# Using reset pin of OEM EV inverter cpu to clear the way for external brain control



## Amberwolf (May 29, 2009)

This post:
https://openinverter.org/forum/viewtopic.php?f=10&t=575&start=10#p7771
notes that it is possible to use the reset pin of the CPU of an OEM inverter to disable that cpu, to allow wiring in an external brain control, presumably without having to hack at the traces and wiring (as much, at least, and hopefully not at all) of the inverter/powerstage board.



Jack Bauer said:


> Pin 124 of the TMS main processor is the reset pin called XRS. Pulling that to ground puts Elon asleep and leaves everything else up and running.


The images from that post are attached here, showing the reset pin wiring, and the CPU in reset and running states. (note the LED next to the red wire; the wire itself is being used for the reset). 


Most CPUs and other microcontrollers i've dealt with will tristate their i/o pins (at least the outputs) when held in reset, so they won't interfere with anything else that is on the same bus, etc. So this seems like the easiest and most reliable way forward; less risk of damaging anything else in the inverter while zombifying it prior to external brain installation.

My project (the SB Cruiser trike here: https://www.endless-sphere.com/forums/viewtopic.php?f=2&t=67833 ) will be using a pair of Honda IMA inverters, more because of size than anything else, as I don't need the kind of power the larger inverters provide, and they should be significantly smaller and easier to use on my small trike than the others (though i face other challenges like weatherproofing). While i will be using the Lebowski SMD brainboard to run the powerstages, this technique should apply the same regardless of brain used. 

I have been looking around for a week or so now, and not yet found which CPU the Honda IMA inverter uses, to then find a pinout for it, and thus locate the reset pin. Tomdb's posts over here:
https://www.diyelectriccar.com/forums/showthread.php?t=163650
have some good pics of the insides, but the numbers are not readable on the CPU. I have a couple of the inverters on the way, and they should be here "soon" but with the covid19 stuff going on, there aren't any arrival time guarantees. So in the meantime I'm gathering as much information as I can, to speed up the process of developing the "system" to turn these into controllers i can use on my trike.


If anyone has any of that information handy, it would be helpful to me (and others that may also use this inverter) in going forward on this project. 



If not, and assuming the pinout is not available anywhere once I do know what CPU it uses, I can probably locate the reset pin experimentally, using an oscilloscope to monitor a data or clock line (which might be obvious from component connections once i see it), and then grounding steady-state pins on the unit that are not Vcc/etc lines, until such signals are stopped, but resume when the grounding is removed. 


(Note this thread is a crosspost from https://openinverter.org/forum/viewtopic.php?f=9&t=699 , but that forum is specifically for the Openinverter project, and also does not cover the Honda IMA as a powerstage, and so I am not expecting a reply over there (but will post any results I get to that thread for Openinverter users). DIYElectricCar forums has dealt with both the Honda IMA and the Lebowski brainboards, hence the crosspost. I also crossposted it to my "home" forum of Endless-Sphere, so that I can keep all the results there as well, for those that don't visit DIYEC or OI forums but want to do this sort of thing. https://endless-sphere.com/forums/viewtopic.php?f=30&t=105707 )


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## rmay635703 (Oct 23, 2008)

I would recommend talking to mudder who redesigned the BOM/mcm/etc with his own design

https://www.insightcentral.net/threads/focus-group-which-drop-in-lithium-cells-to-use.82201/page-29

And also to retep who has reversed the module communication 

https://www.insightcentral.net/thre...lls-can-it-be-done.125935/page-6#post-1458906


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## Amberwolf (May 29, 2009)

Thanks. I couldn't create a login to post the question on that forum; it keeps prompting me for Facebook login, which I don't have (and won't create).

But the inverters arrived today, and the pin was located. Haven't got any further than that.
https://endless-sphere.com/forums/viewtopic.php?f=30&t=105711&p=1547401#p1547401


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## rmay635703 (Oct 23, 2008)

Amberwolf said:


> Thanks. I couldn't create a login to post the question on that forum; it keeps prompting me for Facebook login, which I don't have (and won't create).
> 
> But the inverters arrived today, and the pin was located. Haven't got any further than that.
> https://endless-sphere.com/forums/viewtopic.php?f=30&t=105711&p=1547401#p1547401


That is very strange, I don’t have fbook and have an account there.

Sadly the forum owners there as here have been ruining things recently

It appears on 2nd check that it just says use fbook to sign up faster.


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## mudder (Apr 20, 2020)

Hello, I have already completely reverse engineered the entire G1 Honda Insight MCM. I've also created a drop-in replacement PCB that allows complete control of every single OEM function using an off-the-shelf Atmel microcontroller. It's been a couple years since I touched that project, but the hardware solution is complete... I didn't get around to writing the firmware yet, because I've been busy with other things (for several years now, sadly).

