorporated. I have run into the same problem as Mike though, some subtle change in the timing of the signals/switch overs means i now can't command regen at tickover So i need to carefully examine my two old working versions of ima control on the bench and compare it/them with the signals my nice new one sends out!!
Have to insert a few pauses and glitches i suspect to duplicate the old one LOL!! the new one is much more refined which is probably why it doesnt work!! ha ha
The MAX 4619 chip seems to work well for solid state MIMA signal switching!
Great progress Peter,
I will have to get some of those MAX 4619 chips, as the relays were one of the parts of the original systems that became obsolete.
The MAX4619 and CD4053 are analog switches.
Since the signals are all 5V logic, could you simply use 6 more pins on the processor?
Three pins would accept the Cmdpwr, and the two MAMODE signals ifrom the ECM, and send them back out to the MCM on three others, basically doing the MIMA signal switching right in the microcontroller?
I have been pretty busy, and have not sat down to compare the logic files as far as the regen in neutral issues. It must be something subtle.
Since the signals are all 5V logic, could you simply use 6 more pins on the processor?Three pins would accept the Cmdpwr, and the two MAMODE signals ifrom the ECM, and send them back out to the MCM on three others, basically doing the MIMA signal switching right in the microcontroller?
I don't think i can do this with my processor. No idea how? and I'm not keen to go for a bigger chip i'm aiming for a minimalist solution.
I need to sort the regen timing out then I can try a cd4053 chip as that is quite a bit cheaper than the max4619. if that works then the cost of the system will be minimal especially if i manage to power it from the MCM's own 5v supply.
I went on a 50 mile trip the assist side and the bcm display all work fine, regen does nothing although display indicates duty is changing etc Hmm!! I suspect I''ve been silly somewhere!! I'll study my captured data tonight.
Edit OK
Here's two lots of data for the Salea Logic Analyser
The first has been posted before and is from my old working IMA control with idle regen captured in the car.
I'll capture some clean data from this now it is back out of the car later!
1st one from my old IMA control captured data, shows change over from standby to regen at idle. 50% duty on left then gap in both pwm signals as duty is changed and relays switch over of about 1ms. I'll simulate this signal gap in my new system and see if that does the trick. Perhaps the mcm is seeing it as some sort of reset?
Second shot shows IMA signal when engine start commanded. Note MAMODE1 changes to 75% duty for approx 1 second. Engine starts within about 100ms
I might try sending the start engine signal today as well. See if I can start engine from button on steering wheel.
Peter,
Since the engine turnover is much quicker when using the stock system than it is with MIMA, the 75% may put the IMA into a high power mode.
That may get you some new capabilities with your power boost experiments?
I can try a cd4053 chip as that is quite a bit cheaper than the max4619. if that works then the cost of the system will be minimal especially if i manage to power it from the MCM's own 5v supply.
I finally found my HCTCD4053N CMOS chips today and tried one of them in place of the Maxim chip in my new IMA control board. Seems to work fine so that means parts are a bit cheaper still.
MAXIM 4619 IS £2.54 from farnell
HCT4053 CMOS version is 75p even cheaper on e-bay.
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MIMA Hardware Discussion
