Questions tagged [avr]

AVR is the family of microcontrollers used in Arduino boards.

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Arduino EEPROM retains old data after flashing with a new program

I have a custom 5V 16Mhz Arduino Uno (a breadboard Uno of sorts) that runs the grbl firmware. After the initial flashing I can see all the settings (through the serial monitor) and everything works. ...
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2answers
5k views

Since double and float represent the same data type (usually), which is preferable?

It looks like on ATMega based boards, float and double are equivalent 32-bit (4-byte) data types. However, on the Arduino Due, doubles are 64-bit (8-byte) where floats are 32-bit (4-byte), same as ...
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1answer
889 views

Atmega168 Watchdog timer

I'm trying to use the watchdog timer to prevent the atmel from being stuck in a loop. Right now, I have the watchdog timer in System Reset Mode, with a 8sec timer. I reset the timer in every loop ...
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1answer
1k views

Custom Arduino library problem

I have made my custom serial(UART) library. So I made uart.h and uart.cpp files as following. uart.h #ifndef UART_H #define UART_H #include <avr/io.h> #include <stdlib.h> //creating ...
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1answer
4k views

How to create delays in AVR assembly language

Hi i'm new to AVR assembly language so i was trying to get delay function to create 1 ms , 100us, and 1us delays to do that i need to figure out what to replace nop's with below here (mainboard ...
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1answer
58 views

3-instruction remote machine coding Arduino Atmel chip over a serial line from a tethered (host) PC

I'm trying to write a program for AVR Atmel 328 chip on Arduino Nano board that will allow me to send machine code instructions to the chip over a serial line, run/execute them on the chip, and ...
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2answers
1k views

Change the fuses of an Arduino Uno (can an Arduino Uno change its own fuses?)

For now, I'm using an Arduino Uno alone including its 328p (no other external chip to program). I would like to change its fuses to internal 8 Mhz clock (because then I'll move the 328p out of the ...
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1answer
339 views

Assembly for loop repeating 2 times when it's only suppose to do it once

I'm programming an Arduino Nano so I belive that this question should be qualified for this SE. I am trying to dim up an LED using a for loop in AVR assembly. My problem is that the cycle is ...
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1answer
2k views

How does DDRD |= _BV(PD2) differ from digitalWrite(2,HIGH)?

I'm attempting to copycat the work of Louis Frigon's Toyota Aux Enabler. I have (with a lot of help on this site) managed to begin capturing and understanding messages on the AVC-LAN bus, but I can't ...
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2answers
1k views

programming arduino in pure c

I'm trying to flash pure c-code to arduino Mega2560 board from linux using avr-gcc & avrdude. Compilation is done , now trying to flash using avr-dude, getting error as "avrdude: stk500_recv(): ...
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1answer
1k views

Atmega328p programming with Arduino libraries

I'm trying to use the serial communication to work between a naked AVR Atmega328p and a computer (OS X and Linux Ubuntu). I can program the atmega (using a pololu programmer), I make it blink a LED ...
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1answer
2k views

Uploading .hex to ATTiny13 using Arduino

I would like to upload a .hex to ATTiny13V (or '13A) using Arduino Uno R3. I think I know everything to do, but ATTiny13 ISP support and Arduino IDE is a bit search-and-find, and I have some grey-...
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1answer
362 views

In UART, what mechanism sets the “new data received” flag back to 0?

I was reading documentation on UART on AVR and it looks simple: when a flag (bit RXC0 of register UCSR0A) is set to 1, it means the micro controller has new data for you, and you read this from ...
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1answer
507 views

Cannot enter programming mode on Arduino Uno

I have an Arduino Uno that I've been programming with an AVR Dragon through Atmel Studio 7. I did two things in close proximity, and I'm not entire sure which action is the culprit. I tried using the ...
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0answers
43 views

Attiny85 uploading error

I am getting an error while trying to upload programs to the Attiny85 through a USBTinyISP programmer, found here. Unfortunately, it isn't working. Following this tutorial for connecting the board and ...
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0answers
519 views

Is it possible to put ATtiny85 to sleep while using TinywireS?

