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'Simple' LCD/Circuit Question

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f0xy

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Hi there,

Ive been hunting round the internet for a few days for a simple solution to how I could solve what I want to do...

I know bits and bobs about electronics, but mainly all I do is join wires and the simple stuff :p

My problem is... I have produced a full loom for a car, well, its pretty small as its just the bare essentials, although I kept a few things in that I was hoping to use, them being: Operating Oil Pressure + Operating Oil Temprature.

Now, these two are single wires, from sensors on the engine block. Ive had a play around with the multi meter, and got some readings of the oil pressure while the engine is in operation... I used the multi meter in 'Ω 200' mode, and the readings showed up like:

5 Bar = -196.0~
4 Bar = -178.0~
3 Bar = -160.0~
2 Bar = -143.0~

All approx values, I wont bother with the oil temprature yet as its pretty much the same readings, and Im just trying to work out how easy this is going to be to do...

What im trying to do is display the current operating oil pressure and temprature on a small LCD display (2x16) that is going to go in a blank space on the clockset. Im just wondering what I need to get this working...

Some sort of LCD controller? Obviously something will need to be programmed? (I have done programming before), So im just wondering if anyone has any ideas of what needs doing for me to be able to display the two pieces of data on a small LCD!

I dont really know much about controllers etc, but I want to learn and get this sorted, as Ive wanted it from day 1!

Thanks if anyone can give any ideas! :)
 
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fOxy, You will probably need to get a micro controller to do the conversion from ohms to a value that can be displayed on a LCD display. Fortunately there are many to chose from. I don't want to get into what one I think is the best for you. You will need to make that choice for yourself. PICs are very well supported in this forum and Nigel has tutorials on the subject. Search in the Micro controller forum. If you noly know basic check out Parallax. They have great support there as well.
 
Thanks for the reply,

Ive just been looking at PICs...Would the reading coming down the wire from the Oil pressure sensor go straight into one of the analouge inputs on the chip, and also, do the outputs on the chip allow direct output to an LCD, or is an LCD controller needed also? Or does an LCD have a controller built in?

Sorry if im being simple, dont really know much when it comes to this yet!
 
fOxy, depending on the micro controller you chose the Oil pressure sensor, I assume is in ohms, would be an input and the LCD can be controlled through parallel output but I would recommend a serial output as it is much easier to code and less wiring. If you are just getting started with micro controllers get a starter platform, learn to upload programs, make LEDs blink on and off, read about Sin, Sout all of fun stuff you can do with them. Who knows this may be just your first of many projects involving micro's.

PS what language did you program in?
 
I don't think you REALLY need a microcontroller, sounds like just a simple LCD panel meter, couple of resistors and a zener diode will do the job. Do you want it to read in Bars like you have listed up there?
 
Yeah, basically im trying to just find out what components I need to purchase, how I need to wire it up/solder it, and then I can program it.... (if im going microcontroller) Im not sure what I need to look for, models of chips, components, etc...It would be so much easier for me to have a list of what to get, and if its easy to connect up, as ive never ever done things like this before....

Because im not sure what I need to put together for it to work, or if this can easily be powered off the cars supply of 12v, dosent need power dropping down or something?

Duffy, yeah, i want to display a range of between say 0 bar and the max it will ever read is 6bar, but also on the same display I want to display the oil temprature, which is similar, just lower values.....
 
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What?

Please tell us how to run a 2X16 LCD display with a couple of resistors and a Zener diode.:confused:

I must be using the wrong ones.:rolleyes:
 
Please tell us how to run a 2X16 LCD display with a couple of resistors and a Zener diode.:confused:

I must be using the wrong ones.:rolleyes:

Mike2545: duffy is referring to LCD panel meter and not simple LCD display :)
I think the resistors and zener diode are for calibration.

f0xy: i agree with Mike2545. I think you should get an LCD 16x2 which displays Pressure in first line of LCD and temperature in the second, Displaying bars on a simple LCD will be very though. You can use a microcontroller which has a built in ADC such as PIC18F4220 or something similar (I find PIC18 easier to code with MPLAB C18 compiler in C language).

Since this controller has one ADC, you might need to poll readings in a loop (for pressure and then for temperature).

a simple pesudocode will be like:

1. Initialize LCD display module
2. Initialize ADC module
3. Write "Pressure: " on First line of LCD
4. Write "Temperature:" on Second line of LCD
5. Read pressure value from ADC
6. Scale it and convert to ASCII characters and display on LCD at particular location (After the string "Pressure:")
7. Read temperature value from ADC
8. Scale it and convert to ASCII characters and display on LCD at particular location (After the string "Temperature:")
9. Goto Step 5 again and so on

As for hardware, you will need a programmer to burn code onto the microcontroller or you can borrow from your friend if this is the only project you are going to do :)
you will need an LCD module 16x2 or 20x2. (where 16 means character in a row and 2 means total rows)
A crystal (oscillator) 4MHz would be enough.
2 non-polar 33pF capacitors
a 10K ohm resistance for /MCLR pin
and a 7805 regulator with maybe a small heatsink.

You can post your progress here and i think a lot of people will help you with the rest :)
 
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for an lcd display you can use a pic to controll it and use a hd44780 controlled display. they can be simple to use and a datasheet is here, a tutorial is **broken link removed**, and a seller is **broken link removed**. i do however advise you to have a look around because you may find a cheaper price.
 
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