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PostPosted: Thu Jan 30, 2014 1:48 pm 
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New prototype arrived today, including a re-jigged front panel for the new display and trying white writing on black.

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PostPosted: Thu Apr 17, 2014 9:48 pm 
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hi mate I was just wondering how you were getting on with the obd2 converter. I only ask as I have just bought a converter lead off ebay and was going to try it on my mates reader and see if it reads the signals


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PostPosted: Thu Apr 17, 2014 10:14 pm 
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Have you got a link to the ebay item as I'm not aware of any device currently available to do this.

Sadly little progress since the last post as I've been flat out with work and sorting out duff cars. Aiming to restart 1 or 2 days a week once Easter school hols are over so progress should be fairly rapid.

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PostPosted: Fri Apr 18, 2014 10:12 am 
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http://www.ebay.co.uk/itm/151041875633? ... 1439.l2649

I can send you mine if you think you can do anything with it


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PostPosted: Fri Apr 18, 2014 1:08 pm 
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I'd be interested to know if it works, although i must admit that plug looks wrong going from memory of the diagnostic port.

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PostPosted: Sun Sep 28, 2014 5:01 pm 
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hi nibbles I was wondering if you got any further with this as im still really interested


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PostPosted: Wed Oct 01, 2014 6:09 pm 
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At the moment, no progress since the last update. I'm always flat out with work in the summer, and unfortunately in the spring a couple of other things took up all my spare time between them.
The seasonal rush is now over and I'm currently finishing the other project I was working on at the same time (new design for our electric vehicle controls) then I'll be back onto this. Things should happen fairly quickly once I get going.

The main hurdle / unknown at the moment is getting the SD card slot working including a file system which can be read by a PC directly. Everything else is cracked, just needs software writing / tweaking.

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PostPosted: Wed Oct 01, 2014 6:17 pm 
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p.s. Another slightly relevant device has come to my attention in the meantime. An OBD 1 interface and android software to allow 'logging' of the data direct from the ECU.

http://www.celica-club.co.uk/forum/inde ... n-5-and-6/

It looks quite a useful bit of kit for a low price, but it has 2 major limitations.
1 - it doesn't look like a standard OBD2 device to the software so you're limited to the software provided rather than one of the better known such as torque.
2 - Data rate is low, 1 update per 1.3 seconds so not suitable for quick changing conditions.

I was thinking of producing a low cost obd1 - obd2 adapter which would overcome limitation 1 but sadly nothing can be done about 2.

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PostPosted: Wed Oct 01, 2014 8:19 pm 
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yeah ive spoke to the bloke in Canada who makes them yeah quite cheap otherwise ive downloaded the app he has for it but like you say its limited.
he was ment to get back to me when he has some more ready but nothing yet it just gets hardwired in to the diagnostics post by the look of it


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PostPosted: Thu Oct 02, 2014 4:04 pm 
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Nibbles wrote:
2 - Data rate is low, 1 update per 1.3 seconds so not suitable for quick changing conditions.

I was thinking of producing a low cost obd1 - obd2 adapter which would overcome limitation 1 but sadly nothing can be done about 2.

Limitation 2 can be overcome by interfacing directly with the CPU(s) inside the ECU. Toyota kindly left in the debug USART interface when the S/W was put into ROM. Bascially, every 4ms the CPU sends out a 0xDA byte, if an external microcontroller responds within 20us or so with the RAM address to read, the ECU will reply with the 2 bytes at address and address + 1 in RAM.


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PostPosted: Thu Oct 02, 2014 6:26 pm 
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I have heard of this interface, but does it not affect engine performance if polled constantly ?

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PostPosted: Thu Oct 02, 2014 7:23 pm 
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Nibbles wrote:
I have heard of this interface, but does it not affect engine performance if polled constantly ?

The ECU sends the DA byte and waits for a response whether the interface is used or not. The only overhead is the ECU sending the 2 response bytes back. The USART runs at 1MBaud, so preparing and sending 2 byte response doesn't take more than 30uS or so.

An extra 30uS every 4.096ms is nothing, less than 1% extra CPU load. The important stuff runs at a higher interrupt level anyway.


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