i2c bus error with LED marix on RasPi

This is mostly for myself but I figured I would post it here as well. After putting together and setting up my new 8×8 bi-color LED matrix and i2c control PCB from Adafruit, I got a script error saying “Error accessing 0x70: Check your I2C address”. When I run sudo i2cdetect -y 0, I get nothing, but the matrix is detected when I run sudo i2cdetect -y 1.

So apparently the original version ran i2c on #0, but now it is on #1. So the test scripts are looking on the wrong bus for the device. Making a change to Adafruit_I2C.py to reflect the proper device bus should fix the issue… I guess I will find out tonight.

Original post text:

Mini 8×8 w/ Pi not working

Postby jamestenglish » 19 Dec 2012 01:19

I am trying to get the mini 8×8 LED with backpack working with my Raspberry Pi, but I keep getting the error:
Error accessing 0x70: Check your I2C addressI am using the Occidentals 0.2 linux build.

Below are pictures of the Soldering, wiring, and console output. If there is any other information I can provide just let me know

Soldering:
Image
Image
Image
Image

jamestenglish
 
Posts: 2
Joined: 19 Dec 2012 01:10

Re: Mini 8×8 w/ Pi not working

Postby adafruit » 20 Dec 2012 21:36

can you check if its using i2c bus #0 or #1? it should be #0, try hard-coding it in the python script!
User avatar
adafruit
 
Posts: 10182
Joined: 06 Apr 2006 20:21
Location: nyc

Re: Mini 8×8 w/ Pi not working

Postby jamestenglish » 22 Dec 2012 16:17

I hard coded it in the python script and it seems to work now, thanks!
jamestenglish
 
Posts: 2
Joined: 19 Dec 2012 01:10

Re: Mini 8×8 w/ Pi not working

Postby nkane3 » 18 Jan 2013 20:01

I am have the same exact problem. Except I have a RPi Rev 2. When I run sudo i2cdetect -y 1 it reads 70 and sudo i2c detect -y 0 is reads nothing. When I run the test code (ex_8x8_pixels.py), I get the same exact problem: Error Accessing 0x70: Check your I2Caddress. Im not sure how to hard code it in python. And for my board, should I be using #1? How would I change this?
nkane3
 
Posts: 2
Joined: 11 Jan 2013 23:18

Re: Mini 8×8 w/ Pi not working

Postby nkane3 » 18 Jan 2013 22:07

Nevermind I figured it out. For those with the same question, the Revision 2 does use I2C #1. In order to hard code this, go into Adafruit_I2C.py and uncomment one of the two lines. The lines will say which raspberry pi they correspond to.
nkane3
 
Posts: 2
Joined: 11 Jan 2013 23:18

Re: Mini 8×8 w/ Pi not working

Postby Awright754 » 19 Jan 2013 15:08

I have a very similar issue with my 7-Segment display, i run the example script ‘ex_7segment_clock.py’ and get ‘Error accessing 0x70: Check your I2C address.
The device shows up on i2cdetect as 0x70. I found the line in the scrpit ‘Adafruit_I2C.py’ that i need to make active so i can get my Pi model (I have model B), however i cannot edite the file as its states ‘Errno 13 permission denied’ when i go to save the file.
Anyone any ideas what i can do?
Awright754
 
Posts: 2
Joined: 19 Jan 2013 15:03

Re: Mini 8×8 w/ Pi not working

Postby Awright754 » 19 Jan 2013 15:28

Got it, just moved all the files i needed into a new folder!
Awright754
 
Posts: 2
Joined: 19 Jan 2013 15:03
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s