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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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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777 views

Moving code from an ARM M0+ to an ARM M4, what changes?

Say I have a very simple program that functions perfectly fine on a ARM Cortex M0+ processor. How much will I need to change in order for it to work on an ARM Cortex M4 processor, assuming they are ...
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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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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
84 views

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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478 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 ...
4
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1answer
339 views

ARM Cortex M Power Consumption — Sleeping with Higher Clock Speeds vs. Lower Clock Speeds

I'm starting with Cortex M processors, but I have lots of experience with 8bit MCUs. Say I have a buffer that needs to be updated every 5ms. There is an interrupt that goes every 5ms and the buffer ...
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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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Relationship between reset pins and SWD functions (ARM Cortex M0)

On many microcontrollers or other devices without JTAG/SWD functionality, there is a reset pin which when low unconditionally and asynchronously forces everything into a known state. On devices with ...
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1answer
176 views

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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Low priced universal USB ARM JTAG that works with a broad range of devices and SDK's?

Can someone recommend a reliable USB JTAG programmer/debugger for ARM processors, mostly Cortex-M3/M4, from a variety of manufactures like ST, TI, Atmel, and NXP, that will work with Keil, IAR, etc. (...
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788 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
3k views

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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1answer
3k views

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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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
5k views

Printf style debugging via SWD

Is it possible to send arbitrary messages (as with printf()) via SWD for debugging?
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1answer
197 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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4answers
2k views

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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3answers
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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
520 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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Laying out a 10-pin JTAG/SWD connector on a final design

I'm designing a board with an ARM microcontroller on it (LPC1347FBD48) and I want to include a 10 pin jtag/swd connector, as is standard, for in-circuit debugging of my final design. Here is the ...
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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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952 views

Nested Vectored Interrupt Controller (NVIC) - Why is it “nested” and “vectored”?

In ARM microcontrollers there is an peripheral called NVIC (Nested Vectored Interrupt Controller). What does the "nested" and "vectored" part refer to, or why is it "nested" and "vectored"?
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1answer
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Programming pattern to generate VGA signal with micro-controller?

I want to generate VGA signal with micro-controller (like TI Tiva ARM which runs at 90/120Mhz speed). I'm not sure how to make accurate timings with micro-controller. Which programming pattern I need ...
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2answers
6k views

stm32F103C8xx big or small endian?

is there a reason for stm32F103C8xx to be big endian and is it possible to change to little endian? I have a 16bit oriented addressing scheme that I need to send over wire and other side expects MSB ...
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1answer
522 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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687 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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900 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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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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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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3answers
217 views

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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3answers
874 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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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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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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3answers
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Comparison between uint8_t and String

I have a very fundamental question regarding string comparison.. I implemented a USART to PC with STM32L0 Nucleo board, and I can type something in terminal and receive it on the micro as follows: <...
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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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How fast can ARM Cortex M0s/M3s bit bang?

I have not yet used ARM Cortex uCs, only AVRs Firstly, how fast can they: Stream 1024+ bits (serially, from bytes in RAM) out of a pin, with no pauses/jitter Stream 1024+ bytes (parallel, from RAM) ...
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234 views

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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1answer
964 views

Which ARM Cortex M chips allow for execution from RAM?

I've been playing around with writing operating system-like software, mostly as a self learning experience. I've been doing this on the Atmel AVR processor, since it's simple enough for me to ...
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IAR ARM Place const symbols in flash

I have the following flash section defined in my linker file: keep { section .SomeConst }; place at address mem: 0x0003F800 { readonly section .SomeConst }; In ...
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Can I Relocate Code on ARM Microcontroller?

I am working on a project which includes an ARM microcontroller. At runtime, I want to load code from an SD card into program flash and then execute that code. My question is, since ARM code seems to ...
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Do I need a license to design IP cores with AXI interfaces?

Many IP cores especially from Xilinx have an AXI interface from ARM. (AXI, AXI-Lite, AXI-Stream, APB, ... are parts of AMBA - ARM's bus architecture). The AXI interface standard is free for download (...
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1answer
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FPU vs. Fixed point multiplication/division speed

Is fixed point multiplication/division still faster than floating point operations when a FPU is present? Is there any situations where this might change? For example under very heavy floating point ...