Progress update: I have a max ******* setup where I duct taped the circuits and lcd to the right side of the driver's footwell, and drove to work and back today. The setup performed perfectly during both 20 minute trips! I'd say I'm ready to order some more LCDs and build the actual instrument cluster.
Who woulda thought I could make digital gauges into a ******* mod haha? It's coming out of the car tonight. This was a one day only thing, just to make sure it worked before I spent more money on it.
Reseponses in order of who posted first:
@WickedSnake00 (responses to both your posts in here):
There is hardware out there to read PIDs and whatnot. From what I can tell, there are 3 potential options: 1) ELM327 2) SNT1110 3) Half assed **** from china. It seems everything is derived from one of those three.
The SNT1110 is newer, has updatable firmware, is faster, and is less than 1/3 the price of the ELM327 ($10 vs $32). There is really no reason to get the ELM327 instead of the STN1110. I guess the only reason to go with the ELM327 is that they have better documentation of the commands. The STN1110 accepts every command for the ELM327, so the STN1110 documentation literally tells you to go look at the ELM327 documentation lol.
Please refer to the “AT Commands” section of the ELM327 datasheet for
the complete description of the AT command set.
DO get either one of those chips over the china garbage. They claim they are ELM327 chips, but they are really a different chip with cracked ELM327 firmware, and supposedly most of them dont work right. Basically everything you see on ebay is chinashit.
The ELM327 and the STN1110 both have circuit diagrams in the datasheets, so you just order the main chip and get all the other parts from somewhere like digikey (cost me about $15 for all these other components) and put it all together. The only issue is the surface mount chips, and the fact that 2 of the transistors are discontinued from the STN1110 datasheet. I guess I might as well put it here, transistor 3640 only exists as MMBT3640, which is a tiny surface mount. Transistor 3646 is discontinued and has no official replacement. I found that some guys fixing ancient casio calculators were using a 2N4401 instead, so thats what I used and it works fine. To deal with surface mount chips, you can buy a completely copper coated circuit board from radioshack, draw where you want the copper paths to be on the board with a sharpie, and throw it in a bucket of hydrochloric acid + hydrogen peroxide. The acid will eat all the exposed copper and the sharpie will protect the copper that you want to keep. You can then solder the surface mount chip to the copper traces you created, and then solder wires to the other ends of the traces.
The arduino is programmed via USB. It has its own free software where you can write the code, upload it to the arduino, and test the serial connection (which is how it talks to the STN1110/ELM327/chinashit). I programmed it with my desktop, tested the code with the software's built in serial monitor until everything worked as expected, then stuck it in the car to test it. After some minor tweaks and the realization that I needed to turn echo off for the STN1110 (the command for that is AT E0), everything worked without too much fuss. The arduino saves the last program uploaded to it and runs it automatically as soon as it gets power, so if you program everything the way you want it, you never have to take it out of the car again. As far as car troubleshooting, you dont even need the arduino. You could just disconnect the arduino from the STN1110/ELM327 and connect your computer to the STN1110/ELM327 instead. You would probably need a serial-to-usb adapter unless you have an old ass laptop. If you get that hooked up, you can send commands straight to the car using a terminal emulator program (I seem to recall reading Hyperterm as an example). You could pull error codes, check coolant temperature, see if the engine is running in open/closed loop or limp-home mode, reset the check engine light, and I think you can get all the engine parameters at the exact moment the check engine light came on (the computer saves this data until the next time the light comes on). Basically, if the computer has it, this chip can read it (provided you know how to request the data!).
As for modes, I think most (maybe all?) Fords use the J1850 PWM protocol. I only built my STN1110 circuit to work with J1850 PWM because thats what our cars use. The website for the STN1110 says that it works with J1939 too (and nearly every other protocol for that matter). About the only thing I heard it doesnt work with is some of the semi trucks.
@everyone with compliments:
Thanks! I'm probably not as smart as you think. I have absolutely no prior experience with PIDs or programmable microcontrollers (the arduino). I have released the magic blue smoke from more circuit components than I care to admit haha :dunce:. I just started reading about all this stuff a month or so ago. All it takes is motivation. So to help you all along, I will be going around and hitting everyone's gauge cluster with a hammer :banana
@laoutlaw01:
Don't worry, it is impossible to offend me. Give me your best shot!
I'm not gonna lie, I was a bit ashamed having to ask how to post pics lol. In my defense, I saw this attachment button that is supposed to let me upload a pic directly to the moddedmustangs website. I tried everything (resizing the picture to make the filesize smaller, resizing it to make the dimensions smaller, resizing it to be really really tiny, etc...) but it just wouldn't upload. I don't know why I didnt think of photobucket. Probably because I didnt have an account. But still, thats sad on my part haha. Also, with regards to me being smart, thank you.
@cschoening09:
I will try to record and post a video of the experimental HUD setup to youtube. I would take a pic, but it just looks like an image reflecting off a piece of acrylic. Not very exciting to see a pic lol. I actually have the image somewhat collimated, so the image appears to be far away. That way your eyes dont have to shift focus from the road (far) to the uncollimated image (near) and back.
@StockD15b:
Yes, this is exactly like a scangauge but better! A scangauge has only 1 lcd to display stuff on. The arduino could have....40 some? I dont wanna count all the pins on the arduino lol. Anyway, I can connect A LOT of lcds and show all kinds of info. I can also read error codes and reset the check engine light with this (scangauge cant). I can also program the arduino to use all the different values the computer gives us to calculate stuff, like instant MPG, average MPG, instant fuel consumption, etc. Also, since the arduino can be connected to a bunch of other cool things, a smart person could for example attach an accelerometer, a gps chip, and a flash memory card to datalog engine parameters, speed, mpg, cornering/acceleration/braking forces, and gps location, and then put all that info onto a map of a city or racetrack or whatever. I'm not smart enough to do that so don't get your hopes up lol. I'm just saying, it is technically possible.
@everyone:
I'm not sure if anyone really cares for an explanation, but if you want I can try to explain what all is going on in extremely simple terms. The basics are (surprisingly) not very complex.