Old BMS Hardware Thread

[GregsGarage]

In my application, I have a touch pad lcd screen, can I turn the screen to the video output or do I have to make an additional circuit?

Hi Francisco,

As Peter said the current versions display is a simple video monitor. In theory any serial display device could be used, but the software would need to be modified to suit and of course the board hacked to connect to it. What display are you thinking about? Do you have a link? I quite like the look of these; http://www.4dsystems.com.au/prod.php?id=113, but it would be a lot of work to implement. The master board at the moment is version 2, We are gathering ideas for Version 3 of the master. The SV2000 serial to video chip being used at the moment will most likely be replaced by a TellyMate, a cheaper and better serial to video chip. It could also be possible to design the board with a serial header and then build it as required.

[f.mendes]

Thanks for reply, both of you.

I'm using this one: http://ww1.microchip.com/downloads/en/D ... 51844a.pdf

At this moment this lcd screen is like an onboard computer, wich can display few things like speed, time and date, set of headlights, etc.

But this LCD is controlled by a PIC24 and I think it cannot be programmed by any below version PIC's.

The best solution was to have all the software controlled by the PIC24, but it's harder at this point (and you are doing an excellent job), so what i can do is control the LCD with PIC24 and try to send all the information from BMS to it. for that i have only to communicate with both PIC's (PIC16 and PIC24), probably.

There is another thing i want to ask you.

What is the very last versions of master and slave boards?

I assume that the master board is V2.0 from 21/08/09 and the slave board is V1.02 from 21/02/10, right?

And one more thing, just to give you some more info about my project.

It's a final project of course, and I'm doing an EV like a tricycle, where the traction is made by a dc brushless motor on the front wheel.

The motor is powered at 36 volts and has a power of 500 watts.

So i have 14Ah.

The specs. are a little diferent but it only affect the software right?

I'm here to help in everything I can, you can count on me.

What I cannot help, I will try to ask my coordinators, so we can solve few problems quickly.

Thank you,

Best Regards,

Francisco Mendes.

[GregsGarage]

If I understand you correctly, you have a working display that shows speed, time, etc. Is this code available and is the project on the internet anywhere? What would be possible is to feed a data stream from our master to your display. Then it is just a matter of writing the code to display the information. Also if you have time information we could use your display to calculate amp hours from raw amp data from the master. One problem that we are trying to tackle at the moment is an accurate state of charge routine which needs a accurate timing loop to achieve.

The master board is version 2, for the slaves you would want to use the 16 cell board. I am assuming you are using 12 cells for your 36 volt pack so you would build the board with only the first 12 positions populated. The software is written for a 100 amp current sensor, which should be fine with your 500 watt motor and the cell number can be adjusted in the menus.

Your project sounds like you are reinventing the Sinclair C5, any pictures?

[f.mendes]

I'm sorry the project is not on the internet, the code i can provide that but it is in C language, since i'm using a PIC24. To transmit a data stream i think it's not dificult, we just have to have all variables needed, but i don't know if the communication between different PIC's it's easy. In other simpler projects I had some problems with communications. But it's a matter of trying.

About the timing issue you have, why don't you use another timers besides Timer1, you still have Timer0 that works perfectly, and Timer2 too.

About the boards, i have some doubts, because i have done the last one you post here from slave, wich i don't know if it is correct.

I can't use 16 cell board since i have a space issue, i have to make different aspect ones.

the project is not like that you show me up. It's something like the picture I have in the avatar.

Francisco.

[GregsGarage]

Francisco,

The timing issue is probably simple for someone who does programming for a living, but that is not Peter or myself. We are always open for help and/or ideas. For now I am going to work on putting a timer in the watchdog which also has timer0, timer1 and timer2 like the master. Should learn a bit from that and since the program is simple shouldn't be too much of a challenge.

the project is not like that you show me up. It's something like the picture I have in the avatar.

Maybe like this? http://www.trikke.com/st01/electrichybrid.html

[f.mendes]

The project is something like that.

About the timers, I don't know how you are thinking to do it but if you are going to program a timer on the watchdog and then make the SoC in the master PIC, you probably have some timing errors, since you are always going to loose few miliseconds between communications I think. Or not? I'm not expert in that, but I had few problems in the past with timers and communications too, but not in PIC's.

There's other thing, I don't know if PIC16f886 fully works (and well) with more than Timer1, that's a thing I can search, but if you could have more than Timer1 working at the same time, the problem is simply solve, you just have to activate the other timer like you did with Timer1.

I don't know if you are understanding, my english is not so good as i wish.

Anyway, I'll try to see if we can have other timers at the same time.

Francisco.

[GregsGarage]

Any delay by using the timer on the watchdog pic to control the master pic loop speed will be the same each time through the program loop, so will cancel out.

Your English is fine, better than my Spanish? I am guessing from the name, where are you?

[f.mendes]

I did ask this afternoon about the use of more than one timer at the same time and they told me there is no problem on going that way. the only thing they told me was that it was better to use an external oscilator (crystal) instead of using internal oscilator and the master board has the space for it. And I asked what is better, resonator or crystal, and they told me that crystal is a lot better because of its resolution and the pin's are the same, OSC1 and OSC2 on the PIC16 (the thrid PIN is indiferent).

No Greg, I'm not from spain, they can't talk english very well. hihihi

I'm from Portugal.

Today I received a large order with almost all the components for the BMS, so i can start to build it today.

Regards,

Francisco.

[retepsnikrep]

Francisco. Do you not need the pcbs? Master and remote etc?

I have started on laying out my basic ideas for the v3 schematic i'll post it in a few days. I have reduced the component count quite a bit so far. I'm sorely tempetd to bin the analog temp sensors as we now have the I2C stuff working and can have multiple sensors on the same line, this also frees up another two I/O lines.

I'm not convinced yet about including ICSP pins for the watchdog or the tellymate on the board?
They won't change very often. Thoughts?

I would rather not use a crystal or resonator for the master chip as we will lose two inputs I think 8mhz is fast enough for our system and the error is minute as far as the accuracy of our crude calculations is concerned. I just need to do more work on the Timer as well. we will crack that in due course.

[f.mendes]

No Peter, i already have the boards done. thank you anyway.

About the boards you are using right now, what are the versions?

Slave board - V1.02 from 21/02/10 right?

Master board - V2.0 from 21/08/09 right?

About the crystal you don't loose any inputs. In the V2.0 Master board you have a resonator connected to pin 9 and 10 of PIC16F886, and if you put a resonator or a crystal it is in those pin's. So the space is already created. Right?

The only thing that crystal gives us is better precision on calculating time, better than internal oscilator. But it's about you. About the time issue Greg told me, do you think you can solve the problem? You just have to activate the Timer0 like you have done with Timer1, just the same way.

Regards,

Francisco.