Arm

The program counter in ARM Cortex processors is stored in the PC (program counter) register. The PC register contains the address of the current instruction that is being executed by the processor. It is 32 bits wide and is updated during each fetch cycle to point to the next instruction. Overview of Program Counter in…

When mixing ARM and Thumb code on the Cortex M3, it is important to be aware of ARM/Thumb interworking issues that can arise. Careful coding practices can avoid problems with interworking and keep your code running efficiently. ARM and Thumb Instruction Sets The Cortex M3 processor supports two instruction sets – the 32-bit ARM set…

The Cortex-M3 processor supports both Thumb and ARM instruction sets. Thumb instructions are 16-bit long while ARM instructions are 32-bit long. Using Thumb instructions reduces code size, but ARM instructions can provide better performance. This article provides a detailed comparison between Thumb and ARM instructions when programming the Cortex-M3 processor. Overview of Thumb and ARM…

Cross compiling with GCC for the ARM Cortex M3 allows developers to build code on a host system like Linux or Windows and generate binary files that can run on the target Cortex M3 platform. This provides efficiency and flexibility during development. The key steps are installing a Cortex M3 toolchain, setting up the development…

A bootloader is a small program that loads the main application program into the microcontroller’s memory when the device first powers on. The bootloader typically initializes the microcontroller’s hardware, validates the integrity of the main firmware image, copies the main firmware from external flash storage into RAM, and then transfers execution to the main firmware….

When an Arm v8-based system powers on, it goes through a complex boot process to load and initialize the operating system. This boot process involves multiple stages, from low-level firmware executing to load the kernel, to starting init processes that fully initialize userspace. Understanding the full Arm v8 boot flow provides insight into the boot…

The ARM Cortex-M3 is a 32-bit processor core licensed by Arm Holdings. It is part of the Cortex-M series of microcontrollers and is designed for embedded applications requiring high performance and low power consumption. The Cortex-M3 core has a 3-stage pipeline, uses the Thumb-2 instruction set, and includes features like a Memory Protection Unit, low…

The main difference between pre-indexed and post-indexed addressing modes in Arm Cortex M is that in pre-indexed addressing, the offset is added to the base register value first and then the result is used as the address for the memory access operation. In post-indexed addressing, the value in the base register is used directly as…

The Cortex-M3 is an ARM processor core designed for embedded and IoT applications. It is part of ARM’s Cortex-M series of cores, which are optimized for low-power consumption and high efficiency in resource-constrained devices. The Cortex-M3 operates at a maximum clock frequency of 100 MHz. Overview of the Cortex-M3 The Cortex-M3 CPU was first introduced…

Task switching on Cortex-M microcontrollers can be done using either the Main Stack Pointer (MSP) or Process Stack Pointer (PSP). The MSP is used by default for the main thread of execution, while the PSP is used for context switching to other threads. Switching from using MSP to PSP offers some advantages for multithreaded applications…