Brightness Problem - 7-Segment LED Backpack with the Raspber

[krakow2]

Hi all.
I bought a Adafruit 1.2" 4-Digit 7-Segment Display w/I2C Backpack that I successfully connected to my breadboard and Raspberry Pi following the these instructions http://learn.adafruit.com/matrix-7-segm ... i?view=all

All is working fine except one thing. The display is very dim. I can barely see whats on the display in daylight. Funny thing is that the decimal points shines very bright. Only the digits are dim.

Does anyone have an idea where to start to look for the problem? I have gone through my soldering, which looks fine and I'm pretty sure that I have everything connected right.

I have tried to search this board and google without finding a solution or anyone else with the same problem. Thanks in advance.

[adafruit_support_rick]

The tutorial has this suggestion:

If you want them a little brighter, connect the VCC pin of the backpack to 5V. There are 10K pullups on the backpack to 5V. As long as the backpack is the only i2c device on the i2c bus with pullups to 5V this is perfectly safe for the Pi. If you have 2 or more 5V i2c devices, the 5V pullups may 'overpower' the Pi's strong 3.3v pullups, in this case you'll want to use a proper level shifter: https://www.adafruit.com/products/757

[krakow2]

Thank you but I don't think that is the problem or the solution.

The thing is that some of the leds are very bright; that is the colon-dots. If all leds were dim I would not suspect I did something wrong. Is it normal that there is different brightness on different leds?

The tutorial has this suggestion:

If you want them a little brighter, connect the VCC pin of the backpack to 5V. There are 10K pullups on the backpack to 5V. As long as the backpack is the only i2c device on the i2c bus with pullups to 5V this is perfectly safe for the Pi. If you have 2 or more 5V i2c devices, the 5V pullups may 'overpower' the Pi's strong 3.3v pullups, in this case you'll want to use a proper level shifter: https://www.adafruit.com/products/757

[adafruit_support_rick]

Without seeing the situation it's difficult to tell. However, the dots are smaller - they may require less power to light brightly. Can you at least try running it on 5V and see if it makes a difference?

[krakow2]

Without seeing the situation it's difficult to tell. However, the dots are smaller - they may require less power to light brightly. Can you at least try running it on 5V and see if it makes a difference?

That actually did help. All leds are now bright and, as far as I can see, has the same brightness. Thank you.

But now I got another problem I need to figure out how to solve. I got the following error message printed in the console:

Code: Select all

Error accessing 0x70: Check your I2C address 

and after a while the clock-script I'm running (ex_7segment_clock.py) is behaving strange. I get some irregular strange chars and numbers after the script has been running a while. Diods are lightning up without any logic.


This is harder than I thought to get running

[adafruit_support_rick]

That is likely to be a connection problem. Are you using long jumper wires? Maybe try some different jumpers, different breadboard sockets, etc. Post some pictures and we'll check your soldering

[jasper9]

How should the logic level converter be wired? I'm guessing:

Rpi & Level Shifter
3v to LV
5v to HV
ground to both GND

Connect both SCL and SDA to each A1/A2 and B1/B2 to the displays? Or only one of them?

Sorry new to these guys. Thanks!!

[adafruit_support_rick]

You have multiple displays?
I2C is a bus. You can connect B1/B2 to one of the displays, and then connect to the next display from there.
Or you can fan out to all of your displays from B1/B2. Either way should work.

[jasper9]

Pronouns! Sorry, when I said "them" i meant SCL and SDA (not multiple displays). But yes I do have multiple displays. Do I have that right, connect SCL to A1, SDA to A2, and the displays to the corresponding B side?

[adafruit_support_rick]

Yes, that's right.