Questions tagged [arm]

32-bit microcontroller IP. The ARM company which designs the ARM cores doesn't make controllers itself, but licences the IP to other manufacturers. ARM is the leading 32-bit controller and is available from tens of suppliers.

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Why operations on float variable are performed on a double? STM32F401RE, MDK-ARM v5

I am debugging a simple line of code: float temp_f; ... ... temp_f= temperature[0] +(temperature[1] >> 5)*0.125; that is assembled into ...
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Understanding difference between Interrupt Address and interrupt vector address

In my undergrads, I was taught 8051 and in interrupts my professor had said that on interrupt SP points to the address that is hardcoded and Program goes to excute those instructions. But in between ...
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GNU ARM Eclipse - flash and run without debug

I have successfully installed and configured Eclipse for ARM development according to this excellent tutorial: http://gnuarmeclipse.github.io/ Almost all the tutorials (including the one above) I ...
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1answer
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Implement cryptography algorithms in an ARM microcontroller

Assume a situation in which you want do some encryption procedures in your ARM microcontroller. (Receive a file, encrypt with 3DES and some hash functions and returning it, for example.) As far as I ...
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Could an ARM (ARM7TDMI) Branch instruction take 6 cycles?

I have found an ARM Branch instruction appears to take 6 cycles to run on an ARM7TDMI processor. It seems it shouldn't be happening because in all references I've found, an ARM7TDMI branch instruction ...
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ARM microcontroller, where to begin [closed]

I had previously worked on Arduino but I think it was very simplified for the users. Now, I want to learn properly. I decided to begin learning ARM microcontroller. So, I bought LPC1114 DIP because I ...
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4answers
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OpenOCD child process termination: Wrong device detected

Setup I have an STM32F103C8T6 minimal eval board (see STM32F103C8T6). And I'm using an ST link like the picture below. I installed System Workbench for Eclipse. I created my own project (C++, Empty ...
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1answer
567 views

Getting started with Qualcomm reference designs

I am looking to get started with Qualcomm Reference Designs. I am partly inspired by this article: "Start Your Own Smartphone Company for $1,000". I have an application that I would like to be able ...
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1answer
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STM32 GPIO Configuration

I am trying to figure out some online resource to figure out how to configure the GPIO Registers on an STM32F4 Cortex M4 board. I only have examples for the Cortex M4 ...
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ARM Linux and UBoot - Can I make a read-only MTD writable?

I have several embedded Linux devices installed at customer sites. We have an updated Linux kernel we are prepared to deploy to these devices. The problem is that on these devices, the U-Boot ...
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Program only runs when debugging in GDB - using Open OCD and Olimex arm-usb-ocd-h jtag to program at91sam3su

I'm trying to make my Atmel at91sam3u cortex-m3 arm chip make an LED blink. I have a Olimex ARM-USB-OCD-H jtag programmer, and I'm using Open OCD running on OS X to program my chip. I'm using the ...
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How does the BSRR register work?

On the GPIOs of some ARM-based microcontrollers, you are given a register BSRR which you can write to to perform atomic changes in a ports output register. For ...
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1answer
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Why don’t most RISC ISAs write integer MULH/MUL or DIV/REM to two general-purpose registers? [closed]

Most hardware multiplication and division algorithms can compute the high and low words of a product of two integers, or both the quotient and remainder of the division of two integers, at the same ...
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How many layers at least for proper DDR3 fanout and routing?

I'm working on a project and have been banging my head against the wall for the past couple of weeks with the DDR3 fanout and wiring. I'm trying to keep the cost to the minimum, so I'm using the most ...
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2answers
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STM32F4 Discovery + Mac OS X + GCC + OpenOCD + Eclipse

I'm interested in buying an STM32F4 Discovery from ST Microelectronics. I'm using Mac OS X, 10.8 and would like to use a toolchain including GCC OpenOCD for debugging Eclipse IDE / IntelliJ IDEA ...
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2answers
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memcpy issue in ARMcc

I am facing an issue of bytes being copied in a reverse order when I compile code using ARMCC. For example : short int dest; short int src = 0x0010; memcpy(&dest,&src,sizeof(short int)); The ...
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1answer
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How can I make it so that customers who buy my arm based product can easily update the firmware?

