Hi,

I've already purchased one of these cheap modules with STM32F103C8T6 chip onboard and my experience is that you can even use the mbed online compiler set for the NUCLEO-F103RB board. Just make sure that the generated binary does not exceed 64kB to fit into the flash of his smaller brother. Also the pin labels indicated on the board do match the NUCLEO board's blue/white pin names. Only the leading 'P' is missing and there is no underscore ('_') between the characters and digits :). However, please notice that not all pins from the NUCLEO-F103RB are present.

Thank you, for you library. Need help. I took advantage of your library. however, There is a problem. Function wait() does not work right. STM32F103C8T6 is stopted when I used two Timer or two TimeOut or use attach() twice. help!!!

Example:

while(1) {

myled = 0; begin = timer.read_us(); wait(0.2); end = timer.read_us(); pc.printf("Blink 0 delay %d\r\n",(end-begin));

myled = 1; begin = timer.read_us(); wait(1.0); 1 sec end = timer.read_us(); pc.printf("Blink 1 delay %d\r\n",(end-begin));

}

But same times wait(1.0); no 1 sec delay.

Putty on PC:

Blink 0 delay 200200 Blink 1 delay 1001000

Blink 0 delay 200200 Blink 1 delay 50194

Blink 0 delay 200200 Blink 1 delay 1001000

Blink 0 delay 200200 Blink 1 delay 1001000

Blink 0 delay 200200 Blink 1 delay 1001000

Blink 0 delay 200200 Blink 1 delay 22869

Blink 0 delay 200200 Blink 1 delay 1001000

Hello Slava,
Thank you for reporting the issue. Testato notified me about it recently too.
I have tried to run your code on a NUCLEO-F103RB board and the results were similar, i.e. delay times varying randomly. It seems there is a bug in the implementation of the us_ticker_read() function for the NUCLEO-F103RB platform in the current mbed library (rev. 125). After replacing the mbed library with the mbed-dev source files rev. 146 and modifying the wait_us(int us) function the results were on both NUCLEO-F103RB and STM32F103C8T6 much better (although not perfect yet). So let's hope that the mbed team will fix this issue soon (caused by incorrect values of counter variable calculated in the us_ticker_read() function). Until that I recommend you to use the "mbed-dev" library (instead of the precompiled "mbed") and modify the implementation of the wait_us(int us) function in the file
mbed-dev/common/mbed_wait_api.c as follows:

// ...

void wait_us(int us) {
    uint32_t start = us_ticker_read();
//    while ((us_ticker_read() - start) < (uint32_t)us);
    uint32_t now;
    do {
    	now = us_ticker_read();
    } while(((now - start) < (uint32_t)us) || (now < start));
}

Zoltan

thanks a lot for your analysis of the problem, but i do not understand why if I build the examples by online official compiler, it work (i do not have rpobelm on wait function) Instead if i build the same examples exported to EmBlock the problem appear. The online Mbed library version is not the same of the exported one ?

May you upload a version of the blink examples that include the mbed-dev library modified ? I'm new to Mbed so i do not know how add the mbed-dev library for modifie it.

thank you so much for sharing your work Testato

Hello Testato,
To import the mbed-dev library into your program please carry out the same steps as for any other library:

• Select you target program
• On the toolbar click on the "Import" button
• Select the "Libraries" tab
• Type mbed-dev into the "Search box" and then click on the "Search" button
• After a while you should see a line with info about the mbed-dev library
• Select that line (by clicking on it) and then click on the "Import!" button located just above the "Search" button

Once the mbed-dev library has been imported into your program (it takes a while) you can delete the original mbed library from it. Then try to recompile your project. Because also the mbed-dev sources have to be compiled it will take much longer then usually. After that you can try to modify the wait_us() function. Sadly, the code I suggested above did not take into account that the us_ticker_read() will roll over back to zero after about 71 minutes. So we better use the following :

void wait_us(int us) {
    uint32_t start = us_ticker_read();
    //while ((us_ticker_read() - start) < (uint32_t)us);
	uint32_t now;
    uint32_t end = start + us;
    if(end < start) {
    	// in case with roll over back to zero
		do {
			now = us_ticker_read();
		} while((now > start) || (now < end));
    }
    else {
    	// in case without roll over back to zero
    	while(us_ticker_read() < end);
	}
}

I can confirm that such program exported to "CooCox CoIDE" and re-built off-line behaves as the one built on-line.
Zoltan

Hello,
The solution I presented above works but it suggests to change an API function shared by all mbed boards (regardless how they perform). That isn't the right way to do it. We'd better be more specific and fix the issue just for the NUCLEO-F103RB as proposed at THIS link.
Zoltan