Problem with understanding different electronic circuits

Thread Starter

Randy Le-Bherz

Joined Aug 21, 2015
12
I am at my wits end and about to sell all my Arduino bits and pieces. I recently purchase the 3 items in the attached image. The top 4x7 segment display is what I am having problems with. My display is soldered onto the middle backpack. The bottom image is an Arduino Nano clone.
Can any one advise how to connect my display as it doesn't have the four terminals that the top display has? I have tried it in a breadboard, and selected what I believed were the correct header pins, but nothing worked. Which would be the correct header pins?
The project is a model train speedometer.
How do I test the display to make sure it's working?
 

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MrChips

Joined Oct 2, 2009
21,134
Normally, you are advised to post a link to the device in question. However, I assume you are referring to the Adafruit 4-Digit LED display.

https://www.adafruit.com/product/879

This uses a 4-pin connection because that is all it needs, +5V, GND, CLK, and DAT.
This is I2C interface. You either have to learn how to use I2C or download the libraries provided.

All the information is available on the Adafruit website.
https://learn.adafruit.com/adafruit-led-backpack/0-dot-56-seven-segment-backpack
 

tranzz4md

Joined Apr 10, 2015
310
Ah yes my friend, we all get
"Problem with understanding different electronic circuits"
from time to time.

I'd say Chips has the answer though (once again). Those Arduinos can be just as much fun as model trains, so don't toss those pieces just yet.
 

Thread Starter

Randy Le-Bherz

Joined Aug 21, 2015
12
Normally, you are advised to post a link to the device in question. However, I assume you are referring to the Adafruit 4-Digit LED display.

https://www.adafruit.com/product/879

This uses a 4-pin connection because that is all it needs, +5V, GND, CLK, and DAT.
This is I2C interface. You either have to learn how to use I2C or download the libraries provided.

All the information is available on the Adafruit website.
https://learn.adafruit.com/adafruit-led-backpack/0-dot-56-seven-segment-backpack
Thanks for the reply, Mr Chips. I must not have explained my problem well enough. My backpack, see original photos, doesn't have the 4, easily identifiable terminals. Once the 4x7 displays are soldered on, there is nowhere else that I can identify to connect up to the Nano to run the sketch. Does that explanation make more sense? I cannot determine the terminals to use.
 

LesJones

Joined Jan 8, 2017
2,639
Using a search engine I found this information which seems to cover a range of display modules made by featherwing that use the Holtek HT16K33 I2C to matrix chip. This is a link to the datasheet on the HT16K33 chip which gives the pinout so you can trace which pins on your module connect to the I2C intervace on the chip. The datasheet also seems to give some good information on the I2C interface protocol to help you write the code to interface with the module.

Les.
 

Thread Starter

Randy Le-Bherz

Joined Aug 21, 2015
12
Using a search engine I found this information which seems to cover a range of display modules made by featherwing that use the Holtek HT16K33 I2C to matrix chip. This is a link to the datasheet on the HT16K33 chip which gives the pinout so you can trace which pins on your module connect to the I2C intervace on the chip. The datasheet also seems to give some good information on the I2C interface protocol to help you write the code to interface with the module.

Les.
Thanks Les. I am hopeless at figuring out what to put into google etc. Fingers crossed I can understand the info. Will keep you informed on how I go.
 

Thread Starter

Randy Le-Bherz

Joined Aug 21, 2015
12
Hi! It's me again. This is where I'm getting totally lost.
If you look at the attached pdf, go to page 15. OK all good so far.
P16 all followed. P17 followed up to Run Test! So the sketch is uploaded to the Nano clone.
But! I am unsure how to connect the Nano to the Feather. Which pins on the Nano run the SDA and SCL on the Feather? I believe it's Pins 4&5, but which ones? A4 & A5 or D4 & D5? Do the letters stand for Analogue and Digital?
I cannot find info on this. Thanks again
 

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LesJones

Joined Jan 8, 2017
2,639
I can't help you to find out which pins the "C" software is using for SDA and SCL as I am useless at programming in "C" (I mosly work in assembler.)
The keywords I used to find the information on a search engine came from the picture of your driver board. I first used "HT16K33" and then "featherwing"

Les.
 

spinnaker

Joined Oct 29, 2009
7,835
Hi! It's me again. This is where I'm getting totally lost.
If you look at the attached pdf, go to page 15. OK all good so far.
P16 all followed. P17 followed up to Run Test! So the sketch is uploaded to the Nano clone.
But! I am unsure how to connect the Nano to the Feather. Which pins on the Nano run the SDA and SCL on the Feather? I believe it's Pins 4&5, but which ones? A4 & A5 or D4 & D5? Do the letters stand for Analogue and Digital?
I cannot find info on this. Thanks again

2 minutes of searching

https://www.arduino.cc/en/Reference/Wire

A4 and A5 for the Uno apparently.
 

Thread Starter

Randy Le-Bherz

Joined Aug 21, 2015
12
2 minutes of searching

https://www.arduino.cc/en/Reference/Wire

A4 and A5 for the Uno apparently.
Thanks. I did see this, however I am not confident with what I read. I have sorted most of my problems with this now, except for being able to display the speed. Don't know why. Sometimes it will give me a readout, sometimes it won't. When the unit it plugged in, the 7-segment display goes through its startup and displays 0, which is good. But not matter what I try I cannot get a speed readout consistently. Maybe it's to do with the sensitivity of the opto receivers???
 
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