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MThat
MThat
Associate II
August 6, 2018
Question

Trying to adapt a library, getting a syntax error,

  • August 6, 2018
  • 4 replies
  • 1506 views

Good day, everyone.

This is the library I'm trying to us with the STM32f103.

https://github.com/rogerdahl/stm32-tm1637

Most all of the work was already done as this IS an stm32 library.

I am however getting this error:

compiling main.c...
..\libraries\stm32-tm1637-master\stm32-tm1637-master\stm32_tm1637.c(143): error: #130: expected a "{"
 __asm__ __volatile__("nop\n\t":::"memory");
..\libraries\stm32-tm1637-master\stm32-tm1637-master\stm32_tm1637.c(143): error: #18: expected a ")"

The code snippet that this piece is complaining:

void _tm1637DelayUsec(unsigned int i)
{
 for (; i>0; i--) {
 for (int j = 0; j < 10; ++j) {
 __asm__ __volatile__("nop\n\t":::"memory"); // This is LINE 143
 }
 }
}

 I'm not sure where exactly those brackets are supposed to go. This is a level of programming outside of my basic understanding of... making an led blink...

    This topic has been closed for replies.

    4 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 6, 2018

    A less clumsy and more portable implementation would look like

    void _tm1637DelayUsec(unsigned int i)
{
 volatile unsigned int j;
 while(i--)
 {
 for(j=0; j<10; j++)
 {
 __NOP();
 }
 }
}

    Using in-line assembler has tool-chain specific limitations. You don't specify what you're using, guessing Keil. But __NOP is a CMSIS compliant form.

    Volatile is used so the compiler doesn't optimize out a pointless looping construct.

    With such loops you'd likely need to calibrate the loop iterations as this is code and chip speed specific. ie Toggle a GPIO pin and scope

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    waclawek.jan
    waclawek.jan
    Super User
    August 6, 2018

    Clive, isn't it __NOP() ?

    The inline assembler from the original post may be gcc-specific, the error messages don't seem to be gcc.

    In STM32s, it may perhaps be easier to implement us-granularity loopdelay using timers (maybe even systick).

    JW

    MThat
    MThatAuthor
    Associate II
    August 6, 2018

    The Two of you have provided a working solution, thank you!

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 7, 2018

    Yes

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