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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476 views

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 ...
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ARM Power/Exponential Function

I'm trying to code an exponential function for use on a PWM signal. My question is, does anyone know how to do a power function on an ARM cortex-M (STM32F4 in this case, which has an FPU) ...
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137 views

Connecting with only JTAG

I've been wanting try out new microcontrollers and microprocessors other than the very mainstream Arduino and similar. So I want to start by making a inexpensive test board with a minimal test of ...
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2answers
4k views

Use Raspberry Pi Gpio Header as Memory Mapped Interface

Raspberry Pi is really an interesting device for its support of so many features in such a small and simple formfactor. If the GPIO expansion header can be accessed in the same way as a normal memory-...
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2answers
925 views

Sorting of data from instructions ( ARM I-cache and D-cache )

Some ARM cores like the ARM9 family of cores have a Harvard Architecture, at least at the cache level. That is they access two seperate caches, an I-cache for instructions and a D-cache for data ( ...
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3answers
281 views

PSRAM: First operation bogus, later operations fine

I have a PSRAM driven by an STM32F2 in the default asynchronous mode. The PSRAM works fine except for the very first read or write operation. After the first read or write operation (which produces ...
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3answers
2k views

Is the GPIO speed involved in the baud rate of my USART?

I am working with am ARM Cortex M3 where two GPIO pins are configured as Alternate Function for use as USART pins. When setting the pins as Alternate Function, I have to set the Output Speed of those ...
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2answers
204 views

Cortex M7 goes to HardFault immediately after reset

I am using the ATSAME70Q21 processor with a Cortex-M7 CPU. My development environment is Atmel Studio 7. I am using the SAME70 XPlained demo board. I am creating some code in assembly language. As ...
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2answers
222 views

ARM Cortex cores with peripherals, basic requirements

I've been reading a lot of stuff about using ARM tool chain to build applications for different microcontrollers including ARM cores. Right now, I've been using the fairly easy route with Atmel Studio ...
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2answers
111 views

Am I using ARM 7 LPC21xx ADC register correctly?

Why is my OVERUN bit 1 when ADC function is placed inside a timer interrupt routine? As per the User Manual Page 306, the OVERUN bit is 1 in burst mode if the results of one or more conversions ...
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1answer
604 views

Unused GPIO pins shall be configured as pull up or pull down [closed]

I have recently started working on Embedded Systems. I am configuring GPIO pins for MCU. But I'm bit confuzed whether I should configure them pull up or pull down. Is there any configuration rule to ...
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2answers
793 views

Detecting JTAG pinout

I want identify JTAG pinout on the target board, using the JTAGenum tool. I have read the JTAGenum code, and want to clarify a few point about user configuration. JTAGenum can identify 4 mandatory ...
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1answer
893 views

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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544 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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1answer
7k views

How many cycles does an ARM Cortex M0 use to multiply floats?

On an ARM cortex m0+: How many cycles does it take to perform multiplication of single precision floats and store them into a float? i.e. x = a*b; Where x, a, and b are single precision IEEE 754 ...
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Why are ARM9 and ARM11 processors still used when the Cortex-A5 is more efficient? [closed]

Many consumer devices that require a low-power processor capable of running for several days to a few weeks on a charge still use ARM9 or ARM11 processors. However, the ARM Cortex-A5 is more powerful ...
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NXP LPC 4330 Microcontroller starts up very hot and sometimes doesn't start up

EDIT 3 The correct solution is shown below, in TurboJ's answer in fact, this exact issue was mentioned in the LPC4300 errata ES_LPC43x0: EDIT: Nope, sorry false alarm. The new board started doing the ...
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6k views

Why is the USART receiver pin configured as “input floating”?

Reading through this good tutorial on setting up the USART on an STM32, the Bus Setup paragraph says that the receiver pin (Rx) should be set as input floating. I would have thought that because the ...
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7k views

STM32, Keil and *** error 65: access violation at 0x60000000 : no 'write' permission

I tried to run LCD software in Keil for STM32, but I got *** error 65: access violation at 0x60000000 : no 'write' permission Do you know how to solve that error ...
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1answer
140 views

Any ideas on what to do with a board that condition is unknown?

I got given a Cirrus Logic EDB7209-2B.0 with LCD Display. It powers up(the power LED lights up and there is power on the board accessing the ARM CPU) but i'm unsure on what to do with it has anyone ...
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2answers
932 views

STM32 software IDE [closed]

After a two year experience of ATMEL's SAM mcu I decided to move on STM32 microcontrollers. I choosed to begin with STM32F410RB. After a lot search on the internet I found two free IDE, Atollic ...
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1answer
412 views

Timer problem on STM32F7 - erratic behavior

First off I'm a complete n00b and just getting started with STM32. I'm encountering some weird behavior while setting up TIM1 and also using external interrupt EXTI3. I'm attempting to measure a low ...
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2answers
6k views

Using Visual Studio as IDE for mbed developement

I am aware that is has been looked at / done in the past, but I was wondering if there is anyone who has experience / understands how I could use Visual Studio 2015 Professional to develop mbed code ...
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1answer
399 views

ARM Processor board and Programming

I am trying to develop an ARM development board using ATSAM3U4C with a 96 MHz clock, a few LEDs and a button for external interrupt. Shown below is a little circuit that I have put in place. Using ...
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1answer
2k views

What do these OpenOCD CPU states mean?

