nikojako
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Joined: Fri Feb 09, 2018 11:37 pm

i2c devices not recognized when using breadboard

Mon Feb 19, 2018 5:51 pm

I'm sure my connections are correct. When using a breadboard I

Code: Select all

i2cdetect -y -r 1
I receive a blank i2c address map. When I first tried the circuit it worked fine using a breadboard. At some point it i2c-tools became unable to recognize any i2c device unless I hook that device's data and clock line directly to the RPI3. I verified this issue using kernel 4.14.18-v7+ using Stretch.

I eventually went from i2c based projects to SPI based projects. Could switching from i2c to SPI have caused something to fail?

My problem is a duplicate of this https://raspberrypi.stackexchange.com/q ... i2c-device

I"m using a ribbon cable https://www.amazon.com/gp/product/B074D ... UTF8&psc=1 to connect the GPIO headers to a breadboard. Could parasitic capacitance or inductance be the problem here? If so how would I verify this?

Any help would be appreciated. Thank you.
Last edited by nikojako on Mon Feb 19, 2018 9:03 pm, edited 1 time in total.

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joan
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Re: i2c devices not recognized when using breadboard

Mon Feb 19, 2018 6:52 pm

How long is the ribbon cable? Is it back to front? A photo would help.

nikojako
Posts: 3
Joined: Fri Feb 09, 2018 11:37 pm

Re: i2c devices not recognized when using breadboard

Mon Feb 19, 2018 8:38 pm

*UPDATE*

I've narrowed it down to the ribbon cable, I"ve tried multiple breadboards, and when I plug the ADXL345 into a new breadboard without the ribbon cable, i2cdetect -y -r 1 detects the 0x53 address of the device.

I've verified that I have 3.3 where I'm supposed to. Vcc, CS. I also have it at the data and clk pins.

@joan - the product description is here https://www.amazon.com/gp/product/B074D ... UTF8&psc=1, and states 5.8 x 1.5 x 4 inches but I think they mean the box it comes in. the length of the ribbon cable can't be more than 8 inches from the RPI to breadboard.

Any thoughts, thanks for reaching out.

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FTrevorGowen
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Re: i2c devices not recognized when using breadboard

Tue Feb 20, 2018 7:13 pm

nikojako wrote:
Mon Feb 19, 2018 8:38 pm
*UPDATE*

I've narrowed it down to the ribbon cable, I"ve tried multiple breadboards, and when I plug the ADXL345 into a new breadboard without the ribbon cable, i2cdetect -y -r 1 detects the 0x53 address of the device.
Since you've tried different breadboards, is it possible that one (or more) of them have this pitfall (feature):
viewtopic.php?f=91&t=83372&p=589714#p635787
(Personally, I'm no fan of "plug-in" boards and prefer to solder & triple-check my connections**, but then I've been "soldering-on" for >5 decades ;) )
Trev.
**as can be seen in my webpages.
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my 2xP3A+, P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

nikojako
Posts: 3
Joined: Fri Feb 09, 2018 11:37 pm

Re: i2c devices not recognized when using breadboard

Tue Feb 20, 2018 11:55 pm

@FTrevorGowen- thank you for your reply. I luckily discovered that phenomenon in college. :D

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