I'm building an arm-based (stm32F7) hardware device which will have a USB port. I would like to be able to update the firmware and distribute it such that customers with my device can easily install ...
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518 views

CAN connection help needed

I bought the IAR Kickstarter kit to work with the SM470R1B1M-HT (Texas Instruments) microcontroller. I would like to implement CAN communication between the microcontroller and a PC. I need to send ...
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2answers
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Can Tiva C run code from SRAM?

All I know is that although Cortex-M3/4 micros are Harvard architecture, they can run code from RAM, at least some implementations can (like STM32F4). Can Tiva C series microcontrollers execute from ...
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1answer
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Basic OS definitions and implementations

The Rowley Crossworks package (includes compiler, IDE, debugging interface, etc.) also includes something called the Crossworks Tasking Library (CTL). From their website: CrossWorks Tasking Library,...
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Installing a bootloader on an ARM Microcontroller

I have purchased this LPC1788FBD144,551 MCU and this LPC1313FBD48/01,15 MCU and I want to install a bootloader in assembly on them which can call a function in C. How can I install the bootloader on ...
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970 views

What “bus turnaround” delay should my PSRAM have?

I have a PSRAM driven by an STM32. One of the timing options for the STM32 is the bus turnaround FSMC_BusTurnAroundDuration. The ARM reference manual (see page 1250)...
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8-pin JTAG for Marvell Sheeva board

I am looking for different option of interfacing to the JTAG port on a PogoPlug board. I have found the picture below which has silkscreen (my board doesn't), I have used JTAG before, but it was built ...
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1answer
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Proper way to wait N cycles in ARM Cortex-M4

After enabling a clock for a certain port you have to wait 4 cycles for the clock to finish initializing. How can one wait for N cycles the proper way? In my code I used this: ...
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What is the ARM 32 bit MCU with the fastest ADC? [closed]

I have been trying to find and answer, but it is remarkably tedious and difficult trawling through manufacturers data sheets. The best so far is 12 bit at 2MSPS
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1answer
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How to add memory to an ARM Cortex Microcontroller

I am looking into a design that would use the ARM Cortex M4F core but am just the software engineer for the project. The EE tells me that there will be an 64 MByte sdram memory module connected to the ...
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Electrical reset to a SIM card

I have a SIM card reader connected to an ARM, and I'm trying to get the SIM to send an Answer To Reset (ATR) and to get the reader to capture it. As I understand, an ATR is sent after an "electrical ...
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3answers
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LPC2131 problem reading IO pins

I need to read a value from a DIP switch. It is connected to ports P1.16 till P1.21. I use following code: to initialize: ...
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1answer
201 views

Features to include on a new embedded Linux board to make development and debug easier?

At my work we're planning on developing a new ARM based embedded Linux board. I want to give the hardware guys some guidance on features they could add that would make the software development easier. ...
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How is the code written in ARM7 compatible with ARM9?

I'm studying ARM families, In the above image, it is written that the code by supported ARM7 can be migrated to ARM9 and others. ARM7 uses the Von-Neumann architecture (single bus for data and ...
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5answers
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STM32 cannot reach individual registers and pins as PIC

I used to work with PIC and now I need to use STM32 chip. I was using HAL library but it gave me some problems so now I want to use it without HAL_Library. There are some questions I could not get any ...
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Why is there a system controller and a microcontroller in the same FPGA?

I am starting to dig into the FPGA world. While exploring the FPGA SmartFusion2 architecture I found out that there is a microcontroller (ARM Cortex-M3) and at the same time a system controller. Why ...
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DDR3 routing: swapping data wires

Is it possible to swap wires in data bus between CPU and DDR3 x16 memory for routing optimization? So, for data lines depends on the correct order? For example connect DQ0 on CPU to DQ1 on memory ...
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3answers
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Do I need OS for ARM Cortex-M0(3)?

