USB and RS232

Hugh

I have a Prop-based box that used to drive an ELM327-based OBD reader, logging engine parameters of my car, etc.. This used FullDuplexSerial to drive an RS232 connection and everything was fine until I broke the ELM327 OBD unit - all possible replacements have a USB connector for connection to a laptop. (Progress, eh?!)

If I were feeling brave, is there any way that I could connect the USB connector from the OBD box into a prop-plug and achieve a connection that way or is there a fundamental flaw in this plan (such as power coming from the USB plug)?

If not, any other ideas please?

Thanks,

Hugh

MagIO2

No way with the prop-plug. The OBD is a slave device. It needs to be attached to a master device. The prop-plug is also a slave.

I don't know how skilled you are. I'd guess that most OBD devices also use a USB 2 serial converter. So, if you open the box it could be possible to identify the chip and find the serial connection to the OBD controller. Here you could connect the propeller after some small PCB modifications ;o)

Hugh

MagIO2 wrote: »

I don't know how skilled you are. I'd guess that most OBD devices also use a USB 2 serial converter. So, if you open the box it could be possible to identify the chip and find the serial connection to the OBD controller. Here you could connect the propeller after some small PCB modifications ;o)

That was my cunning plan. Having bought a couple of ELM327 devices on eBay they both turned out to be PIC-based clones. I may soon know how completely they have been cloned (an abhorrent abuse of intellectual property).

MagIO2

Ah ... PIC ... some PICs have an USB port, so they don't need an USB 2 serial converter. This would be bad luck for you.

DynamoBen

If you use a real ELM327 you can bypass all the RS232/USB circuitry and tie directly to the TTL pins, which is what I do. (18=Rx, 17=Tx) If you go the clone route, you are on your own.