Questions tagged [cortex-m3]

is an ARM 32bit RISC processor core for microcontrollers

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Does Cortex m3 parse a firmware code from -code D-code bus?

I'm trying to understand the reason of I-code and D-code bus in Cortex M3 and how simple arbiter into single slave(Flash/ROM/RAM) can make an improvement performance of device. (https://community.arm....
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STM32F103 Debug Error - Cannot Access Target

Im having problem at debugging, tried to load basic led toggle program for test purpose and its work fine but when i tried to debug it, im getting " Cannot Access Target, Shutting Down Debug ...
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Help with LDM instructions on ARM Cortex-M3 processors

Consider the instruction LDM R4!, {R0-R3}. Does the instruction LDM R4!, {R0-R3} load the MEMORY ADDRESS pointed to by R4 to R0 ...
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Atmel SAM3X8E (cortex M3) MPU confusion

The SAM3X8E has a MPU, what I am confused about is how to combine both SRAM and FLASH into the same protected memory region since they live at different contiguous region addresses. Is this possible? ...
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LDR, LDRD and STR instructions with immediate offset in ARM Cortex-M3

The Cortex™-M3 Devices Generic User Guide explains the instruction LDRD R8, R9, [R3, #0x20] as "Load R8 from a word 8 bytes above the address in R3, and load ...
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Flash and run a .hex file on a different Microcontroller with bigger flash from the same Cortex family

Is it possible to flash and run a compiled code (.hex-file) for a specific Microcontroller (for example STM32F205RC) on a Microcontroller from the same family with bigger flash-memory and RAM (without ...
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Most efficient way to split data into segments and fill them into bit masks

Background: I need to write 32 bit data to a receiving instrument, the source of the data is a 32-bit read-only register. This project is time-critical, every clock cycle matters. That requires 32 ...
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What is DMIPS/MHz?

As I was reading the datasheet of STM32F103C8T6, I saw that it had 1.25 DMIPS/MHz (Dhrystone). What is DMIPS/MHz? I am adding the link to the datasheet here
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Bus Fault Handler when writing to a memory provided by a linker script

I have to work with code written by someone else for the Cortex M3-based board. I know that this code is supposed to work and it used to pass its integration test: the code is flashed to the board ...
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Is a STM32F103 able to handle 74.25MHz from an image sensor?

So I have this project in my mind where I want to read pixel data from an image sensor via a microcontroller (e.g. STM32F103) and then display the image on a screen. The image sensor I have in mind ...
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ARM Cortex M3 Systick Question

I ran across some code that is being used to create a 1ms timer in polling mode, not interrupt mode. However, I'm having a hard time wrapping my head around the function. So the Systick is ...
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Cortex-M3, Code region vs SRAM/RAM

In the ARM Cortex-M3 processor core, the memory map contains: a Code region, SRAM and a RAM. What makes the use of the code region different than the other memories? In addition, what is the nature of ...
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bootloader jump to application address problem

I have written a bootloader for my board, but it generates a hard fault when it jumps to the application code. My error is like this question: Bootloader jump to main application problem using STM32 ...
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4 answers
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Bare-metal start-up code for Cortex M3 .bss region initialization

I have developed inspired from here a bare metal start-up code for arm cortex M3. However, I encounter the following problem: suppose I declare an uninitialized global variable, say of type unsigned ...
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Migrating Cortex Application from Development Board to microcontroller chip [closed]

I have been working on different micro-controllers and I am new to Arm cortex architecture. I have developed an application on NUCLEO-F207ZG (powered by STM32F207ZG). The application is supposed to ...
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Cortex M3 reset handler with vector table relocation

I have a system with an STM32F103, which has a bootloader and a main app. Now, the main app is offset from the beginning of the flash to make room for the bootloader, and on cold boot the firmware is ...
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J-Link programmer in Windows 8 don't work

I use the J-Link programmer in Windows 8. A few days ago, my programmer hanged and the LEDs stayed silent, and I, with the help of the Internet, was again using the SAM-BA software to install the ...
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Unable to get SPI working on STM32 Cortex-M3 (Blue Pill)

I am trying to connect to an RFM95W module using the Cortex-M3 Blue Pill from ST. I am an embedded novice but know my way around linux, so I used the below code on an Rpi3 to connect to the chip and ...
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SoftConsole VS Keil for Smatfusion2 or any other development environment?

