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6 years, 8 months ago.
Does PwmOut work on the K64F?
Hello,
I've been trying to set up PwmOut on my K64F all day without any luck. All I am trying to do is light up an LED with a PWM signal so that the period is 2 seconds with a 50% duty cycle. Ive been using the functions from the mbed handbook (see link below) but nothing works.
https://developer.mbed.org/handbook/PwmOut
No matter what I do the LED is either always ON or OFF but I can never get it to toggle. I am using an external LED not the on board as i know that one cannot be driven by PWM. I have looked around online quite a lot and some people are saying PwmOut does not work with K64F yet, is this true?
I have tried all the pins as well as both windows and Mac to compile the code and still no results. Could someone please correct the simple code below?
- include "mbed.h"
PwmOut led(PTC3); or any other PWM enabled pin
int main() { led.period(4.0f); 4 second period led.write(0.50f); 50% duty cycle, relative to period while(1); }
1 Answer
6 years, 8 months ago.
Hey, PWMOut does work. However, periods longer than 65 ms will not work for the reasons outlined here - https://github.com/ARMmbed/mbed-os/issues/2936#issuecomment-251883742
I have verified with a logic analyzer that a period of 65 ms works. For future reference, the mbed docs have moved here - https://docs.mbed.com/docs/mbed-os-api-reference/en/latest/APIs/io/PwmOut/, and they reference the most recent version of mbed OS. The new docs are also linked in the warning at the top of this page that you linked - https://developer.mbed.org/handbook/PwmOut
If you are looking to blink an LED at some interval, I would recommend looking at the Blinky example - https://docs.mbed.com/docs/mbed-os-handbook/en/latest/getting_started/blinky_cli
If you need to background the blinking LED, I would look into using mbed OS to run blinky in a separate thread like this example -https://developer.mbed.org/teams/mbed_example/code/rtos_basic/file/dc33cd3f4eb9/main.cpp
I will look into getting a warning about this added to the platforms page for K64F.