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I've got a set of 18s batteries, too. I've watched the install videos a couple of times. I think I'm up to the challenge. I've programmed Arduinos before and built other electronic kits. The high voltage scares me a bit, but hopefully my fear will keep me safe.
 

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2000 Honda Insight, 5MT
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Same boat as others, 4x18s, ardunio experience, light hvdc experience. I think you are making a smart decision with waivers and limited/no support for DIY installs, but still allowing it, in case there is no realistic option to locally meet with a CLC (since already own batteries)
 

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Cell balancing will be part of the MVP firmware, correct? I didn't see it on your "will include" or "won't include" lists.
 

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Discussion Starter · #704 ·
Cell balancing will be part of the MVP firmware, correct? I didn't see it on your "will include" or "won't include" lists.
Correct, and it's already implemented and working. The list I wrote up last night only includes unfinished features.
 

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Discussion Starter · #705 · (Edited)
In post #697 I described how the MEGA2560 can now boot in just 16 ms. That involved making a custom bootloader, and also changing the startup oscillator delay. Since then I've managed to I improve that time slightly, but only because it was low hanging fruit.

Recall that the primary goal here is for LiBCM to boot fast enough to start sending BATTSCI data to the MCM ASAP (to prevent a P1648).

Today I worked on the second part of that goal: rewriting the MVP firmware to properly handle booting into a condition where the key is already on; previously LiBCM expected to boot into a keyOFF condition, which was easy because during the next keyON event, LiBCM knew that all the signals had had plenty of time to settle... that's no longer the case now, so I needed to add some additional checks to ensure LiBCM does the correct things at the correct time, even with untrustworthy input signals.

It took a couple hours to properly handle the initial conditions, but at this point LiBCM can cold boot without generating any P-codes:

Tomorrow I'll test it in the car... it's past 4AM.
Edit: It works!:
Notes to beta testers:
-I also verified that the latest firmware (discussed above) will work with the existing Arduino Mega units you have now.
-The cold boot functionality I show in the above videos will not work until I send you a new Arduino Mega (with my custom bootloader and fuse settings).
-If you know how to use an ICSP, you can update the bootloader & fuses yourself (using the instructions I provided in our private chat). I don't expect y'all to do this, but if that's a trivial concept, knock yourself out.

...

With that out of the way, tomorrow I'll finally start the RevC PCB (which I'm hoping to order by SEP19).
Edit: I just started the RevC schematic five minutes ago.
 

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Looks like you do your best work between 11 a.m. and 4 a.m.;)
 

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Discussion Starter · #710 ·
Just want to mention (again) how frustrating it is buying parts right now.
Raw digikey search yields 2000+ parts. Click "in stock" and now we're down to 22 parts.
That is all.
 

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Gosh, maybe I should start reselling my resistor supply;)
 

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Discussion Starter · #712 · (Edited)
I'm just glad I'm not beholden to lead-free parts... yum yum leaded parts are about the only thing I can find in stock right now.

And the holes aren't the right size... so (at least initially) I'm gonna have to drill each one out. Clawing my way to the finish line.

Manufacturers being all like "Oh mudder, you want the crimp-terminal, the housing, AND the mating connector? Ur so needy... Good luck, bro. True story fo shizzle. Haha, gg".

Can we go back to just hoarding toilet paper?
 

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Discussion Starter · #713 ·
Just finished the RevC schematic. Key changes:
-More LPF filtering (I2C, SPI, temperature, etc)!
-I2C pulled up hard (1k24)
-added a buzzer (to a PWM)
-added QTY3 battery core temperature sensors... ended up having to use a surface mount connector (which I hate), but I just couldn't find in-stock thru hole connectors anywhere.
-swapped several pins around for routing/PWM
-added latching right angle ribbon cable headers
-serial display port now accessible from the top, with shrouded connector
-LiBCM turns on automatically when you turn the IMA switch on (versus having to turn the key on)
-various idle power reduction (e.g. blocking diode @ grid charger, switchable BATT/METSCI biasing, etc)
-New +5VP rail that LiBCM can turn off to save power (while still keeping itself powered).
-consolidated BOM (reduces unique part numbers)
-redesigned isoSPI (identical to reworked RevB PCBs)
-improved MCM'E' voltage spoofing circuit.
-reduced cell BMS LPF (to reduce noise)
-battery current sensor opamp is better balanced (for high frequency noise rejection)
-slightly reduced battery current sensor gain (to ensure we don't rail at max assist/regen)
-VPIN spoofing now has less noise (PWM no longer tied to static PWM frequency).
-removed SPI traces from OEM BCM connector (reduces noise); replaced with an unsoldered 0.1" SPI SIP.
-HLINE termination now 100 Ohms


In total, I added more than QTY100 new parts (RevC is up to QTY692 parts total).

Question to @Mario: Previously you had suggested changing METSCI termination on LiBCM to 2kOhm. I believe this was because the instrument cluster already has 120 Ohm termination, as does the MCM. I've left it at 120 Ohms (because it works)... but will change it to whatever value you recommend (just a BOM change).

...

As always, I'm open to feedback. I'll begin layout tomorrow, but it'll take a couple days to finish, so let me know if you find anything wrong.

If you want to cram any features on it, let me know your ideas and I'll see what I can do.
One feature I haven't committed to yet is moving the LEDs so they're visible from the top... if there's room after I place everything else, we'll see how many can move up. I agree this is a useful feature, but I need to make sure everything else fits first.
 

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One feature I haven't committed to yet is moving the LEDs so they're visible from the top... if there's room after I place everything else, we'll see how many can move up. I agree this is a useful feature, but I need to make sure everything else fits first.
Just a thought .. If useful .. Instead of moving the LEDs themselves , you could just move their output light to a different location with a fiber optic cable.
 

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Question to @Mario: Previously you had suggested changing METSCI termination on LiBCM to 2kOhm. I believe this was because the instrument cluster already has 120 Ohm termination, as does the MCM. I've left it at 120 Ohms (because it works)... but will change it to whatever value you recommend (just a BOM change).
Pretty sure I said that because I didn't know what I was talking about at the time, hah. The METSCI termination resistor should be 100 ohms, as is present on the cluster and what must be the characteristic impedance of the twisted pair. You should be able to look in the stock BCM and confirm it's 100 ohm as well. That's how RS485 works, some impedance of a twisted pair and that same resistance present at both physical ends of the bus.
 

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Circuit component Electronic component Cable Computer hardware Electronic engineering


I did this for my serial display today. Will something like this work for Revision C? (I'll put a USB A cable between those two breakout boards. The one on the left attaches to LiBCM.)
 

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Discussion Starter · #720 ·
View attachment 92421

I did this for my serial display today. Will something like this work for Revision C? (I'll put a USB A cable between those two breakout boards. The one on the left attaches to LiBCM.)
It's great for RevB PCB. However, RevC PCB will use this connector, which will be accessible from the top of the pack, even after it's installed in the car. Thus, a separate solution (like the excellent one you've just shown) won't be required.
 
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