Universal Panel Meter

[RobG 1,891]

The MCU is MSP430G2xx3 and the display is Nokia 5110. The project is not finalized, I will add schematic and board later on.

Here are the specs:

Number of channels: 2

Reference: internal or external (space for optional Maxim's, Linear's, and TI's Vrefs.)

Input protection.

Optional shunt resistor.

Host connection: SPI, UART (optional RS232.)

Optional resistor divider and multi turn pot.

Two general use outputs/inputs

Two switches

Board size: 45mm x 45mm (50mm with optional switches and LEDs,) matches 5110 footprint.

 

Little background. My original panel meter was designed to fit behind 4 digit 0.56" LED display. Then I figured it will be better to use 16x2 LCD which will let me display more information. Now, after playing around with 5110, I decided that this display is the perfect choice for me since nothing beats nice GUI.

 

 

[bluehash 1,578]

Does number of channel mean ADC channels?

[RobG 1,891]

The code is still not 100% finished (data logging via RS232 part,) but the UPM is pretty much fully functional.

 

Because I am using headers to plug LCD, the spacers are 0.5".

Normally, LCD would be soldered and the space between LCD and the board would be 0.25".

 

[bluehash 1,578]

Awesome... What font are the numbers?

[RobG 1,891]

I have created my own 10x14 font. It's not the full set, just the numbers, letters, and signs I need.

[zeke 692]

I like this. Good job Rob!

 

Where did you get the LCD from? Sparkfun, iteadstudio or ebay?

[timotet 44]

great work rob

[RobG 1,891]

I like this. Good job Rob!

 

Where did you get the LCD from? Sparkfun, iteadstudio or ebay?

 

That one is from iTead, but I also have some from eBay.

[timotet 44]

Just curious, what is the small row of holes across the bottom of your PCB for?

[RobG 1,891]

The holes make it easier to cut the board. If you don't need LEDs and switches that are in the front (you can mount them on the other side by the way) you can just cut that piece of and make your board exactly 45mm x 45mm, which is the size of 5110.

[timotet 44]

thats what I though they were for

thanks

[username 198]

Nice! I like the display. So voltage only? Is it auto ranging?

 

i'd be sweet if you could do current, connectivity, and ohms. Be pretty sweet to make a msp430 multimeter!

[RobG 1,891]

It can do current (as pictured) using shunt resistor, but no auto-ranging.

[username 198]

It can do current (as pictured) using shunt resistor, but no auto-ranging.

 

sorry, was being blind. Anyhow! Super cool concept and theres still alot you can build off this. I really wanted to make something like this at some point. I only got a 10year old radio shack multimeter so a replacement is needed. Thanks for sharing Any chance you would be willing to share project code for newbsauce like me?

[calin 4]

Nice project ... I like it. I was playing with something similar for a bench power supply I am building.

 

I have one question. While working on my meter I noticed that the ADC on the MSP430 has an habit of influencing the "measured" circuit with its impedance. For example in my case a simple voltage divider that brings 0-20V to 0-3.3V is influenced by the ADC input impedance in quite nasty ways.

 

I do not see anything special in the input channel circuits you have in the schematics that would deal with this issue. Or am I missing something obvious as a novice that I am ?