Automotive 20x4 chars LCD Display

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  • Hi there,

    I'm working on a small automotive display, using the following stuff:

    • Olimexino STM32 running the latest Espruino 1.65
    • a 20x4 HD44780 LCD 5V (white over blue) for which I'm using external power (and not the 3.3V the Olimexino board provides)
    • a Terratrip speed cable sensor (dedicated racing solution, easy wiring)
    • Simple Voltage Sensors (up to 25VCC, but my truck is 12VCC so it should be fine) to measure various auto probes - these are from
    • and finally a DS18B20 temperature sensor for outside temperature.

    I've picked the Olimexino because it's noise immune, has a more industrial touch and is easily powered by 12V/5V/etc.

    So far I've managed to:

    • flash Espruino 1.65 to the Olimexino STM32 board
    • wire up the LCD and display a mock-up of what I want to achieve
    • run the Date/Time test app
    • build a small app to read voltages using the analog voltage sensors - which I've used to measure every charger and battery in the house - and it works great. I intend to use this to plug to various auto probes but mostly to check the level of battery charging the alternator delivers - in real time.
    • write this post

    I'll try to update as often as I can with code if anyone is interested.

    The information displayed is (left to right, row by row):

    • current speed | current date/time
    • current rpm | exterior temperature
    • partial odometer | engine coolant temp
    • total odometer | battery charging level

    1 Attachment

    • 10404234_636799743083050_1681506668645879971_n.jpg
  • Wow, it looks great!

    How do you measure the RPM - or is that faked for the moment?

  • For the moment everything is faked - but I do have the code working for the voltmeter, time (doh!) and exterior temp.

    I intend to get the RPM from the alternator, which is a somewhat used method. It will involve some trial and error, but no biggie.

  • Ahh, neat idea. If you've got coil on plug ignition you might be able to take a feed off that. On mine it's just a simple 5v signal!

  • Alas, it's a four pot diesel. This isn't the ignition you're looking for... :)

  • you might find this useful:

  • Thank you. That is very interesting, but it's still for gas engines, whereas I run a diesel, hence there is no ignition coil to kick :)

  • You could probably take it off the common rail diesel injectors if you needed to. An opto-isolator would protect it nicely from any back-emf.

    I'd be interested to see how it works with the alternator - would you be trying to measure the fluctuations in voltage coming out of it?

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Automotive 20x4 chars LCD Display

Posted by Avatar for vstef_is @vstef_is