I have an application that I am porting from the Keil IDE to build with the GNU toolchain due to license issues. I have successfully be able to set up, build, flash and run the application on the d...

I'm using a STM32F107 cortex m3 microcontroller. I'm using the Keil uvision IDE for the project. I have an application which is running properly at the starting location i.e 0x0800 0000. If I chang...

Introduction I am a student who wants to roughly measure the interrupt latency of ARM Cortex-M series chips without using an oscilloscope. However, I have encountered a very peculiar issue that has...

In the ARM documentation, it mentions that The Cortex-M4 processor supports ARMv7 unaligned accesses, and performs all accesses as single, unaligned accesses. They are converted into two or mo...

I'm trying to get multicore working on my pico, #include <stdio.h> #include "pico/stdlib.h" #include "pico/multicore.h" void core1_main() { stdio_init_all(); while (1...

I am confused with the clock system on my STM32F7 device (Cortex-M7 microcontroller from STMicroelectronics). The reference manual does not clarify the differences between these clocks sufficiently...

On the STM32F103, the erasing of a flash page takes 20ms during which the core stalls for me. It's not clear from the ST PM00042 Flash programming manual whether the core would always stall when er...

I'm writing some assembly code for the Cortex-M4, specifically the STM32F407VG found in the STM32F4DISCOVERY kit. The code is extremely performance-sensitive, so I'm looking to squeeze every last c...

I used "Exhuberant ctags" to index all the tags from my c-project. The c-project is embedded software for a Cortex-M7 microcontroller. The result is a tags-file. I'm trying to read this file and un...

I've been looking for a list of the opcodes used in ARM Cortex M3/M4/M4F, without luck. There are plenty of [online] references to the 32-bit format of ARM instructions. References to Thumb-2 instr...

I have an object that has an address that is not 4-byte aligned. This causes a HardFault error in the cpu when there is a STR instruction saving 2 registers. This is the generated code: 00000000 &...

Pre ARMv6 MPUs/MCUs have SWP instruction (e.g. good ole and still alive ARM7TDMI). In ARMv6 architecture LDREX/STREX pair has been introduced and SWP removed. However with one exception – ARMv6-M (...

According to the Rust Embedded Book about concurrency, one of the better ways to share some data between contexts is using mutexes with refcells. I understand how they work and why this is necessar...

I am working on an ARM Cortex-M3 controller which has the Thumb-2 instruction set. Thumb mode is used to compress the instruction to a 16-bit size. So size of code is reduced. But with normal Thumb...

I have the following instruction: mov r1, r7 in my assembly code but after looking into disassembly, I've found that actual generated code was adds r1, r7, #0 I checked with ARMv6-M Architecture Re...

In the Cortex-M3 instruction set, there exist a family of LDREX/STREX instructions such that if a location is read with an LDREX instruction, a following STREX instruction can write to that address...

Working a lot with microcontrollers and C++ it is important for me to know that I do not perform dynamic memory allocations. However I would like to get the most out of the STD lib. What would be t...

I want to generate a sine signal in C without using the standard function sin() in order to trigger sine shaped changes in the brightness of a LED. My basic idea was to use a lookup table with 40 p...

Does anyone have (or can easily write) an optimal inline assembly function for the ARM Cortex M0+ processor in Thumb mode to multiply two 32-bit numbers and return a 64-bit number? As the M0+ does...

I am writing a code for Cortex-M3 cpu and I am performing unit testing using qemu-arm binary. For now everything works just fine. But I am wondering If I am able to test whole system using qemu-sys...

I am compiling this code for a Cortex M7 using GCC: // copy manually void write_test_plain(uint8_t * ptr, uint32_t value) { *ptr++ = (u8)(value); *ptr++ = (u8)(value >> 8); *ptr++ = (u8)(...

I am reading through Cortex M4 TRM to understand instruction execution cycles. However, there are some confusing description there In Table of Processor Instuctions, STR takes 2 cycles. Later in L...

I have a 64 bit integer variable on a 32 bit Cortex-M3 ARM controller (STM32L1), which can be modified asynchronously by an interrupt handler. volatile uint64_t v; void some_interrupt_handler() { ...

In a realtime application¹ on an ARM Cortex M3 (similar to STM32F101), I need to poll a bit of an internal peripheral's register until it's zero, in as tight a loop as possible. I use bit banding t...

I've been experimenting a bit with execution from RAM and flash memory on embedded systems. For rapid prototyping and testing I'm currently using an Arduino Due (SAM3X8E ARM Cortex-M3). As far as I...