How could I implement a digital speedometer like this into my car? The light went out on my old volvo 850 spedometer which caught my interest in modding it.
>>917228
the later p80 v70s had a signal wire that gave you the speed for things lke changing the radio volume that you could have used but that was with the ETM, i don't know what an old 850 with a traditional throttle is like.
but essentially you figure out how the speed is communicated to the dash on the physical and data layers and build a system to analyse and display the result.
pretty much any microcontroller could do this with perhaps some additional circuitry to convert voltage levels to something suitable.
couple of shift registers and a handful of leds to display the output. possibly some hysteresis in the micro code because the last thing you want is lights flashing at you distracting your attention when you drive.
>>917228
inb4 OP gets arrested for making that and later gets to meet Obama
Can't you just use a phone + digital speedometer app (with gps) to make do?
Many motorcyclists use digital bicycle speedometers.
>>917228
That pic just reminds me how shit yur a poor cars are compared to American. They're so much slower they made up a system so that they both can hit 70 on the speedo, even though the shit box is going much slower
>>917424
what kind of retarded are you?
>>917228
I've got a 745 which runs by wire, yours might be the same, otherwise look up some forums or manuals. In the 745 the wire sends a pulse every rotation iirc.
>>917231
>>917541
Don't know about this car but it doesn't sound hard if this already exists. take that signal use it to trigger an opto-isolator for a mcu pin, in mcu 1 pulse=1 rot, measure number of rotations in a min = rev/min, (like taking a pulse), so you gonna need to know some angular rotation math convert to angular speed then linear, or find some equation that someone already made.
i'd output to an LCD first, since these things are easier to use in proto, an analog looking face might require some mo' math and time and material cost
You'll need a OBD2 bluetooth module for your car and a HC-07 Bluetooth module for Arduino. These two items shouldn't cost more then 10$.
There are tons of examples online
>>917537
Not a retarded, I actually bought a car that goes 70
>>917228
>>917569
This
The ODB port is basicly a direct connection to the ECU (Engine Control Unit) that gives you a lot of information (specifics depending on car). Just figure out how to interface with that, and you get ALL the data, probably even down to engine timings.
Also, ofter this port allows a fair bit of control of the vehicle operations as i understand. IDK what you can do or even if it is protected, but just FYI i think you can make a self-driving car with this
>>917621
basic obd2 is emissions only, but like fucking kitchen sink emissions, like its not just oh too much co or anything, its like oh cylinder knock which could let unburnt fuel into the cat and increase emissions
so you do get rpm but i don't know if you get ground speed because how does it know what gear you are in?
new cars will have canbus which is probably in the same obd2 port but its not really obd2 is it? i dont know probably some kind of pedantry available here.
but its up to the manufacturer if they put canbus control for your fly by wire throttle/brake/steering assist.
odb2 engine data for emissions is manditory
>>917628
See https://theksmith.com/software/hack-vehicle-bus-cheap-easy-part-1/
It can't be that non-standard, or there'd be no point to all those off-the-shelf OBD2 speedometers.
>>917628
the CAN bus is designed for multiple peripherals being linked togeather. Never really looked at it, but might do so soon. FIRST has moved to CAN btw.
from the official site
http://obdii.com/background.html
[code]
On-Board Diagnostic systems are in most cars and light trucks on the road today. During the '70s and early 1980's manufacturers started using electronic means to control engine functions and diagnose engine problems. This was primarily to meet EPA emission standards. Through the years on-board diagnostic systems have become more sophisticated. OBD-II, a new standard introduced in the mid-'90s, provides almost complete engine control and also monitors parts of the chassis, body and accessory devices, as well as the diagnostic control network of the car.
[/code]
>>917652
>>917628
It appears that this is directly connected to the CAN bus, and so yes, you probably get FULL control of the car through this.
>just speculating
PINOUT
Pin 2 - J1850 Bus+
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line
Pin 16 - Battery Power
>>917231
this
>>917228
trans-speed sensor is most likely a reluctance pickup. if so the voltage generated will increase as you accelerate. and you'll need to a ac to dc converter. try to use the original maybe?
if its a hall-effect pick then youre in luck
do sensor straight into microprocessor since hall-effect on cars never exceeds 5v
>>917604
>Not a retarded
I beg to differ.
Polite sage for lack of content.
>>918046
is that really you Heaven!?
