Cannot run the motors with a single speed parameter

[yuanyanhui]

Tried the example on ESP32, the motors did not spin with a single speed parameter.
motors.drive(0.5, 500);
With two separate speed parameters, the motors worked fine.
motors.drive(-1.0, 1.0, 500);

[yuanyanhui]

Tried again, it seems the motors can only run at full speed. When setting the speed at 1.0, the codes worked without any problem.
motors.drive(1.0 500);
motors.drive(-1.0, 1.0, 500);
Any speed other than 1.0, the motors would not move.

Tried SparkFun TB6612 library also, the motors were changing speed as expected.

[vincasmiliunas]

Hi,

it might be due to PWM pulse frequency and how your motors react to it. The default value is set to 20kHz to avoid being audible. It's located at the top of the file TB6612FNG.cpp https://github.com/vincasmiliunas/ESP32-Arduino-TB6612FNG/blob/master/TB6612FNG.cpp#L6

Lowering it to 1kHz might help:

#define DEFAULT_LEDC_FREQ 1000

[yuanyanhui]

Hi,

Thank you for your reply.

The problem was not with the frequency setting. I tried different frequencies. None worked. I did another test by commenting the following line of code in TB6612FNG.cpp and set v=0.2. The speed of the motors lowered as expected.

void Tb6612fngLedc::write(float value) {
// const auto v = std::max(0.0f, std::min(1.0f, value));
const auto v = 0.2;

[vincasmiliunas]

Hey, thanks for debugging it! :)

It's another gotcha of assuming C functions work like C++ ones. Previously min and max worked accidentally (they were leaked by Arduino.h, later disappeared), now it's the abs function. The C abs actually takes an int, so it's input get truncated from float to int, thus 1.0 becomes 1 and 0.5 becomes 0.

I've pushed a commit, should fix it. Thanks again!

[fmalekpour]

ledc.write(std::abs(velocity)); works, can you bump the version?

[vincasmiliunas]

Hi, sure, it's up.