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ByteYourLife
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7" touchscreen I2C address problem

Tue Jul 11, 2017 6:05 pm

Hello,
I bought one of the official Raspberry Pi touchscreens and connected it my Raspberry Pi 3 Model B.
I installed the latest Raspbian OS und updated the OS.

The I2C wires (SDA SCL) are connected as well the 5V and GND wires. Nothing else is connected to the I2C bus.

But if I execute the command "sudo i2cdetect -y 1" I get many different I2C address displayed which are jumping and changing.
The result from "sudo i2cdetect -y 1" looks like the picture below:

Image

This is the output from the picture:

Code: Select all

pi@robi:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 -- -- 29 2a 2b 2c 2d 2e 2f
30: 30 31 32 33 34 35 36 37 -- -- 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c -- -- 5f
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 -- -- 74 75 76 77
pi@robi:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          03 04 05 06 07 08 09 0a 0b 0c 0d -- --
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 72 -- -- 75 76 77
pi@robi:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a -- -- 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 -- -- 48 49 4a 4b 4c 4d 4e 4f
50: 50 51 52 53 54 55 56 57 58 -- -- 5b 5c 5d 5e 5f
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 72 73 74 75 76 77
pi@robi:~ $
Does any one has seen the same problem and know how to fix it or what the problem is?

Any help is highly appreciated.

ByteYourLife
My project I am working on: An autonomous driving car with the Raspberry Pi and a lot of sensors.

6by9
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Re: 7" touchscreen I2C address problem

Tue Jul 11, 2017 7:14 pm

Disconnect the i2c wires. They are only needed on Pi 1 models a and B. All other models have i2c already wired up the flexi cable.
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ByteYourLife
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Location: Germany
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Re: 7" touchscreen I2C address problem

Tue Jul 11, 2017 8:26 pm

Thank you very much 6by9 for your fast help.
You are right now everything is working fine.
Thank you very much!
My project I am working on: An autonomous driving car with the Raspberry Pi and a lot of sensors.

tony359
Posts: 59
Joined: Mon Dec 21, 2015 9:59 pm
Location: Swindon, UK

Re: 7" touchscreen I2C address problem

Sun Jan 05, 2020 12:10 pm

6by9 wrote:
Tue Jul 11, 2017 7:14 pm
Disconnect the i2c wires. They are only needed on Pi 1 models a and B. All other models have i2c already wired up the flexi cable.
THANK YOU 6by9

I'm appalled that this critical information is nowhere to find in all the tutorial I found on the network on how to wire the touchscreen!!!

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davidcoton
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Re: 7" touchscreen I2C address problem

Sun Jan 05, 2020 12:16 pm

tony359 wrote:
Sun Jan 05, 2020 12:10 pm
I'm appalled that this critical information is nowhere to find in all the tutorial I found on the network on how to wire the touchscreen!!!
Whose tutorial (link)?
If its by RPF, it can be reported and corrected.
If a third party, caveat emptor!
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6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 10576
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Re: 7" touchscreen I2C address problem

Sun Jan 05, 2020 2:26 pm

The official docs are https://www.raspberrypi.org/documentati ... /README.md
The information on the I2C wires appears to have been hidden slightly now, but it's at https://www.raspberrypi.org/documentati ... /legacy.md
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

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