battery monitoring with opto-isolators

[reloadron]

Just for the heck of it I ordered a few PICs to mess with. Using analog opto-couplers never did seem to work out right. Every combination I tried had really poor linearity as can be seen by by earlier science experiments. I like MrAl's approach using a PIC.

I had looked at the MCP3002 which can be found HERE because with 2 channels of ADC it can be used with a differential input but settled on some PICAXE 08M chips to experiment with. I figure I should have the parts by this weekend if all goes well.

Ron

[MrAl]

Hi there,


So you are not going to use a regular ol' PIC chip?

BTW, if you decide to use an external AD like that chip you will also need a uC chip to go with it,
one for each channel, which makes the requirement step up to two IC chips per channel.
Also, you may wish to go to 12 bit if you do decide you want to use an extra AD chip like that one.
I think the cost would be about the same.

[kheston]

Ron,

The PICAXE 08M is a 12F683, the 12F683 is what I'm using. I smoked three 08Ms playing with a desulfator MrAl was coaching me through building (no, he didn't coach me on how to fry chips). They're great chips, easy to program, but they smell funny when you pass 48v through them. I decided after frying them that the less user-friendly/cheaper versions without the PICAXE firmware was a better route for me.

Enjoy!

[reloadron]

Why a PICAXE chip? Actually because in talking to one of my vendors I mentioned them and the vendor told me they would sample out several to me just as a favor. I figured free was a reasonable cost.

I did look at the PIC12F675 and the PIC 12F683 briefly and may snag a few of them. I think they are just over a buck each from Allied who I deal with quite a bit. I never worked with a PIC so I figure it could be interesting. Most of my A/D applications just require buying an off the shelf module and writing some very simple VB code to get what I need. PIC is something I have wanted to experiment with so I figure why not? Old dogs can learn an occasional new trick I think.

Ron

[MrAl]

Hi there,


I just wanted to mention that the PIC's are not terribly hard to work with, but you do have to pay attention
to most of the registers in the particular chip because they do interact to some degree. If one register
has a bit set (or not set) it may affect the whole operation when you go to do something with it that seems
to not have much to do with that register. If you review all the registers at least once i think you would
make out pretty well. There is also a complete forum dedicated to PIC's alone.
It's also probably a good idea to start with a short program that just blinks and LED or something just
to get familiar with everything. There are a few tricky things to learn
A program without interrupts is also a good idea to start with.

[reloadron]

Well I got some presents in the mailbox today so this weekend I will begin PICs 101 I guess. Yes, I plan to start slow and ease into this stuff. Somewhere around here (the infamous somewhere) I have a breadboard I can use. I have also been doing some reading.

For some reason this project thing just has me interested in using a PIC. Funny but I will likely rejoice at the first blinking LED.

Ron