That would be an I2C error. Um, did the init method succeed?
The error is caused by this code: https://github.com/openmv/openmv/blob/master/src/mlx/src/MLX90640_API.c#L48
Um, also, keep in mind the FPS on the MLX sensor. So, you cannot run it at a very high sample rate in hz. The default sample rate we supply is about the max that you can hit. If you go lower with it that also might be better. If the I2C connection is good then what’s happening is that the MLX sensor is running too fast and is overwriting it’s internal frame buffer before we have a chance to read it out over I2C. The MLX API driver throws an error when this happens and that’s what you are seeing. Slowing down the sensor refresh rate will fix the issue. Given the resolution of the MLX sensor it’s not actually possible to pull the image at the max refresh rate they support over I2C easily without going above 400 KHz which then starts to cause issues related to wire length.
I can speed the I2C bus up however if you think it might be needed… would need to change our driver for it though to support multiple freqs.