I have an arduino uno as the master I2C device talking to an ATtiny85 as the slave. What I want to do is have the Attiny85 receive a message from the UNO to tell it to power off which will then ...
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0answers
1k views

Does Proteus simulate external interrupts properly using Arduino? I can't get them to work

I am trying to simulate an interrupt with an Arduino Uno in Proteus. This is the simple test code that I'm using: void introutine() { digitalWrite(13,HIGH); } void setup() { pinMode(13,OUTPUT); ...
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97 views

SPI Interface between Arduino UNO and EVK1100 [closed]

I'm using Arduino Uno board as master and AVR32UC3A0512 as slave. I've written code for arduino using SPI.h library, and Atmel Studio 6.2 using spi.h. I'm sending data from arduino to atmel i.e from ...
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0answers
484 views

Arduino Due - Multiple Serial Lines

I'm trying to interface with a serial device utilizing Serial1 (pins 18,19) on the Arduino Due. The normal serial port (Serial) is working just fine and is acting as a debug port at the moment - It's ...
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4answers
18k views

New to Arduino: Should I learn C, C++ or both (C & C++)?

From what i've researched here is my thoughts on both C++ I heard that you can create libraries using C++ in arduino. And you can use the Arduino IDE to do that stuff. Here is the proof http://...
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4answers
928 views

Float arithmetic vs. int arithmetic - is there any power penalty?

It is widely known that float arithmetic takes longer (that is, eats more cycles) than fixed-point (or integer, or bitwise arithmetic), and that surely is something to consider for speed- and time-...
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3answers
564 views

More speed from ATMEGA328 Internal Clock

I have a board that is designed and produced. It was designed to use an Atmega328 with the internal clock. There is no space on the board to place an external clock. After completing these and testing ...
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1answer
127 views

Problem with programming digispark ATtiny85 board with Arduino IDE

I have bought a Digispark ATtiny85 board to learn about that microcontroller. So I tried using internal register names in the code rather than using Arduino in built functions. I can get the board to ...
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2answers
815 views

How to read OC0A when in CTC (toggle) mode?

I have this code, which puts the Arduino into CTC mode with interrupts, and outputs a square wave on PD6 (OC0A): void setup_timer(double p_ms, double duty){ DDRD |= (1 << 6); // set pin 3 as ...
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2answers
2k views

Why we can wake Arduino Uno from sleep using only pin 2?

Can we use other pin as an interrupt to wake Arduino Uno from sleep ?
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3answers
708 views

Arduino UNO USART problems

I need to send 6 bytes value from Arduino UNO to the actuator using serial port in order to make it extends. I have added a button to send the data. For example, 0 20 1 1 0 0. The communication ...
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4answers
2k views

Reset and Remove Arduino ATmega328P?

So I have 2 Arduinos, and im wanting to remove the chip from one and reset it to like it came from the factory and then breadboard it and attempt to program it using an AVR programmer (Or maybe an ...
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1answer
3k views

AVR timer overflow interrupt not working

My problem is an interrupt service routine (ISR) that seemingly never executes! Here's some info on my set up: I am flashing an avr attiny85. I have the bare bones of a project set up so far with ...
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2answers
3k views

AVR (Arduino Uno) Serial.print and Serial.println only printing 1 or 2 chars

I first used the Arduino IDE but now I'm using PlatformIO which is awesome. But I have some big trouble with Serial.print() and Serial.println(). To show this error I have the following example code: ...
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4answers
1k views

How to program a CLK signal and its inverse with Arduino/AVR

Is it possible to simultaneously output a clock signal and it's inverse using the timer register(s)? I'm using the following code in arduino to output a 1MHz signal on OC1A: //Use Timer/Counter1 to ...
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2answers
270 views

Use ATTiny as a battery-backed RAM?

So, I found an interesting article the other day, and I'm trying to build a project that could benefit from a battery-backed memory (no wear limits, but keeps data over power cycling). The article ...
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2answers
706 views

ATmega328p - ISC00 with INT1?

I was reading about external interrupts using the ATmega328p, and I saw in the chip datasheet under the paragraph "Bits 3:2 – ISC1n: Interrupt Sense Control 1 [n = 1:0]" the following table: Value | ...
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1answer
59 views

A confusion with setting timers

I was reading a tutorial on timers. My aim is to generate 16MHz pulse output from the pin 8. Here is the code I modified from the tutorial (I use Arduino's ATmega328P): #include <avr/io.h> #...
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1answer
306 views

Porting Arduino code to AVR/C++ input not working?

