Melexis to PICAXE

[Armp]

The total voltage peak supply with my tired AA batteries.

Well there's your answer... The MLX90614xSF-Axx is spec'd down to 4.5v, and DOES NOT WORK reliably much below that.

Run it with 4.7k at 5v, and all will be well.

For other devices RTFM.

This is what the spec says about the Clock line.



Here are the SCL and SDA plots for my 614 running at 5v, i2cslow. The clock level is just over 3.3v, and tracks with Vdd.

 

[Profw]

Unless it's the 3.0 V version.