Issue with Incorrect Encoder Values – SparkFun Auto pHAT and Hobby Motor with Encoder

[Ed81]

Dear Customer Service Team,

I am currently using the following products:

• SparkFun Auto pHAT for Raspberry Pi (ROB-16328)
• Hobby Motor with Encoder - Metal Gear (ROB-16413)

I am encountering an issue where, when reading the encoder values, I occasionally receive incorrect readings. For example, out of 50 encoder counts, I sometimes get a value like “-120” in the middle of the series, and then the values continue as expected (e.g., “50”).

As this is my first time working with encoders, I am wondering if this behavior is normal, or if I might be doing something wrong.

To mitigate the issue, I have implemented a kind of damping in my code: values that deviate by more than 15% from the previous reading are ignored. However, I am wondering if there are other, more effective approaches to handle this problem.

Has anyone experienced something similar, or can suggest ways to improve the accuracy of the encoder readings?

[jremington]

@Ed81

I sometimes get a value like “-120” in the middle of the series, and then the values continue as expected (e.g., “50”).

Please post the code, using code tags.

If you are using interrupts, that behavior is a typical result of not following the stringent rules for interrupt coding.

[Ed81]

I am using the code from the SparkFun Auto pHAT Hookup Guide. Here is a screenshot of the described effect.