mungo
Part of things
Posts: 318
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Jan 27, 2020 16:24:19 GMT
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I need to fit a rev counter to my old vw bus and I was dreading running a cable all the way through the thing and I thought there must a wireless or bluetooth option these days ....I can't find anything ...I guess in most cases the cable run is not a super big deal like on an old vw bus ....... Anyway, I started to think  ..... I can already connect my phone wirelessly to a cheap OBD2 reader so that part is already done and the phone app's already exist ...what I need to do is convert the dirty old coil neg pulse into OBD2. An Auduino is the obvious choice . Has any one seen it done ? It sounds like a great idea to me (!) to have a little box that connects to to the coil that can send obd2 shiz to your phone. It "could do oil temp ,pressure reasonably easily . Is there a reason no one has done it  This time next year I'll be a millionaire !!!   |
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56' bug 2332 +ida's
56' lowlight ghia
72' bus 1600 devon
67' type 3 square - gone
83' gti - gone
90' gti 16v - gone
82' chevette - gone
70' GP1 Beach buggy -gone
78' lightweight landrover 3L v6 -gone
89' gti - gone
83' gti - gone
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Retro fit OBD2 tacho??Phil H
@philhoward
Club Retro Rides Member 133
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Jan 27, 2020 21:02:33 GMT
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I think you mean CANBUS (which is the transport medium), rather than OBD2? For a comms system like that you need a “master” (an ECU if you like) and then your “slaves” either send info to it, or read from it.
Either way, running a single wire must be easier surely? Only took 20 minutes to do a supply and AV cable for the rear view camera on my 29’ RV..
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gryphon
Club Retro Rides Member
Posts: 330 
Club RR Member Number: 157
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Retro fit OBD2 tacho??gryphon
@gryphon
Club Retro Rides Member 157
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Jan 27, 2020 23:10:29 GMT
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It must have been done... (he says without even googling it) I haven't done this specifically, but I've used arduinos etc to pull info from vehicles CAN networks in the past. You'll need some form of inductive pickup to get the signal from the coil to the arduino. Take it into an interrupt pin and the best way to get an accurate timing is to use a hardware counter to count a clock between pulses - gives you a very accurate RPM each pulse. A less accurate but easier approach is to increment a count each pulse and check and reset that count at a set time interval to get pulses over time. Option 1: CAN wise, A few Arduinos have a CAN peripheral built in which will just need a CAN transceiver (MCP2551 if memory serves). These include the Arduino Due, Teensy 3.2 or 3.6 (££ but my preference), and far cheaper the ESP32 - I've not used that one with CAN though. You can also get an SPI CAN interface board for any other arduino... A super cheap chinese Nano clone will have enough power for what you want. You'll then need the CAN dbc for OBDII signals on the powertrain network - this will give you the message ID and the format of the signals that you need to recreate on the Arduino and push out to the CAN network. Connect the other end to a BT OBDII reader and it will go straight to your phone. Option 2: Skip the CAN altoghether and try to find a specification for the (serial, I believe) data that the ELM237 etc bluetooth devices send out and wire the arduino serial port to an HC-05 bluetooth module and send out the correct signals... As there are many apps that can read it the specification must exist, I've just never looked for it - Might be in here, but I've only had a quick scan: www.elmelectronics.com/wp-content/uploads/2016/07/ELM327DS.pdf
I did a somewhat similar thing for a motorbike a while back - no coil or CAN, but display and logging of engine sensors @10hz.
Word of warning though, vehicles are electronically noisy environments - nothing hobbyist will work as you want it to first time! Learnt that through too much experience!
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Last Edit: Jan 27, 2020 23:12:04 GMT by gryphon
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mungo
Part of things
Posts: 318
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Jan 28, 2020 12:33:48 GMT
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yeah, a wire is way easier ...and I'll probably do that but the easiest way isn't always the most interesting  It stuck me that the fancy split bus guys (who might have a little money and not want to run cables and have gert tach on the dash) might be interested if it worked . I shall report back with any news . Thanks for the info gryphon some good stuff there. |
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56' bug 2332 +ida's
56' lowlight ghia
72' bus 1600 devon
67' type 3 square - gone
83' gti - gone
90' gti 16v - gone
82' chevette - gone
70' GP1 Beach buggy -gone
78' lightweight landrover 3L v6 -gone
89' gti - gone
83' gti - gone
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93fxdl
Posted a lot
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Posts: 2,000
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Jan 29, 2020 22:31:26 GMT
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..... I can already connect my phone wirelessly to a cheap OBD2 reader so that part is already done and the phone app's already exist ...what I need to do is convert 
