Old BMS Hardware Thread

Threads relating to the BMS system begun by Peter Perkins

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Re: Old BMS Hardware Thread

Postby GregsGarage » Thu Dec 20, 2012 7:49 pm

I've been using Itead and have no complaints. They aren't the fastest, but most of that is the shipping, however the price is right and they did reject one of my early Gerber files because it didn't look right. Turns out I did manage to leave off a footprint, so they do check for basic errors before getting the boards manufactured. 8) So if you are in a hurry consider another service (or maybe they have a faster shipping option)

We have been talking a while about doing a V3 of the master. Main problem with the V2 is the propetary serial to video chip is pricy. There are better options now available, 2 at the top of the list is the Tellymate serial to video converter and the Maximite which I am working on using with my 6802 slaves. In theory I will have a fully built V2 master and slaves availible when I get the 6802 working, but no promises as to when this will happen.

EDIT: Slave Ver 2 files are now in the relevant thread.
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Re: Old BMS Hardware Thread

Postby casemod » Sat Dec 22, 2012 2:06 am

GregsGarage wrote:I've been using Itead and have no complaints. They aren't the fastest, but most of that is the shipping, however the price is right and they did reject one of my early Gerber files because it didn't look right. Turns out I did manage to leave off a footprint, so they do check for basic errors before getting the boards manufactured. 8) So if you are in a hurry consider another service (or maybe they have a faster shipping option)

We have been talking a while about doing a V3 of the master. Main problem with the V2 is the propetary serial to video chip is pricy. There are better options now available, 2 at the top of the list is the Tellymate serial to video converter and the Maximite which I am working on using with my 6802 slaves. In theory I will have a fully built V2 master and slaves availible when I get the 6802 working, but no promises as to when this will happen.

EDIT: Slave Ver 2 files are now in the relevant thread.


Thanks,

Yes I have been reading about it.
I will look into the files tomorrow, not in a hurry.
So are you planing to do a V2 with the new Video chip, or going straight to V3?
If the changes werent that many you could always build a small PCB to interface from serial to the LCD.

BTW my conversion is here:

http://www.diyelectriccar.com/forums/showthread.php/conversion-vw-polo-ac-industrial-motor-78701.html

One usefull feature for V3 would be an auxiliary port to communicate with the acessory 12V battery and trottle the power supply. It could be usefull for those that run acessories from the 12V pack (Inverter, mini fridge...) and need to keep a log of it.

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Re: Old BMS Hardware Thread

Postby isaac_alaska1 » Mon Feb 18, 2013 2:47 am

I am still having trouble getting these new slave boards working. i haven't been working on them a lot, but a bit here and there. the problem seems to be somewhere in the slave boards, cause i can get accurate results using a tested-good slave board. the problem is that the first cell reports accurate voltage, and then cells after the first one periodically report lower voltages than the actual number. what should the slave bus signal look like with three cells? with the working slave board connected to three cells, i see three packets of data sent every second. they are identical. i've attached these below.

well i was going to attach images but it won't let me attach anything. perhaps i can zip them all together in a minute if it will let me attach a zip file.

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Re: Old BMS Hardware Thread

Postby isaac_alaska1 » Mon Feb 18, 2013 3:24 am

*edit*
i'm reading data on the slave bus at the third cell (commands to slave #3) and on the master bus. what i'm seeing is that on times when the voltage is reported correctly, slave three receives a command that looks like 110111111111110 (i'm estimating this based on time divisions of my scope) and all three cells report accurate voltage.

on times when the voltage is reported incorrectly, slave 3 receives only a high pulse (111111111111110) and slave 1 reports correct voltage but slave 2 and slave 3 both report 111111111111000 on the master bus.


i think i'll just make a video of what's going on and post it to youtube. might be a whole lot easier to track what's going on.
i have it set up so i can read data from any point along the slave bus, as well as read data on the master bus, and i have a dual channel scope so i can take master and slave readings at the same time. is there anything i should make sure to capture in the video?

-Isaac

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Re: Old BMS Hardware Thread

Postby retepsnikrep » Mon Feb 18, 2013 5:23 am

You need a logic analyser the scope is only of limited use.
Regards Peter

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Re: Old BMS Hardware Thread

Postby isaac_alaska1 » Mon Feb 18, 2013 6:56 am

i have access to logic analyzers but i've never used one. i can learn though. what all signals do you want to see? all three slave bus commands and the master bus data?

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Re: Old BMS Hardware Thread

Postby GregsGarage » Wed Feb 20, 2013 6:00 pm

Just think of a logic analyzer as a simple scope with no voltage scale to adjust and the time scale is adjusted by sample rate. It will decode the bits and give you a display of the data and also allow you to see the timings between signals being sent. Just watch when connecting to slave busses, all connections should be at the same voltage potential.
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Re: Old BMS Hardware Thread

Postby GregsGarage » Wed Feb 20, 2013 7:11 pm

Look at the master bus with the logic analyzer. Compare the data being sent on the master to what you are getting on the display. Slave bus can be checked by sending command 7.
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Re: Old BMS Hardware Thread

Postby isaac_alaska1 » Thu Feb 21, 2013 12:38 am

the problem seems to be on the slave bus. the command being sent from the master board to the first slave is good, but the command being sent to the second slave is problematic. the width of the high and low pulses are not quite right. a high pulse (1) should be 104 us, and a low pulse should also be 104 uS. the command being sent into the second slave begins with a high pulse followed by a low pulse. the problem is that the high pulse is about 134uS adn the low pulse is only 70 uS. i think sometimes it's being interpreted correctly and sometimes it's mis-reading it. it seems to be a hardware problem not letting the signal fall off as fast as it should, but i'll be hopefully doing some more tests on it today to try to figure it out.

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Re: Old BMS Hardware Thread

Postby GregsGarage » Thu Feb 21, 2013 8:30 am

Sounds like the problem is in the slaves. Are the config bits set correctly? Load up the hex in pickit 2 and post the config bits shown in top right corner.
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