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Melexis MLX90614 and I2C missing repeated start bit

Started by NameOfTheDragon, Jul 02 2015 08:19 PM

I2C Plus2 MLX90614 Repeated-Start-Bit

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#1 NameOfTheDragon

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LocationCanterbury, Kent, UK

Posted 02 July 2015 - 08:19 PM

Hi everyone. I'm trying to interface to an MLX90614 - IR non-contact temperature sensor, using the Netduino Plus 2's I2C bus, SDA and SCL pins. It's not working; I've hooked it up to my logic analyzer and I can see that the device is NAKing my read transaction.

MLX90614_NAK.png 21.19KB 0 downloads

From looking at other posts here, it seems that there is a missing repeated start bit that the device requires.

I'm confused about what exactly is needed. I can see there was a fix provided by CW2 and then incorporated into some alpha firmware by SecretLabs. I can see that the 'fix' went through several stages of evolution but the trail goes cold after the reference to alpha firmware.

What I'm confused about is where that leaves me, with Netduino 2 Plus, running .netMF 4.3.1. Is this fix now built in to the firmware and if so, how is it used?

Best regards,

Tim Long

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