PWM Reading & eCAP probblem with TI C2000 f28379d & Simulink

Hi, I'm trying to create a control system for a RC car with TI C2000 f28379d & Simulink, the project includes:

• On CPU2: four encoders for measuring wheel speed, reading PWM commands (steering/throttle) from TX-RX.
• On CPU1: IMU 6dof reading (I2CA), use of serials SCIA/SCIB and PWM output for servo/ESC (ePWM1/ePWM2)

The two programs communicate through the IPC blocks.

For encoders and PWM commands reading I referred to "RC_Demo_C2000_Control_Unit.slx" from https://it.mathworks.com/matlabcentral/fileexchange/63857-remote-control-racecar-using-simulink-and-texas-instruments-c2000

Testing the system I realized there are errors on reading commands: I read sporadically unwanted peaks (see image).

In the attached image I use a PWM with a high logic level of 1.5ms.

I did several tests with two different TX-RX pairs:

• one with 50Hz output frequency where there are sporadic peaks (PWM with high logic level of 1.5ms duration)
• the other with 100Hz output frequency where I get much more frequent peaks. (PWM with high logic level of 1.5ms duration)

Below is the configuration used:

• ENCODER_A:P24(eCAP1)
• ENCODER_B:P25(eCAP2)
• ENCODER_C:P14(eCAP3)
• ENCODER_D:P15(eCAP4)
• throttle:P16(eCAP5)
• steering:P29(eCAP6)

Here are the files I use: https://drive.google.com/drive/folders/1dfzXy4Ba3aSeai4P4Q269gKx3z1NeBnx?usp=sharing

Any ideas to solve the problem?

Thanks.

Answer 1

[Venkatesh Chilapur]

Please ensure Overflow/Underflow scenario are causing the behavior. You may want to log the values to ensure the inputs to ePWM block are within the desired range.