In order to program the ARM Cortex-M3 processor which is embedded in the Microsemi FPGA board SmartFusion2, I think there is two possibilities (correct me if wrong): Keil MDK (Microcontroller ...
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4 votes
2 answers
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Understanding ARM instruction for numerical literal

I have done an instruction trace while trying to find a bug on a Cortex M3. There is one part of the command I cannot understand. STRB R1, [R3], #+0x01 According ...
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Configuring Registers in ARM Cortex M3

I've been learning to program LPC2148(ARM7) microcontroller, and today I got hold of an LPC1768(Cortex M3) board. By referring it's manual, I tried to make a LED blink program and did it as follows, ...
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Design an instruction using Thumb-2

I'm studying the Cortex-M3 of ARM. The problem statement reads: We're going to use a Harvard architecture with the following addressing capabilities: 32M words of code and 16-bit data words. The ...
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Can the ARM processor be switched to unprivileged mode inside handler mode?

In the ARM documentation it is stated that: The processor supports two operation modes, Thread mode and Handler mode. Thread mode is entered on reset and normally on return from an exception. ...
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Interrupt priority in STM32F103RB

I got a doubt about an interrupt grouping in stm32f103. In programming manual of microcontroller I found 5 ways to configure it. But, while debugging, I found 8 ways. How is it possible to get ...
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Mysterious hard-fault when I step over

This question was rewritten to remove several updates and improve clarity. I have a Cortex M3 based (and rather obscure) MCU. I have a rather big project, written in C++, in Keil MDK5 with armcc ...
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Why does SendChar code of UART different between IRQ and Polling?

Now I'm trying to analyze STM32F103 Cortex-m3's UART code in IRQ and Polling mode. Ans I found 2 types example code such as the below. This is IRQ. ...
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2 answers
566 views

Load and store CPU registers in application context

I just recently started working with a bare STM32F103C8T6 (an ARM Cortex M3) and ran into some difficulties. I have set up a SysTick_Handler to switch the current ...
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What is the relation between DAC peripheral bus and conversion/settling time

Going through the datasheet and the LPC17xx user manual, what is quite evident is how to select the various clocking options for the peripheral clock divider, i.e: ...
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What is the least amount of time that I can measure using STM32F1x Timers?

I am working with STM32F107 on a custom board, the board has 12MHz crystal. I want to measure 1 micro second precisely, but I am unable to do so. I have used STM32CubeMX to set the core clock at 72MHz ...
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STM32F103 ARM - Modifying Clock At Runtime - FLASH Latency

I am having b it of confusion regarding changing the clock tree of an STM32F103 Cortex M3 at runtime and I am hoping someone can help me with it. I am using a development board which has a 8Mhz HSE ...
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JTAG, OpenOCD and Atmel SAM3X

I'm trying to set up OpenOCD debugging through a JTAG port on a custom board with an Atmel ATSAM3X8E microcontroller. OpenOCD is running on a Raspberry Pi using the bcm2835 native GPIO. The JTAG ...
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4 votes
6 answers
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What instruction on the STM32 consumes the least amount of power?

The ADC module of the STM32 is used in my application which is very sensitive to power consumption. In this application, the ADC is required to work only at 20 samples per second. Using the DMA uses ...
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2 votes
1 answer
336 views

How to read/write from a CPU using a usbWiggler?

