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Bizzie
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Joined: 06/07/2014
Location: Australia
Posts: 192

Posted: 02:51pm 12 Mar 2015

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As I will be starting some serious I2C work soon, I thought I would write a routine to detect I2C devices.

I tried this code on the ARMmite V12B:-

' I2C_detect

For Address = 0 To 127 Step 2
I2C Open 100,100
I2C Read Address,0,1,Data
If mm.I2C = 0 Then
Print "I2C device found at 0";Bin$(Address);"(";address;")",data
EndIf
I2C Close
Next

BUT it returns 128 devices!

Does anyone have a method to see what I2C devices are present?

Edited by Bizzie 2015-03-14

Rob White

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 06:44pm 12 Mar 2015

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Rob
Your address range is too large. 0 to 7 and 120 to 127 are not valid.

Have a look at this thread and you will find a test in there.

Bob

Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192

Posted: 08:45pm 12 Mar 2015

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Even changing my address range and using the code referred to gives a device on every address.
This is not what the referenced code leads me to believe. Is there something different about the ARMmite? or the discovery board?

Rob

Rob White

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 10:43pm 12 Mar 2015

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A couple of possibilities come to mind here. This firmware is out for testing. It may have bugs.

Is MM.I2C the variable name to use to test for I2C completion?
If it is then it may be not being updated and be stuck at 0.
Is the operation you are doing supposed to set the variable?

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10400

Posted: 11:22pm 12 Mar 2015

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I thought I would write a routine to detect I2C devices

I haven't looked at whether MM.I2C is set correctly on the STM32 - probably not.

Is testing for a I2C device at a specific address a real requirement? If so there is an internal function I use which I could expose through Basic

Syntax would be "dim integer i=i2ctest(address)" returns 0 for no device at that address or non-zero for device found

Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192

Posted: 12:54am 13 Mar 2015

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IMHO it would be good to know if a device is present especially when one has a new device and am not too sure of the address.
Is it a problem in the longer term though with various version changing in different directions?

Rob White

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