Simple Motor Controller 18v15 Analog Input Channel as ADC

I am working now on a simple motor controller 18v15 to control a geared dc motor with pid. The position of the output shaft is measured with a hall sensor with output range 0-3.3V. The SMC reads the sensor output by analog input channel 1. But I can only get a valid reading if the sensor output is less than about 2.5 V, which corresponds to a reading about 3000. With a voltage larger than 2.5V, it generates an error “one or more of your input channels is invalid” and i get 65535. Since the supply voltage 3.3V corresponds to 4095, the maximum limit, I don’t understand why the DAC readin saturates at about 2.5V / 3000. Could anybody help me?


I am sorry you are having problems using your Simple Motor Controllers. It sounds like your analog input settings might be set incorrectly and you have the maximum value set too low. How did you set the scaling values? If you have not yet, you might try using the “Learn…” button to calibrate your input channel. You can read more about this in the “Input Settings” section of the jrk user’s guide. If you continue to have problems, could you post your settings file and pictures of your setup? You can use the “Save settings file…” option under the File menu to store the settings.

- Jeremy

Attached is the settings file, and apparently the max. input for analog1 is 4055. But still, the maximum valid channel value is limited at about 3020. Is there any other problem with the settings? Thanks a lot.

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smc_settings.txt (2.97 KB)

I think I found where the problem was. I need to check the ignore poti disconnect. Apparently the resistance of my hall sensor is higher than the pololu suggested poti resistance.

It is not clear if you tried checking the “Ignore pot disconnect” checkbox. Have you had any issues since checking that box?

- Jeremy