Master Board Version 3

Threads relating to the BMS system begun by Peter Perkins

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retepsnikrep
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Re: Master Board Version 3

Postby retepsnikrep » Wed Jan 12, 2011 5:43 am

Fibre optics is a nice idea keep us updated with that.

The diodes are supposed to stop the input line going more than .5v more than the supply rails in either direction.
They should help with interference/spikes.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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dillond666
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Re: Master Board Version 3

Postby dillond666 » Fri Feb 04, 2011 8:30 pm

Referring to the feature list on page one.
5) Auto power off option once charging complete. BMS powers down after charge end. Save aux battery power. Possibly power BMS from main pack? Once BMS has turned itself off can't restart without operator input.

For my BMS effort I am intending to have a 12v wallwart thingy connected up to the same mains input on the car that the main charger uses. This will go through a diode to the master board. When the car is plugged into the 16amp socket to charge, the wallwart will power up the master and also make the "charger connected" input on the master go high. The master will then initiate the charge. When the charge is complete the master will switch off the charger but the master will stay powered by the wallwart until the charger cable is unplugged.

Note: The master live power is not permanently hot on my car.
The master power input from the car fusebox also goes through a diode so that the wallwart can't backfeed into the fusebox!
If your master is permanently hot you'd have to ensure the wallwart voltage was higher than the SLI battery voltage or your SLI would be flattened and the wallwart would do nothing.
Just to be clear, that means two +ve wires to the master, each with a diode :)

Derek

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Re: Master Board Version 3

Postby retepsnikrep » Mon Feb 28, 2011 6:31 pm

Here is an updated schematic of the proposed V3 Master board.

http://www.solarvan.co.uk/bms/MasterV3_16F1939.jpg

It now contains Auto BMS off function and Meanwell charger bulk & balancing current control.
It also has and aditional serial 16x2 lcd output for a simpler display if reqd.

Comments and error checking please. It's important we get schematic right :shock:

We still have three unused I/O on PORTA so i'm open to further ideas. 2 have ADC functionality one is simple i/o.
I can bring them out to simple connector and people can do what they want later if we don't get any concrete ideas.

I'll produce a combined 5 way switch/button/led pcb as well shortly. The master is now started by a simple press button and then kept alive by the Pic driving an opto controlling the pnp switch transistor. When pic output goes low BMS turns off.

Edit Just thought i could add an opto inteface Rxd/Txd connector using the cheapo fibre circuits that have been discussed on the other thread. Derek? How about it? It could just mirror the slave and master buses. An option for the really noisy cars!!
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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dillond666
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Re: Master Board Version 3

Postby dillond666 » Mon Feb 28, 2011 8:22 pm

i could add an opto interface Rxd/Txd connector using the cheapo fibre circuits that have been discussed on the other thread


Sounds like a plan :D I'm going to use it on my slave bus.

Derek

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Re: Master Board Version 3

Postby dillond666 » Wed Mar 02, 2011 11:46 am

Comments and error checking please. It's important we get schematic right


Peter,
I still can't make proper sense of the master input on your schematic. If the idea is to prevent the Pic input from coming within a diode drop of VDD and GND to prevent latchup I would like to submit my idea for consideration. This would keep the bus 0.6v within the power and ground rails and would prevent any large induced spikey things....I think .

Derek

EDIT: removed huge drawing and put up smaller one. Changed some words too.
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Re: Master Board Version 3

Postby GregsGarage » Sun Sep 11, 2011 1:23 pm

A while ago the Maximite project caught my eye and I posted that it could be a candidate for use as a master. This is what I said;
The Maximite is a Pic32 chip with a basic interpreter programmed in. Output is composite video (or VGA) and input is a ps2 keyboard or usb. It also has a SD card slot for loading programs and storing data. What he has done is recreate something like the old TRS80 computer on a Pic32, including a BASIC interpreter that has line numbers :!: , how retro can you get, but with the added benefit of 20 I/O pins from the pic being available. Yes the interpreted basic won't run as fast as a complied program, but this is a 32 bit 80mhz processor. And being able to program your master software in a free version of basic is nice, but with this you don't even need a computer to do the editing, just plug in a keyboard and away you go. At the moment though it has one glaring omission, no serial comms. :( But he has said this will be added in a firmware update, so I will keep an eye on this project.


Yesterday V2.6 of the firmware was released and the Maximite now has 2 serial ports, SPI and I2C support. :D Sadly no Dallas one wire support (yet?) so the temp sensors we are using won't work, but I haven't been particularly impressed by them anyway, they are pricey at around £3 each (not much individually but if you want to use 10 of them it starts to add up) and suffer from interference on my Matiz under hard acceleration. This project has definitely grown some legs, a number of expansion boards are available and has a very active community also releasing code (one person has even replaced MMBasic with UNIX :shock: ) But the MMBasic is what I am interested in. It has 2 types of variable, string and float, so none of the fancy hoops to go through making sure integer maths don't overflow. 8) It also has timers, frequency counters, etc. all available. No more having to set config bits or learn the intricacies of a different pic micro. Basically the code needs to be ported from pbp to MMBasic and an expansion/interface board made to go between the maximite and the vehicle. Future or different versions of the master would only require changing the interface board and updating the code instead of a complete new pcb.

I am tempted to purchase one and start some coding, but will resist the urge for the moment and get some other projects done first. :(
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

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Re: Master Board Version 3

Postby retepsnikrep » Sun Sep 11, 2011 4:13 pm

The temp sensors are I2C so should work?

Sounds intriguing have a go Greg by all means.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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Re: Master Board Version 3

Postby GregsGarage » Sun Sep 11, 2011 5:17 pm

I thought the temp sensors were Dallas one wire and that it is different than I2C. :?

I think I will order a maximite next month and have a play.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191


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