Servo.attach() call to Servo::write() before min/max are configured leads to issue when writting angles in degrees

[jan019]

Describe the bug
The Servo library calls the write() function within the attach() function

Arduino_Core_STM32/libraries/Servo/src/stm32/Servo.cpp

Line 124 in 641f3d8

write(value);

before configuring this->min and this->max values

Arduino_Core_STM32/libraries/Servo/src/stm32/Servo.cpp

Lines 126 to 127 in 641f3d8

	this->min = (MIN_PULSE_WIDTH - min) / 4; //resolution of min/max is 4 uS
	this->max = (MAX_PULSE_WIDTH - max) / 4;

, which however need to be configured for write() function to work correctly when the servo position is set in degrees. The function write() uses the this->min and this->max values to map the passed value in degrees between min and max https://github.com/stm32duino/Arduino_Core_STM32/blob/641f3d8883e9a7220f65dded355dc32e218a990d/libraries/Servo/src/stm32/Servo.cpp#L156/

To Reproduce

int min = 40;
int max = 70;
int value = 40;

// on first call to attach, the write is called with a different value in this->min and this->max than on following calls
Servo.attach(pin, min, max, value)

• STM32 core version: 2.7.1

The write() function should either not be called in the attach() function at all, or it must be called after this->min and this->max are configured.

[fpistm]

Hi @jan019
Thanks for the detailed report.
It seems logical. Could you submit a PR ? I guess configuring the values before the write call instead of after is enough.

[jan019]

Hi @fpistm, thanks for checking this out. I will submit a PR later today with configuring the values before the write call instead of after (I have tested this and it works well).