What is the sample time of C28x eQEP referring to?

I am planning do to an application for position-speed control of a motor using simulink and launchpad f28379D board. Does the eQEP continuously monitor the encoder's signals (A, B, and Z) in the background, updating the position counter in real-time, and only return the updated position at the specified sample time (e.g., every 0.001 seconds) without losing any data during the interval?

Answer 1

[Aabha]

Hi @Cristian,

The ‘Sample Time’ parameter of the ‘eQEP’ block in Simulink specifies the frequency at which the block reads the position counter value.

The frequency at which the microcontroller itself captures encoder signals is independent of the ‘eQEP’ Simulink block, and is dependent on the configuration of the microcontroller as follows:

• The frequency of capturing the counter values can be configured by modifying the ‘eQEP Capture Timer’ registers or ‘eQEP Capture Period’ registers on the ‘f28379d Launchpad’.
• The ‘eQEP Edge Capture Unit’ within the microcontroller can be adjusted to capture accurate data, especially for low-speed measurements.

Please refer to the ‘eQEP’ section of the TI documentation on ‘f28379d Launchpad’, to understand more about how the position data is captured:

https://www.ti.com/lit/ug/spruhm8k/spruhm8k.pdf?ts=1742964087792&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTMS320F28375D

Please refer to the documentation of the ‘eQEP block’ to get more information about the block parameters and configurations in Simulink:

https://www.mathworks.com/help/releases/r2024a/ti-c2000/ref/c28xeqep.html

I hope this answers your question.