LED display

Forum 2005-2010 (read only) Hardware Interfacing
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Hi there,

I have a led panel meter, i noticed that panel meters available
at sparkfun take about 7pins, i found a panel meter which
has a IC in the circuit to control how the numbers get split up i think,
so it only has 1 input, and ground.

Im currently taking temp and humility readings every 500 milliseconds. With other led displays i see they setup a pin for every segment, its not necesarry with my led display, how would i go about printing to this hardware ? I just takes a voltage reading and displays it so i cant be that difficult, can it? 1 input ?

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anybody ?

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You are not very spcific on what you have, you say:-

so it only has 1 input, and ground.

So no power then?

Only 1 input suggests a serial input which begs the question is it TTL voltage levels and what is the baud rate and data format? You need the data sheet on your device before any of these questions can be answers.

Good as we are we can't discover what device you have by mind reading, and breaking an entering never was my fortay, even if I knew where you lived. :wink:

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haha okay i see what you mean, im real new to this, my panel meter has 4 inputs then, its a kit i assembled(it works)

panel meter specs:

  • supply input 5VDC, single supply operation
  • maximum range, 0-199mV
  • Berg connector for connecting supply input and signal in
  • decimal point position is selectable via jumper

The chip on the panel meter PCB seems to be a 7107 ic.

boad rate from arduino is 9600, im taking readings from sparkfuns SHT15 humidity/temp breakout board.

My script runs returns values in Bytes which is converted to RH && temp into degc which currently prints to my serial port, so i know its all working.

I just dont know how to print to this decide.

Any help would be appreciated.

Charl.

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7107 ic.

Google suggests it's a simple 4 digit voltmeter.
What were you thinking of doing with it?

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If it is a true LED panel meter then the one input is an analogue voltage input. You have to feed an analogue voltage into it (range? resolution?). Built inside it is an analogue to digital converter and a display driver there is no access to the digits it produces. Therefore you will not be able to feed a number into it. The closest you could get is to generate an analogue output from the PWM output. This would need smoothing with an RC filter first. However, the PWM output only has 8 bit resolution so that means you can only produce an output voltage in steps of 5 / 256 = 0.01953125V steps. Therefore it is unlikely that you would be able to track the number you put to the display and any number you sent out of the serial port.

Basically I don't think you can do what you want with what you have.

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The meter you have is looking for an analog voltage 0-0.2v. I suppose you could use the PWM feature on the Arduino along with a voltage divider and filter and drive it with that. If you don't understand what I just said, better look for another avenue.

If you want a simple serial display and sample code to boot, try
http://cgi.ebay.com/Epson-serial-VFD-Display-Arduino-LCD_W0QQitemZ110427341155QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item19b5fb8163&_trksid=p3286.c0.m14

You can also go with an LCD display, it will involve more wiring but you will also find plenty of examples to get you moving along.

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