PICAXE+ELM327

Code to flash to microcontrollers for interfacing into the CAN Bus.
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nr0x
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Joined: 2014 Jun 19 08:55

PICAXE+ELM327

Post by nr0x »

Since my bus switch grew into a different project, I figure this is the best place for it. The idea is to take a picaxe 20x2, and a HC-05 bluetooth adapter, and pair it with one of those cheap-o-matic OBD bluetooth gizmos that are all over ebay for under $10. For starters, the ELM327 is too slow, and just can't handle the quantity of messages that are flying around on a CAN bus. The buffer fills up in milliseconds. A better CAN interface would be..well...better. But this isn't about going batsh1t crazy. This is about working with what I have, cheap, and doing some cool stuff. One thing I want to do is to monitor specific bus data and pump it to an external display. This could give you extra gauges, or a heads up display using any old 4x20 LCD display. going the other way, I want to use the EVIC as a display for the picaxe. I also have visions of using the picaxe to add functions to the vehicle that I don't have now. For example, turning the radio volume up when you reach a certain speed.

For this project, I will be tinkering with the Interior bus, which I have connected to my OBD port with a DPDT toggle switch. I will post progress here as I get around to working on it. Like all my projects, I work on them when I have time, so don't expect this to be a start-to-finish thing.

NR0X
OBDRipper
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Re: PICAXE+ELM327

Post by OBDRipper »

Cool Cant wait , when's the first post ? :D

You might find this interesting ,https://www.youtube.com/watch?v=kJm9n7tTdHQ
I hacked an ELM327 by attaching the Arduino's Serial pins to the ELM327 board by by passing the USB bridge chip, then request data from the OBD2 port and display
things such as Speed, Coolant temp, RPM and a few other things, The ELM327 is fast enough to manage requested data, but yea like you say it not going to keep up when connected directly to the Interiour bus.

My Jeep unfortunatly does not have an EVIC where i can display my data which would have been awesome, So i'm forced to display it on an LCD, I used a 16x2 LCD.

Image
nr0x
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Joined: 2014 Jun 19 08:55

Re: PICAXE+ELM327

Post by nr0x »

Checking in. I have still been working on this here and there. But things took a slightly different path. My picaxe idea has grown into a picaxe+android idea, and I'm slowly developing an app and hardware mix to let me do cool stuff. The other day, I managed to remote start my jeep from my cellphone, via bluetooth. But the key has to be present for the skreem module, or it just dies again. If anyone is familiar with talking to or from the skreem module, I'd love to hear about it. The goal now is an android touchscreen, mounted in the dash. I've got a couple of suitable old phones that will run the app, and talk to the picaxe onboard through bluetooth. So it will be like a touch screen display for controlling different things in the vehicle.

I'm still here though. Still breathing. Just busy as hell.
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linuxkidd
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Re: PICAXE+ELM327

Post by linuxkidd »

This is EXACTLY what I want to do my '14 JGC... It has the 8.4" UConnect w/ Nav.. which is a complete PITA. I found (and ordered) the PAC RP4-CH21 and the PAC-UP which are supposed to allow controls of all the functions, except the vented front seats (which I cannot live without). Further, they achieve the controls by remapping the remaining dash buttons to other features (like back and screen off buttons to control heated seats or some such). My desire is to map out all the CAN commands for these features and have an Android App (ran via an HDMI Android Stick or similar) control the whole shebang.

I also want to fab up an Amplifier replacement that takes line level in, and can attenuate the input and insert the backup sensor / rear cross path / forward collision alert tones into the channel. A *very* marketable product would handle both discrete front/rear/sub inputs, as well as a single right/left input pair mixed out to front/rear/sub outputs (controlled over CAN bus from the stock head units for those that like that thing).

Let me know if you want some additional testing, etc... I'm planning to spend the next month hacking pretty hard on this.

I also bought a 3d Printer recently, and plan to use it to make a dash insert to adapt the 8.4" screen opening to whatever capacitive touch monitor I end up with.

LK

**Edit: I should also note that I have a WiFi hotspot that stays in the Jeep and can serve as my always-on internet for things like VERY remote start, vehicle tracking, etc.
nr0x wrote:Checking in. I have still been working on this here and there. But things took a slightly different path. My picaxe idea has grown into a picaxe+android idea, and I'm slowly developing an app and hardware mix to let me do cool stuff. The other day, I managed to remote start my jeep from my cellphone, via bluetooth. But the key has to be present for the skreem module, or it just dies again. If anyone is familiar with talking to or from the skreem module, I'd love to hear about it. The goal now is an android touchscreen, mounted in the dash. I've got a couple of suitable old phones that will run the app, and talk to the picaxe onboard through bluetooth. So it will be like a touch screen display for controlling different things in the vehicle.

I'm still here though. Still breathing. Just busy as hell.
If you can read this, the light is still red.
rtgree01
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Re: PICAXE+ELM327

Post by rtgree01 »

LK...

I have finished my latest board.... It uses a mbed microcontroller and has two CAN bus interfaces. It has a serial port that I use to control a directed HD radio device. I control the device with a ethernet port. The part that I wanted to share was that it has a TDA7719 (http://www.st.com/web/en/resource/techn ... 164982.pdf) That has 5 inputs that it can switch, front/rear/sub output or front/rear/2nd out. It is supposed to also mix any 2 of the inputs into the output channels. The TDA7719 has been used in a Kenwood head unit. The TDA7719 has a 3-band equalizer too. I have it in my Charger and because it is hooked up to the CAN bus, I don't even need my computer. I control it with my steering wheel controls.

Cool stuf with the PICAXE+ELM327... I have wondered what all can be done with some other equipment.

Ryan
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linuxkidd
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Re: PICAXE+ELM327

Post by linuxkidd »

Ok... the TDA7719 is a sexy little chip...

I'm gonna order a few of them ( in case I screw something up ) and ... grrr... I gotta fly out to SFO at 6am... I'll spend more time on this in a few days when I'm back..

Thanks rtgree01 and nr0x. I'd love to get more details about your circuits, code, etc... anything you're able to share.

I'd love to be able to control things via bluetooth.. Control via CAN is certainly valuable from a retail product perspective.. (i.e. drop in AMP replacement that provides perfectly flat output to an aftermarket amp, etc.. And even, since it's there.. provides the 3 band EQ :) )

We should do a hangout or phone call or something... talk through all this. :D

LK
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rtgree01
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Re: PICAXE+ELM327

Post by rtgree01 »

PM me if you want to discuss anything...
Ryan
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