So. I'm trying to read an input on the Arduino Nano using C++/AVR/Eclipse instead of the regular arduino IDE. The code below is working in the arduino IDE void setup() { // put your setup code here,...
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1answer
109 views

How to add two assembly arrays in arduino

Hey guys what I'm trying to do is to sum two arrays and return a new array; for example if given uint8_t a[] = {2, 4, 6}; uint8_t b[] = {1, 2, 3}; I should get { 3, 6, 9} What I'm trying to do is ...
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1answer
199 views

Assign an interrupt to any pin of the atmega328 microcontroller

I need to record the appearance of a signal from the sensor on the PD0 pin. This is the first time in my life that I want to use an interrupt for this. With your help, I configured the sketch for my ...
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1answer
41 views

Is it possible my ATMega is burnt due to bad wiring?

While working on a project I tried sending data from my Arduino NANO to ATMega64 placed on AREXX Robot arm PCB via TXD/RXD. After plugging in VCC, GND, TXD and RXD to UART socket it didn't work so I ...
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1answer
656 views

AVR & PIC 8-bit Microcontrollers - Can you add: external flash memory, external RAM, video & audio output, more address busses?

so I was planning on creating a mini PC out of basic ICs and 8-bit microcontrollers such as ATTinys and/or PICs and I have several questions regarding those: Can you add external RAM, say with SRAM, ...
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2answers
53 views

about receiving float on matlab from ATmega32 Avr

****i am using ATmega32 to send float and want to receive it on matlab,i send 4.85 from ATmega32 but on matlab i receive 4.260233679216239e-31...can any one help me..thanks in advance** ** //...
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1answer
96 views

Arduino Timer0 Piggyback

As described here https://learn.adafruit.com/multi-tasking-the-arduino-part-2/timers I use timer 0 to get my own timer with a milliseconds resolution. It is setup like this: void setup (void) { ...
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2answers
253 views

About ATmega32 event system

From my reading on internet i found that the Event system allows peripherals to trigger each other without involving the CPU...does the event system is software or hardware?also does ATmega32 support ...
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1answer
150 views

Force TCNT to stay below OCRxA on ATmega328P

I'm using a timer and the TIMERx_COMPA ISR to generate a signal in "the background". This ISR is triggered when the timer reaches a certain value (OCRxA), which in turn can be changed by the user. ...
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1answer
212 views

Trying to make sense of the coding style in Arduino libraries. (Particularly the Radiohead library)

I've been using the Arduino IDE for some time now, and I want to shift to coding for the bare AVR microcontroller. So I wanted to begin by porting required arduino libraries to C/C++. I started with ...
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2answers
2k views

Arduino analogWrite source code explanation

The source code for the analogWrite function looks like this: void analogWrite(uint8_t pin, int val) { ... sbi(TCCRnA, COM0x); OCRnx = val; ... } Where n is which timer (0, 1, 2...) ...
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2answers
165 views

How do I use an ATMega 328 (not P) chip with an Arduino board?

I just burned the bootloader on an ATMega328 chip and then I put in on the Arduino board. But when I try to upload a program to it, it says programmer not in sync and programmer not responding. For ...
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3answers
770 views

Problem with transmitting 2 byte data in correct way

I'm using Atmel Studio with Atmega328P. I'm trying to send the decimal number 876 continuously from the micro-controller. This was just to learn. To send 876 I need two bytes which is: 0x036C = ...
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2answers
755 views

From Wiring to pure C

I'm using the Teensy 2.0 (atmega32u4) and decided to switch from Arduino IDE with Wiring to pure C. I think it's much more useful to master programming microcontrollers on that level. Wiring seems to ...
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1answer
66 views

Complete Bread board arduino

I bought a ATmega328 microcontroller and burn the bootloader. Now I want to upload code directly from pc to the microcontroller on bread board. I have max232 ic for the communication but I recently ...
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1answer
257 views

How to set PC (Program Counter) register to another function (for scheduler)

I am trying to implement a scheduler for Arduino Mega 2560. I think I lack understanding of how to set the PC register to another instruction. Here is my simple approach so far: void dummy(){ ...
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1answer
159 views

about how to share one External serial EEprom using two microcontrollers?

strong texti have Vector nav100 IMU sensor that sends data serially UART.I want to receive data from it using ATmega32 and then store data in AT24c1024 EEprom using I2C,then using another ATmega32 to ...