7-segment display wiring? HELP?

Discussion of the physical aspects
Perpetualbrews
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7-segment display wiring? HELP?

Post by Perpetualbrews »

Hello,

I just purchased 4 7-segment displays. Followed the instructions i found on the forums. Can anybody explain the wiring protocol? I know that there are two wires that go to exp 0 and exp 1, we wired 12v power to the little plug above the connector, and from previous pictures we saw there was a ground going from the display to the BCS unit? where is this wire on the new display units from brewers hardware? Also, people i keep reading to ground the bcs to the display and also to the 12v power supply. our power 12v power supply only has two wires?

thanks for the help! we are a bit lost!

also, the units turn on when given power, cycle through, then display nothing.
JonW
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Re: 7-segment display wiring? HELP?

Post by JonW »

The communication protocol is called "I2C" (eye two see). That is the exp0 and exp1 wires from the BCS.

When using externally powered devices that share a communication link like this, you must tie their grounds together. You can do this by running a jumper from the display negative power terminal to the BCS negative terminal. This gives both devices the same earth ground reference.

Additionally, make sure you have them enabled in the BCS config.
Perpetualbrews
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Re: 7-segment display wiring? HELP?

Post by Perpetualbrews »

Thanks for the quick response. Forum NOOB. Trying to figure out how to upload a pic to make this easier.

4 displays are enabled and running 4.0

I have 2 wires coming from 12v power supply running board.

My i2C cables from SCL and SDA are going into EXP0 and EXP1.

I have two remaining wires on i2c cable that are loose. One says GND and the other is 12v power.

1) So i should ignore the loose two wires? I tried running the GND from i2c plug to BCS unit GND and did not help.
2) You recommended connecting display negative terminal to BCS negative terminal. So i am jumping the negative terminal from 12v supply for display and running that to where on the BCS unit? I currently have an outlet box inside my housing with a wall wart to my bcs unit.

Hope this makes sense. thanks in advance
JonW
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Re: 7-segment display wiring? HELP?

Post by JonW »

Perpetualbrews wrote: 1) So i should ignore the loose two wires? I tried running the GND from i2c plug to BCS unit GND and did not help.
The LCD displays can be powered from either the 12V terminals or the two remaining wires on the 4 pin plug. I power mine on the 4 pin plug.
Perpetualbrews wrote: 2) You recommended connecting display negative terminal to BCS negative terminal. So i am jumping the negative terminal from 12v supply for display and running that to where on the BCS unit? I currently have an outlet box inside my housing with a wall wart to my bcs unit.
You run the 12V negative wire to the BCS negative wire (GND) on the BCS terminals.
Perpetualbrews
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Re: 7-segment display wiring? HELP?

Post by Perpetualbrews »

I am no electrician bit explain to me why I would connect the negative 12v wire to the ground on the bcs unit? I am afraid this would fry something on the bcs unit.
JonW
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Re: 7-segment display wiring? HELP?

Post by JonW »

Voltage measurement is the difference in voltage potential. To get a proper voltage, you need a reference point. That reference point is the ground. In cases like the LED's where you have a 12 volt device being controlled by a 5 volt device, you need to ensure you have the same voltage reference point - thus the reason to tie their negative (ground) lines together. Without this, you can cause a ground loop that can affect the operation of one or both units. This could even be affecting your temp fluctuations because the 12V device can be seeking a ground potential through the I2C connection of the BCS. Ground them together and place a jumper to an actual earth ground.
drbenj1
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Re: 7-segment display wiring? HELP?

Post by drbenj1 »

To the OP, did you ever figure out what the problem was. I am having the same issue. Displays power up and cycle through and then display nothing. I have checked the wiring a hundred times and everything seems correct. 12v to power supply, ground to ground which is connected to BCS ground, 12v - and 120V AC ground. The other two wires are hooked up to the EXP0 and EXP1. Any help would be appreciated.
kwhizr
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Re: 7-segment display wiring? HELP?

Post by kwhizr »

Bump - any update?
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oakbarn
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Re: 7-segment display wiring? HELP?

Post by oakbarn »

I have the same issue.
JonW
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Re: 7-segment display wiring? HELP?

Post by JonW »

I really have no answer for you guys.... My fear is that some mis-wiring has fried either the BCS I2C circuit or the display I2C circuit.

If someone wants to ship both their BCS and displays in, I can troubleshoot and figure out what the problem is.
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