I'm a developer of control devices for switch mode power supplies which need to generate a PWM signal(s) with a frequencies about 100 kHz, measure analog signals, communicate vie USART, make ...
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1answer
534 views

ARM Development [closed]

I an new to using micro controllers .Recently, I have seen the ARM being talked about. How different is ARM -Cortex development than normal Arduinos? I have used a PSOC recently, which does use an ...
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3answers
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LPC2148 ADC problem with voltage divider for battery

edit: solution found with our new board revision; outside of careless mistakes, buffering the signal with an op amp seems to have resolved the issue (as suggested by Joshua below). I am working with ...
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1answer
609 views

Should I define default register values in start up code?

It has come to my attention that some ARM programmers set some CPU registers with values that are the same default values of the register on microcontroller reset. For example: the default value of <...
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3answers
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High resolution system timer in STM32

I have some software running on an STM32F103 (I'd also like to be able to use the F4) where I'd like to be able to 'timestamp' events (such as interrupts on external pins) to the nearest microsecond (...
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2answers
752 views

MCU RAM - Why accessing RAM across the boundary causes Bus Fault?

My question is best explained by an example. There's an evaluation kit from Infineon that uses ARM Cortex-M4 and has a total of 80 kB of RAM. There is also 512 kB of Flash memory. [However, it seems ...
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932 views

ARM Instruction set

I am trying to enter into the world of ARM and one thing I come across very often is that ARM processors support ARM and Thumb instruction set. So it means compiler will use Thumb Instructions which ...
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3answers
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Basic timings with an STM32

I am looking to make very basic timings on an STM32. For example, I would like to program my STM32 to output bytes on the UART for 1 minute. What clock/timer should I use? Looking through the ...
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2answers
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Where can I find the in-depth LPC2132 datasheet?

I have searched high and low on Google for the user manual about the LPC2132 ARM chip. So far, all I have come up with is the ARM7TDMI manual and a short (41 pages) overview of the LPC2132 chip. ...
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What are the implications of a ROMLESS device?

I was looking through the microcontrollers area of Digikey and I noticed a device that i'm interested in although there is the description of "ROMLESS" in the program memory type. http://www.digikey....
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Choosing the right microcontroller [closed]

How do you choose a micro-controller for your project? My hardware requirements are : I2c SPI ADC channels SMD package 3.3V operating voltage A few GPIOs. There are so many microcontrollers ...
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2answers
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Why does __libc_init_array cause an exception?

After a long time trying to debug why my simple blinky code for my STM32F446RE microcontroller was not working i discovered a line in the bootup assembly file that i was linking to it which was ...
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3answers
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Using an MCU with built-in CAN controller vs. external CAN controller

I'm planning to use the Atmel ATSAMC21J18A microcontroller in an automation project which has a built-in CAN controller. The CAN bus network may contain 32 devices, each generating data packets in 1 ...
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3answers
940 views

Does lack of MMU make any difference for applications?

Generic Linux can't be run on Cortex M3 because Cortex M3 has no MMU. Okay, there're special versions of Linux that can run there. The problem is I don't quite get how this affects application ...
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Impedance of microcontroller pins with no power supplied?

I have a serial flash chip connected to an ARM microcontroller (AT91SAM9G20). I'd like to be able to program the serial flash after both chips are soldered on to the PCB. For each of the serial flash ...
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1answer
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Is JTAG the standard way to program ARM processors?

Some electrical engineer once told me, that each ARM M3 processor can be flashed the same way, no matter which manufacturer it came from. I suppose he meant using JTAG, or is there another way? Btw,...
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Differences in using c user-defined functions on PC and on ARM

I am new to programming in c and to ARM also, so forgive me silly question. I would like to find answer on the net rather than to bother you, but there is not many materials in the web. I am using ...

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