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I use the ELM chips quite often for OBDII applications, there are no similar chips that I know of, and I looked for quite some time before I found ELM.There is one with similar functions(harris or harrison I think), but it's triple the price.The ELM's are just Microchip PIC's with ELM's code, you could write your own code and just program a PIC.
Nah, after thinking about it, it may not be worth all of the effort. Although, this may be some good competition for the ELM chips. This'll probably be a project on down the road a bit, once I get familiar with using microcontrollers on a better level.
Hold on a second here. :shock: I have been looking through the datasheets for these ELM3xx IC's, and they state that they are using Microchip's PIC 16C5xx, PIC 16c505 etc. These microcontrollers are listed as less than $2.00 on the Microchip website!!! If we put some programming time in, we can give these ELM chips a run for their money! $10 vs $2, hmmmm.
It's a question of whether the time is worth the extra $10-$15, If your vehicle is ISO-9141(which is the easiest of the OBDII protocols), it would be a close call, american SAE J1850 would not be worth the effort.Not to mention, papers containing exact details of the protocols are only available from SAE or ISO, and they cost $80+.