Serial interface questions

General Megajolt Questions and Answers

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tetracanth
Posts: 2
Joined: Tue Jun 15, 2010 12:02 am

Serial interface questions

Post by tetracanth »

Hi all

I was wondering if it's possible to read some of the data from the MegaJolt lite's serial-out during operation using a device other than a laptop and the MegaJolt tuning software. I was hoping to interface a microcontroller to provide an in-dash display of some of the realtime data like the tach, advance, temp and load. Is the serial communications data format available publicly?

Spockie-Tech
Posts: 152
Joined: Wed Jan 02, 2008 12:52 pm
Location: Melbourne, Australia

Post by Spockie-Tech »

Indeed it is, I have done it.

You will need a transistor or RS232 Chip (Max232) to drop the +/- 12v out from the megajolt down to 0-5v for a micro.. going back the other way, the megajolt *will* read 0-5v signals (thats what I used), but if you're going to use a MAX232 chip, be nice use the Tx part as well and feed the 'jolt commands with correct-voltage-spec signals.. or do it the lazy way, both work :)

The Spec on the data format is here
http://www.autosportlabs.net/asl_dist/m ... n_v4.x.pdf

If you want to see what I did with an Arduino and some Nixie Tubes, look here
http://www.autosportlabs.org/viewtopic.php?t=2705

The Arduino software I wrote is available free from that thread to give you an idea on how to disassemble the megajolt status string. If you have any questions, I'll try to help.

regards
Brett

tetracanth
Posts: 2
Joined: Tue Jun 15, 2010 12:02 am

Post by tetracanth »

Fantastic: Arduino is my platform of choice, so that's going to be a great resource. Thanks for the link. At the moment I'm only planning on reading values: I'm new at this so I hope to avoid the risk of upsetting a critical vehicle system due to an error. I better get to reading your thread...


P.S. Thanks to the moderator who moved this to the correct subforum.

Funky Diver
Posts: 133
Joined: Tue Jun 08, 2010 7:06 pm

Post by Funky Diver »

Equally going to be doing "stuff" with ARduino, more specifically the Chips themselves. Using hte arduino to program the chips then mount them onto a combined board. Currently I have plans for 4 chips... looks like I might have t obe buying more :D

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