Reading the Macraigor API for the usbWiggler MacraigorApi_ JtagScanlO ...
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3 votes
2 answers
947 views

Programming SRAM over SWD

I'm attempting to program a Cortex M3 based microcontroller over SWD, more or less from first principles. I've written an SWD interface library and have it running on a second micro. I've largely ...
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Reading 2 Quadrature encoders using a single Arduino Due

I am working on an autonomous robot in my summer vacations. I am currently working on running the motors of my robot in a closed loop. In order to do so, I have to interface two Quadrature encoders of ...
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Can't understand a variable in the formula used to determine CDTY to set duty cycle of PWM on cortex M3 (SAM3X8E)

I want to generate complementary PWM on an Arduino due. For that purpose I am programming the cortex M3 using the PWMC library. In order to set the duty cycle I have to set a value in CDTY channel ...
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349 views

LPC1769 PC Communication

I am using LPC1769 micro controller and planning to use one of its serial (UART) port for PC communication. It has 4 UART ports (UART0,1,2 and 3) For PC communication purpose, can I use all ports or ...
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2 votes
1 answer
361 views

Howe to do a sam3x single channel ADC conversion

I have a Sam3x (Arduino Due hardware, but I don't use the Arduino IDE or libraries, and I don't use the Atmel libraries, just the register interface in sam.h). I have multiple pins configures as ADC ...
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1 vote
1 answer
136 views

3 mic sound direction locator solution?

I am building a robot toy. When a sudden surge of sound occurs, I wish to calculate the approx position of the sound source. I am going to place 3 analog mics on the edge of my round shape PCB, each ...
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Atmels AtSAM3s gets a bit warm running a test code on my dev board. Is there a problem?

I have a dev board developed by myself. I was using At91SAM7S256 but now I'm migrating to it's successor ATSAM3S8B. The MCU on the dev board for SAM3S gets warm. I am searching for someone with ...
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1 answer
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STM32 Standard Peripheral Library (SPL) - Modify SPI Configuration

I am using the STM32 SPL library with an STM32F103C8 microcontroller. As part of the project, I am using the SPI1 peripheral to interface with an SD card. Initially the SPI speed must be kept under ...
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1 answer
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LPC17xx internal pull-ups on JTAG etc

The the NXP LPC17xx Cortex-M3 family has internal pull-up resistors on some important pins such as the JTAG, NMI, Bootloader-select pin etc. While reading the data-sheet I learned that the pull-up is ...
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3 votes
3 answers
366 views

Finding maximum source impedance for A/D converter (SAM3X8E ARM Cortex-M3)

I would like to find out what is maximum recommended source impedance for A/D converter on Atmel SAM3X8E ARM Cortex-M3 microcontroller. I tried to follow the example of this excellent answer, which ...
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Cortex M3 GPIO address (LM3s300)

I had a little confusing regarding the address of GPIO_PortA As mentioned in datasheet: Based address of GPIO PortA:0x40004000 and GIOP_DATA has Offset : 0x000 which mean the address of GPIO_PortA = ...
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1 vote
1 answer
202 views

Necessary things in LPC1343 basic development board

I have finished my LPC1343 basic development board,just based on specs from datasheet and some referred from microbuilders.eu. I'm unsure if the board design is good or not so I've attached my ...
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2 votes
1 answer
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LPC1788 external interrupt with CMSIS

There was a wide GPIO functions in the CMSIS initial versions which made easy setting and initialization of interrupts,like: ...
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2 votes
1 answer
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differences between privileged mode and unprivileged mode in the RTX RTOS

As i said in the title what's differences between privileged mode and unprivileged mode in the RTX RTOS? And why in privileged mode threads has allowed full access to the cortex M processor?
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2 votes
1 answer
2k views

practical use of NMI in Cortex-M3

So some Cortex-M3 CPUs (and most other small CPUs as well) have a non maskable interrupt. I know what the NMI does, but I don't quite understand why I ever would want to use one. I'm looking for ...
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11 votes
1 answer
9k views

Storing a secure key in an embedded device's memory

I am working on an embedded device which send/receive data and stored them in ciphertext mode (encrypted mode). Now what's best approach for storing keys (I used ARM CORTEX M series MCU)? 1-Storing ...
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ATSAM3N Cortex-M3 RAM Bit Banding

If i do not use Bit Banding feature on ATSAM3N, this region, it will used by the compiler for the program? Or it will stay unused? What if my program, randomly (by itself) should need to assign and ...
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