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It only takes a minute to sign up. How does one get current STM32F4 clock and set this constant according to it?

stm32 usleep

You could use a timer or the RTC with sub-millisecond accuracy instead. These are a lot more versatile and prevents busy-waiting.

They can also be easily configured as busy-waiting by adding an additional while loop when this is needed. There are existing example code for what you want to achieve. This examples shows how to get the current system clock etc. In my experience with STM32 it is that the standard peripherals library examples usually has the most answers when it comes to configuration.

There are a lot of examples out there. Also try the Keil examples. I've only used the STM32 series a little but can't think how it would be possible to make it totally clock independent. You could read the PLL settings but wouldn't have a way to know the crystal frequency without another time reference. There might be a few tricks I'm not aware of using things like the internal RC oscillator in the watchdog and other peripherals to provide that external reference but I'm not sure if it would be worth it and the accuracy wouldn't be as good as using a value calculated from the crystal frequency.

Personally I'd either read the family guide and calculate how many cycles the loop should take and calculate the constant from that if fairly high accuracy was required or otherwise just take a guess at the initial value and call with a fairly high value like mS and measure with a scope how long it's really taking and adjust from there.

In your case you mentioned milliseconds although above code mentions microseconds so your constant would be fairly large so maybe you could use something like the following without introducing an unacceptable amount of error:. Sign up to join this community.

C++ (Cpp) stm32_gpiowrite Examples

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stm32 usleep

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. So I use the interrupt routine to check each character received, but I somehow still cannot achieve what I want. When a command is processed, you can reset pRxBuffPtr and RxXferCount in the handle structure to their original values to start from the start of the buffer again. Interrupt response and processing time is often critical in embedded applications, and the HAL just wastes a lot of that.

If you have the complete HAL package installed, you could look at the examples for the L ow L evel interface. Since I stumbled over the problem today and could not find a good solution to it, I like to present a very simple one, using most of the HAL but avoiding the problems described The long version could be found in my post here You can make it work using HAL!

It may not be as elegant as other implementations but it is doable. In addition, I work with two buffers. While the Interrupt is filling one buffer the main loop is emptying the other. Learn more. Asked 2 years, 7 months ago. Active 1 month ago. Viewed 34k times. Bence Kaulics 3, 7 7 gold badges 23 23 silver badges 47 47 bronze badges.

Do it bare registers or HAL not both. Anyway HAL for the simple peripheral like uart? What do you mean by dublicating the buffer implementation?They also include a real-time clock and a set of backup registers that remain powered in Standby mode. A comprehensive set of power-saving modes allows the design of low-power applications. Distributor reported inventory date: This video is about the STM32L5, our recently announced ultra-low power microcontroller bringing a new security dimension.

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Witekio's teams are experienced in project management and help you choose and run methodologies most adapted to your project, be it Agile or Kanban, software factory, continuous integration.We will go through the assembler code generated from a small program written in C and come up with the prerequisites that must be in place in order for it to run. The following tools that are part of GNU Binutils :.

GNU Linker ld for linking. GNU objcopy for converting from elf format to binary format. Below is our C program. It defines variables ab and stores their sum in a variable named sum. The -S option will give us the corresponding assembler code, see section 3. We will divide it into parts and analyze. The first part defines ARM assembly attributes which do not correspond to any specific line of code.

Valid names are the same as for the -mcpu command line option. It is unclear for me what this means. A list of valid tags are available in the GNU Assembler gas documentation. Subsection zero will be used by default if not specified.

See GNU Assembler as. This information is necessary in order to allow the assembler and linker to generate correct code for interworking between Arm and Thumb instructions and should be used even if interworking is not going to be performed.

stm32 usleep

The presence of this directive also implies. Valid names are the same as for the -mfpu command line option. In this case main is a function symbol. See section 3. So basically we take the memory address stored in sp and copies to register r7 I think. In my understanding the so called frame pointer is stored in register r7. The frame pointer keeps track of where to restore the stack pointer when returning from a function. See Call stack at Wikipedia.

Run a C program bare metal on an ARM Cortex M3

So at the beginning of main we store the current value of frame pointer onto the stack. After that we store the current value of the stack pointer in register r7. This value in r7 shows what value sp shall be restored to when returning from the main function.

L2 loads the memory address of variable b into register r3. L2 is defined at the end of the assembler code:. Immediately following the end of main are the. L3 and. L2 labels.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. If I sending it via CuteCom console, it works great I receive a data and save it to two-dimensional array. If I'm using a QT Programm that schould make the same aim its not work, please help to find a bug!

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You need to determine if you're sending hex e. I think you're sending the latter, but the code talks about the former. Very confusing. Also, the text-to-binary conversion code makes no sense. Also, why are you writing hextest. Text to binary?

You want to say that.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. I'm trying to implement a sleep mode in a microcontroller to save power but I don't quite understand why it behaves the way it does.

I started with a simple program that puts the CPU into sleep mode at the beginning of the execution. Then it waits for the external interrupt to wake it up, execute the interrupt and continue with the main program. When a processor issues a WFI instruction it can suspend execution and enter a low-power state. It can remain in that state until the processor detects one of the following WFI wake-up events:.

PM was set to 0, would preempt any currently active exceptions. If my understanding is correct, the second line applies in this case.

Which means, that calling any interrupt regardless of its priority would wake up the processor, since the WFI was called from the main. For information, all the implemented interrupt priorities are set to 0 except for the EXTI, which is set to Now this is what actually happens. This is confirmed even during the debugging, while I inserted a breakpoint in the interrupt service routine.

After letting the code run, it succesfully stops at the breakpoint. If I then continue debugging with a step-by-step function, the program jumps to the WFI instruction upon which it continues to the main, since debugging can cause to terminate the WFI. Given my understanding, if the CPU is in WFI, it should continue with it's operation wherever it left off as soon as any interrupt get called.

Setting that to 1 would cause exactly what you've described:. Configures sleep-on-exit when returning from Handler mode to Thread mode. Setting this bit to 1 enables an interrupt-driven application to avoid returning to an empty main application.

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I'm sure this is something trivial, but being relatively new to MCU development I'm stumped.

Stm32 Delay Using Timers or Systick

Wouldn't you expect usleep to be architecture dependent? And need to implement it yourself? I'd wager there is a bunch of stuff in stdio. Thanks Clive - that's exactly the info I needed. Much appreciated. All rights reserved STMicroelectronics. Cookie Notice Cookies and similar technologies enable us to provide you with an optimized user experience and functionality of our website.

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stm32 usleep

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