This information is all publicly available on insightcentral.net. Everything I do is open source, including this design, which I call "Linsight". If you want to roll your own solution, then you could look at the complete pinout spreadsheet I created, which contains a detailed description of every single wire in the OEM IMA bay. Again, this is available at insightcentral.net


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## MattsAwesomeStuff (Aug 10, 2017)

mudder said:


> Hello, I have already completely reverse engineered the entire G1 Honda Insight MCM. I've also created a drop-in replacement PCB that allows complete control of every single OEM function using an off-the-shelf Atmel microcontroller.


Wow, I've never heard of this before.



> This information is all publicly available on insightcentral.net.


Vertical Scope took away the ability to search for threads started by a user. So the only option is to endlessly scroll through posts you've made, without being able to jump to a specific point (you literally have to scroll through them and pause for it to auto-load the next set, no indexes). Do you have a main project thread or some quicklinks for us to follow?

I'd love to share this and bring it up as an option for people.


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## Amberwolf (May 29, 2009)

Thanks, Mudder! 

I had actually already found the Linsight project on InsightCentral, while searching for IMA information in general, and again when you were pointed out as a possible source of information, but I could not find one place with the info, and as pointed out above, the search function is less than helpful, at least not for non-members.

After I found myself unable to create a login without going thru facebook (no, i don't know why the regular login link doesn't work, but it just redirects itself to itself forever when I click it), I spent time over several hours (though not all of that several hours doing just this) slogging thru posts and threads one at a time to find the data, but didn't manage to locate relevant stuff, though there is certainly plenty of discussion of the system.

I did try using Google to search the site, but it didn't work very well for the stuff I'm after. 

If you could link to a post or set of posts that contain the information, that would be very helpful.

If there is an external wiki or github-like page with it, that would be helpful as well.


Basically the project I am doing is completely bypassing (disabling) the inverter's own CPU, and directly controlling the powerstage gates from the Lebowski brain. 

The Lebowski brain will run just about any three-phase powerstage and motor; it has an autotune function and can be manually tuned to correctly run the motor.

In my case, since I am not using the OEM motor (or any other OEM part besides the Inverter itself), the inverter's built-in CPU does not know how to run the motor I am using. AFAICT the inverter cannot read the "three hall sensor" (UVW) type of position sensing, and instead uses a resolver of some type on the OEM motor. So the built in CPU can't detect the position of the motor I'm using, and thus can't run it, even if I had a way to convert my throttle signal (and separate analog brake signal) to a set of commands to the built-in CPU. 

Hence using the Lebowski brain to bypass all that, and convert my throttle/brake signals into gate signals for the IGBTs to run the motor. (the Lebowski brain also can read the halls in my motor for startup, then run sensorless after that).


Anyway, the complete project thread is on Endless Sphere over here:
https://endless-sphere.com/forums/viewtopic.php?f=30&t=105711
and will, when completed, be a how-to for DIYers wishing to build their own similar system from the Honda IMA Inverter and Lebowski brain.


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## rmay635703 (Oct 23, 2008)

Mudder is busy, you will need to contact him directly 



Part positioning

https://www.insightcentral.net/attachments/insight-ima-wiring-zip.52905/

https://www.insightcentral.net/threads/focus-group-which-drop-in-lithium-cells-to-use.82201/page-13


Related software
http://www.uniti.earth/product/uniti-arc-microcontroller/


Useful discussions 

https://docs.google.com/spreadsheets/d/15fwpR418Kc8VwTdCHOV5z4948UoCgKYjfq-KpJiI8Lg/htmlview

https://www.insightcentral.net/threads/focus-group-which-drop-in-lithium-cells-to-use.82201/page-12

https://www.insightcentral.net/threads/focus-group-which-drop-in-lithium-cells-to-use.82201/page-11

https://www.insightcentral.net/threads/focus-group-which-drop-in-lithium-cells-to-use.82201/page-8

https://m.youtube.com/watch?v=kAznO_p_rEY

https://www.roadandtrack.com/car-cu...-honda-insight-is-the-first-hybrid-tuner-car/


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## mudder (Apr 20, 2020)

Here's a github repository I just created that summarizes the OEM G1 Honda Insight's entire IMA wiring diagram, including information on every single signal. I've also included introductory Linsight-specific information, but NOTE LINSIGHT IS NOT A FINISHED PRODUCT!

https://github.com/doppelhub/G1_Honda_Insight_IMA

These are my personal notes, and are not written for a general audience. However, I tend to be quite thorough, even in my personal notes. If nothing else, this information should give you a huge jump start on your project. 

...
I read over your project for about 2 minutes. Here are my thoughts based on what I saw:

If you want to control the IGBT driver module (inside the PDU), then that's only maybe a dozen or so signals routed from the MCM to the PDU igbt driver.

The three hall sensors are 20 degree offset (instead of typical 120), and need to be powered by 5 volts. The complete pinout is available at the above github project.

...

Unfortunately, my schedule stays VERY full. Therefore, I will not be posting any further replies to this thread. If you need to contact me, please do so via github (user doppelhub) or insightcentral.net (user mudder). I don't guarantee I'll be available there, either, but those are both sites I already use often. 

Good luck!


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## Amberwolf (May 29, 2009)

Thank you both very much for the information links; I will read thru it all and see what parts are useful.


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