General > General Technical Chat
ODB II vehicle diagnostics circuits?
ToBeFrank:
--- Quote from: awh4992 on January 20, 2012, 06:35:04 pm ---So I realize this thread is a little on the old side, but if anyone is still interested in the "make your own" OBDII reader and such, I have an open-source hardware design available that is a OBDII to Bluetooth adapter based on Scantool.net's STN1110. Altium sources, PCBs, and even assembled units are available for those that want them. Schematics are also in PDF format for those that don't have an Altium viewer.
Here's where my open-source adapter lives: http://batman.homelinux.com/blog/bluetooth-obdii-adapter/
--- End quote ---
It looks like only the OBD chip adapter design is open source? I don't see a pdf for the bluetooth part, which I assume also has the power supply circuit. And why open source a design that requires a $5000 piece of software to modify it? Sorry, that always annoys me.
awh4992:
--- Quote from: ToBeFrank on January 20, 2012, 08:21:51 pm ---
It looks like only the OBD chip adapter design is open source? I don't see a pdf for the bluetooth part, which I assume also has the power supply circuit. And why open source a design that requires a $5000 piece of software to modify it? Sorry, that always annoys me.
--- End quote ---
So you want a PDF for the RN-42? Use google, there's no point in me hosting the datasheet for Roving Network's product, as it could easily become outdated. The RN-42 only does one thing: translate back and forth the UART data going to/from the STN1110 chip.
If you actually looked at the schematics for the design, you'd see the power supplies to generate 5V, 3.3V, and 8.5V.
So...you want the RN-42 (the Bluetooth module) open sourced, which while you're correct in saying that it requires loads of $$$ in licensing, it also requires a lot of money invested in RF design and in wireless certifications not to mention the software development involved. FCC and CE certifications aren't free and a simply paying their fees and bringing them a device to be certified doesn't guarantee you'll get the certification. You'd also need to know how the CSR BC4 chip onboard interacts w/ the rest of the stuff on their unit to be able to change the software...etc.
Oh yeah, and the STN1110. That's obviously not open source either. Sure, someone could write the tons of code required to emulate the ELM327, test it to make sure it complies w/ all the vehicle protocols and buy all the SAE/ISO/whatever standards to make sure you're correctly implementing communications w/ those standards?
All I'm saying is my adapter is open-source hardware. The stuff I've designed is there for others to see and use if they'd like. When you find a open-source hardware and software Bluetooth serial module (oh ya, that has FCC and CE certifications too) and a open-source ELM327 compatible part, let me know and I'd be more than happy to use them.
ToBeFrank:
--- Quote ---If you actually looked at the schematics for the design, you'd see the power supplies to generate 5V, 3.3V, and 8.5V.
--- End quote ---
I looked at your PDF schematic files since I don't have Altium. There are no power supply circuits in there.
awh4992:
--- Quote ---If you actually looked at the schematics for the design, you'd see the power supplies to generate 5V, 3.3V, and 8.5V.
--- End quote ---
I looked at your PDF schematic files since I don't have Altium. There are no power supply circuits in there.
[/quote]
Ooh I think I know what's going on. You're probably not looking at the schematics for the correct board where the power supplies are located. As stated on my blog right above where you can download the designs, two PCBs are needed to make a complete module, a bluetooth board and a driver board. Since there are 2 boards, there are also 2 schematics. Look at the schematics for the STN1110 Universal Driver Board (http://batman.homelinux.com/blog/obdii/STN1110_Driver_Board_R3.zip). In those schematics, you'll see the power supplies and all the driver circuitry for interfacing the STN1110 to the vehicle. The RN-42 schematic only shows the connections between the STN1110 and the RN-42. The 2 boards make a stack as shown in this pic (BTM-182 BT module here): http://batman.homelinux.com/blog/wp-content/uploads/2011/09/STN1110_top.jpg Sorry for the confusion.
The intent w/ the 2 boards is that the driver board can be used w/ any of my Bluetooth boards that has a STN1110 chip on it (I think I have 3 different Bluetooth boards, although the only Bluetooth module you can get now is likely the RN-42). Likewise w/ my ELM327 designs, there' s a driver board that's common amongst all the ELM327 Bluetooth boards.
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