Here is what the documentation has to say: ...
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2answers
288 views

Best practicce to refresh data on LCD

I am currently reading value from ADC and displaying on LCD screen. The ADC is supported by DMA. Now my system has 5 menus seen on LCD (Voltage, Current, Resistance, Settings). 3 of them should ...
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1answer
3k views

TXE bit not reset in USART communication

I am programming an STM32F2 Cortex M3 chip (reference manual here). Specifically, I want to transmit bits through the USART. Reading pages 620 and following, I understand that the ...
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1answer
176 views

Can't run code in Keil for STM32L433RCT6P on NUCLEO-L433RC-P

Recently at Embedded World 2018 in Nuremberg I got, for free, NUCLEO-L433RC-P with STM32L433RCT6P chip onboard. I want to broaden my knowledge in STM32 chips. Before, I did simple stuf on STM32F4. ...
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2answers
71 views

Why is the cache size identification register on ARM CPUs accessible from privileged modes only?

Is there any logical decision making behind this, to my understanding it exposes only the same information as CPUID instruction from x86 so why is it only made accessible to EL1? Is this in some way ...
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1answer
86 views

ADC Burst mode in LPC2119 not working

I have been trying to work with ADC using ARM 7 LPC 2119 in burst mode however this functionality is not working. My code is as follows: ...
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1answer
7k views

STM32F4 HAL Library Button Interrupt

I'm trying to toggle built in LED with external interrupt instead of while loop. Probably I'm doing something wrong with EXTI functions. Can you help me to fix it? ...
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3answers
232 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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2answers
582 views

NVIC on ARM CPUs

Can we look at NVIC peripheral on ARM CPUs like some sort of thread? Main application is executing, and at the same time NVIC peripheral doing her own work? Or all of that is single thread application....
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1answer
1k views

How to use level-triggered interrupts with STM32F1xx?

I'm getting conflicting info on whether I can use level-triggered (as opposed to edge-triggered) interrupts with the STM32F1xx microcontroller. In ST's CMSIS-compliant Standard Peripheral Libraries, ...
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1answer
722 views

How to connect the power for VREFSD pin and anlog pin in STM32F3273 (ARM Cortex-M4) for SDADC application?

I have an analog amplifier which is powered at single-supply power and have an analog ground of 1.25V. I want to perform sdadc for my analog output. I am using STM32F373 (48pins), which is an ARM ...
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1answer
972 views

What is Platform Bus in Embedded Systems?

I would want to know what is the Platform bus in SoC . I have seen some device driver implementation in Linux kernel where drivers are registered with platform bus or rather should i say these all ...
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1answer
623 views

Reducing chip count for an ARM embedded system

It seems like a lot of devices use an ARM SoC + a RAM chip + a flash storage chip. In applications that are very space-constrained, such as ChromeCast dongles, micro drones, or wristbands, it would be ...
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1answer
834 views

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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1answer
142 views

Is there any single-board computer/system-on-a-chip with good documentation for developing bare metal? [closed]

I always wanted to develop my own crappy operating system, but the many weird legacy quirks of the x86/PC platform kept me from doing so (e.g. real vs protected mode, only low resolutions available in ...
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1answer
223 views

Combining the outputs of multiple SPI devices

I have a project that has an array of digital microphones whose output I would like to perform some fancy signal processing on, using a high-powered ARM micro-processor. I like the idea of using ...
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1answer
979 views

Running code from RAM and not using FLASH (ARM)

I have an application for my ARM7 which is usually burned to FLASH, and then on execution it is copied to RAM (to run a little faster). But I remember that my professor once said that I should run my ...
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1answer
1k views

Changing flash latency from 0 to 1 even with enabled prefetch slows execution on STM32

I have put all clock configuration to its default state, so an internal oscillator is running at 8 mhz. I have a delay loop using inline assembly as follows: ...
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2answers
512 views

What should I know if I want to move from microcontrollers to microprocessors? [closed]

I'm familiar with using microcontrollers, both with frameworks like Arduino and natively (PIC / AVR). I'm also familiar with the general architecture of embedded systems, in so much as I know you have ...
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2answers
245 views

Task switching on Cortext-M3 crashes after IRQ

I've used an exokernel model for my ARM OS. When a task wants to read from a UART it calls a library function, which, if there's no data, makes a SVC call to block the task (which causes the kernel to ...
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2answers
975 views

STM32 and uCOS+uGUI

Can I use STM32F103VCT6 with uCOSII2.91 and uCGUI3.90A ? Because from datasheet I saw the flash memory of STM32F103VCT6 is 256Kb and the result of compiling uCOSII2.91 and uCGUI3.90A is 689K I'm using ...
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1answer
272 views

API portability for ARM Cortex (Xilinx Zynq 7000) with PowerPC (Xilinx Virtex 4)

Are the APIs(or tools) used by "PowerPC Hard Macro" to integrate with Virtex 4 similar in the case of ARM Cortex with Artix 7(in Zynq)? Ideally it would seem so since Xilinx would keep it that way ...
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1answer
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uCLinux footprint breakdown?

Another question I have asked made me ask this question.. The previous question was about fitting Linux into Cortex M3. A few well answers proved that it is not feasible. SOmebody suggested ucLinux. I ...
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161 views

Weird problem on STM32 ADC with Interleaved Mode

I am sampling a signal on the STM32F3 Discovery board (stm32f303vct6) with two ADCs working in interleaved mode. It works great with a 200kHz 1V sine wave. But when I apply 10kHz 100mV sine wave, I ...
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73 views

How to implement critical sections on ARM Cortex A9 for GCC, no OS? [duplicate]

I am porting some legacy code from an ARM926 core to CortexA9. This code is baremetal and does not include an OS or standard libraries, all custom. I am having a failure that appears to be related ...
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2answers
2k views

Are there 8 bit ARM processors?

Is there anything below 32-bits for an ARM processor? I was wondering if there is or ever was an 8-bit ARM processor. I've searched but not seen any and so it seems that ARM processors are either 32 ...