72 MHz dividing by 100 code


int outputPin = PA6; //output pin

which simple code?

Maybe someone know how to write such code ?

one typical process would be to look up the datasheet and figure out how the clock division works.

another typical process would be to beg someone else to write it for you.

Three historical references:

http://docs.leaflabs.com/static.leaflab … timer.html

http://docs.leaflabs.com/static.leaflab … imers.html

http://docs.leaflabs.com/static.leaflab … timer.html

Forum discussion: http://forums.leaflabs.com/forums.leafl … ml?id=1361

void loop() {
mypulse = 5; // 0<=mypulse<=period, this is my High pulse length in useconds
duty = map((int32_t)mypulse, 0, (int32_t)myperiod, 0, (int32_t)maxduty);
pwmWrite(PA7, duty); // 0<=duty<=maxduty
while(1){};
}


#include <SPI.h>
int outputPin = PA6; //output pin

*/

duty = map((int32_t)mypulse, 0, (int32_t)period, 0, (int32_t)maxduty);

^

exit status 1
‘period’ was not declared in this scope


pwmtimer.setPrescaleFactor(4); // Timer input clock Prescaler = 1 (= 36MHz input ?)
pwmtimer.setOverflow(0.5); // PWM Period width for 720kHz ?


pwmtimer.setOverflow(100); // PWM Period width for 720kHz ?
pwmtimer.setCompare(TIMER_CH2, 50); // PWM High Pulse width is 50% duty (1:1)pwmtimer.setOverflow(100); // PWM Period width for 720kHz ?
pwmtimer.setCompare(TIMER_CH2, 50); // PWM High Pulse width is 50% duty (1:1)

void loop() {
}


void loop() {
}


STM32 BLuePill PIN diagram.JPG (209.41 KiB) Viewed 338 times

// Use timer 2
HardwareTimer pwmtimer2(2);

}


#1
function y = sin3(x)
n = 1 : 1000;
for i = 1 : length(x)
y(i) = x(i).*prod(1 - x(i)^2 ./ (n*pi).^2);
end

[ted – Wed Jan 03, 2018 1:03 pm] –
<…>
Will disabling those lines make microcontroller less busy ?
I guess not much.

There is a danger to my not responding to this statement as it may be read and interpreted by a non-hardware user as meaning that within the uC, disabling peripheral interfaces will/would make the uC run faster. This is not the case.

If one studies the STM32 architecture document, one will note that the microcontroller has internal buses that connect various subsystems. Disabling a subsystem “may” reduce the chip power usage, but generally subsystems that are not utilized are not initialized and configured, so power dissipation of non-used peripherals should be minimal.

What does make a microcontroller “busy” is the start-up/initialization code and then user code that exercises the various peripheral activities. Some peripheral devices such as PWM consume bandwidth when they are configured but afterward do not consume any user execution time unless something is changed by user code. Of course, when PWM is active, electrical power is consumed because that device is active and clocking to an output pin.

void loop() {
}


Probably you could try adding:
afio_remap(AFIO_REMAP_TIM3_PARTIAL);

Anyone hoping to be successful working with timers need to be familiar with the specific STM32 Reference Manual. Yes, it is a big PDF but it is also the bible for any aspiring engineer. Beyond the PDF, there are many smaller dissertations which will help provide some glue knowledge to help in understanding the details around timers. All commonly available references can be found with only a single Google query.

To everyone posting in the forum… THINK BEFORE YOU POST
In reviewing this thread, the Op has done what many of us do from time-to-time; that is, posted and then gone back and deleted a post.
In this case, several posts were deleted in sequence. A thread should be continuous in thought and response and deletes, especially multiple deletes, leaves the thread discontinuous and hard to follow. DO NOT DO THIS… If you must edit a prior post, then at least strike-through like this the old or add some key to let the reader know that the text was time-shifted, edited, amended, etc. Everyone is responsible for being a good citizen in the forum, so think before you post.

Ray
(Global Moderator)

Posts cant actually be deleted, the system just hides them.

Ray. does moderator privileges allow you to show them again, if not I’ll see if I can change the settings

See §9 General-purpose and alternate-function I/Os (GPIOs and AFIOs)

A GPIO pin can have several functions but not at the same time. Up to you to configure it depending of your need.

Software remapping of I/O alternate functions
To optimize the number of peripheral I/O functions for different device packages, it is possible to remap some alternate functions to some other pins. This is achieved by software, by programming the corresponding registers (refer to AFIO registers. In that case, the alternate functions are no longer
mapped to their original assignations

[ted – Wed Feb 28, 2018 7:52 pm] –
Here is the drawing clarifying my question – why A is not equal B .
fpiSTM – thanks for your suggestions, it not working yet, but is it some point to start.

Those are alternate pins. The MCU allows you so select if a peripheral uses one pin OR another pin, but you can’t use 2 pins at the same time for the same function. It’s alternate, one or the other.
all that is in the reference manual, it’s long, but you should read thru it to understand the peripherals. No amount of QA in the forum will cover what the reference manual can teach you.
Furthermore, you can’t do a sine wave with PWM. The times can output 0 or 1, low or high, but not an analogous signal. You need a DAC for that, and the bluepill MCU doesn’t have a DAC, so no sine wave.