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OneWire with DS18B20
Posted: Wed Aug 11, 2021 6:02 am
by kiloWATT21
Hi,
i'm using a board with STM32L051K8, and i'm having trouble reading temperature from DS18B20.
I have tried all kinds of libraries and codes without the library, but non of it seems to work.
Is the L0 chips just too slow for OneWire protocol. Do i have to use the solution using USART solution with the diode (
https://cnnblike.com/post/stm32-OneWire/ )?
Re: OneWire with DS18B20
Posted: Wed Aug 11, 2021 7:30 am
by fpiSTM
Hi
@kiloWATT21
if you use the
STM32 core then simply use this library:
https://github.com/PaulStoffregen/OneWire
Re: OneWire with DS18B20
Posted: Wed Aug 11, 2021 7:35 am
by ag123
many libraries may not work 'out of the box' if they use atmega specific features e.g. hardware timers
https://create.arduino.cc/projecthub/Th ... ino-9cc806
https://lastminuteengineers.com/ds18b20 ... -tutorial/
what can be done is to review the codes and adapt/port it across to use stm32timers
examples for using the stm32 hardware timer are here (STM core)
https://github.com/stm32duino/wiki/wiki ... er-library
it is quite easy once you get used to using the stm32 hardware timers, basically 'bit bang' the signals on a port.
you won't need a uart for it as the signals are pretty much 'slow' > 10us.
try the blink examples with stm32 hardware timers to figure out how to control duration, duty cycle, interrupt callback etc
hardware timer codes looks mostly like this
Code: Select all
HardwareTimer *Tim1 = new HardwareTimer(TIM1);
void Update_IT_callback() {
//timer calls this every period
//e.g. digitalWrite(pin), digitalRead(pin);
}
void setup() {
Tim1->pause();
Tim1->setMode(channel, TIMER_OUTPUT_COMPARE_PWM1);
Tim1->setOverflow(10, MICROSEC_FORMAT); // 10 microseconds
Tim1->attachInterrupt(Update_IT_callback);
Tim1->refresh();
Tim1->resume();
}
void loop() {
// other sketch codes goes here
// you can still pause(), refresh(), resume() the timer from here
// the connection between here and the timer callback is to use global variables or arrays
// use a global variable to manage state
}