10dof imu and pull-up resistors

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countzero
 
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10dof imu and pull-up resistors

Post by countzero »

Hi there,

I'm trying to get the Adafruit 10dof imu to play nicely with another i2c sensor on my arduino uno 5v. The other sensor is a maxbotix i2c unit, which recommends a 4.7k pull up resistor in both SDA and SCL. Individually, the 10dof and the maxbotix sensor work just fine, without any pull-ups. But when I put them together, they don't work. If I put in 4.7k resistors, will it affect the reading, performance or life of the 10dof in anyway? Want to make sure of this before I end up frying anything.

Thanks.

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adafruit_support_bill
 
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Re: 10dof imu and pull-up resistors

Post by adafruit_support_bill »

The 10DOF unit has pullups on-board. You only need one set of pullups on the bus. Although extra pullups (within limits) should not cause problems.

What you describe sounds like it might be an address issue. Make sure that the two devices do not have conflicting i2c addresses.

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countzero
 
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Re: 10dof imu and pull-up resistors

Post by countzero »

From adafruit documentation, 10dof uses I2C 7-bit addresses 0x19 & 0x1E & 0x6B & 0x77
Maxbotix i2c default address is 0x70. So from what I see, no conflict there...

Is there anything else I can try?

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Re: 10dof imu and pull-up resistors

Post by adafruit_support_bill »

If you post photos showing your wiring we can look for anything suspicious. If you have access to an oscilloscope, we could check that the bus-signals look OK.

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Re: 10dof imu and pull-up resistors

Post by countzero »

Solved the problem. There was a non-trivial issue with cabling and one of the adafruit jumper wires was faulty. Furthermore, all maxbotix i2c sensors use the address 0x70, and I have two of them in the bus. I changed one to 0x71 which may or may not have loaded the address in the firmware on the first go.

Attached picture shows what I mean by non-trivial. 2 x maxbotix i2c sensors, 2 x maxbotix analog sensors, 1 x laser rangefinder, 1 x adafruit ultimate gps shield w. external antenna, 1 x adafruit 10dof, all connected to an arduino mega 2560 via assorted jumper cables, wiring and breadboard. Perhaps there are better ways of cable management but prototyping is usually messy.
DSC_0267s.jpg
DSC_0267s.jpg (162.7 KiB) Viewed 386 times

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adafruit_support_bill
 
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Re: 10dof imu and pull-up resistors

Post by adafruit_support_bill »

That's an impressive array of sensors there. Glad you got it all sorted. Thanks for the follow-up.

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