MINI COOPER S OBoarDuino

[lamb.chop]

This is my plan & build thread for my OBDuino32k clone going into my 2003 MINI COOPER S.

Building blocks are :-

Boarduino Boarduino (Arduino Clone) Kit (w/ATMega328) .omlout:. nice & small



LCD eBay - The UK's Online Marketplace orange on black, same as the OE instruments





bracket Attach a Boarduino to a 16x2 LCD by OSU_FYE - Thingiverse should keep everything tight & small, made



ISO interface http://cache.freescale.com/files/ana...et/MC33660.pdf ordered 5 samples, received yesterday

Casing http://www.supertronic.com/files/d5e...027d89bafd.pdf already got one, nice & small & neat



Schematic



Waiting on LCD to arrive from China..............

[msc]

I would suggest going with an Arduino Nano rather then the Boarduino. I looked into the specs for the Boarduino and it uses a Ceramic Resonator rather then a Crystal for it's reference clock. With the ceramic resonator for timing the base accuracy is less and there will be greater fluctuations in accuracy with temperature. Since you probably already have the Boarduion you might want to look into the possibility of switching it to a 20Mhz crystal for better timing accuracy and resolution.

Mike

[lamb.chop]

Yes Boarduino already built & tested, but will look into this.

By the way I do intend to change the 5v regulator to an automotive grade one to handle any voltage spikes & drops during starting.

[lamb.chop]

From Boarduino website :-

16.00 MHz ceramic resonator is used instead of crystal, so cycle speed may be off by +- 0.3nS (0.5%). This isn't relevant for UART timing, servo drivers, PWM, etc. but could be an issue if you need nanosecond-precision timing. Note that the Arduino software only provides millisecond-precision timing for general sketches (1 second = 1000ms. 1ms = 1,000,000 ns)

So do I need nano second accuracy for ISO communication?

Cheers

Chris

[nickdigger]

arduino provides microseconds

[lamb.chop]

Originally Posted by nickdigger

arduino provides microseconds

I agree, however do I need them?
Is the ISO standard that fast?

[lamb.chop]

Still waiting on LCD from China.
& will replace the oscillator with a crystal to keep the timing / forum happy.

[lamb.chop]

LCD arrived at last & have mounted the freescale OBD ISO interface IC to a DIL adaptor.

[lamb.chop]

Hole cut in case to fit LCD display through.
Having battery drain issues in the MINI so need to sort them out 1st before I install...............