AVR is a 8- and 32-bit microcontroller core developed by Atmel. AVR was chosen as microcontroller for the popular Arduino SBCs.

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AVR - Simple(st) serial port programmer

As I'm just getting started with learning anything about microcontrollers, I started from making a very, very simple LPT port programmer (...I think it was just about 4 resistors). It worked well with ...
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Uart serial communication failing to echo back Atmega16a

I am new to the avr (8bit uc) and recently I ran into a problem using serial communication (uart) with PC. Microcontroller fails to responsd in putty terminal where it should echo back whatever I ...
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How to Monitoring the lines between an Atmega8 and a LCD using Atmega32

I have a device that it use an Atmega8 to send some data to a 2*8 character LCD. the LCD has 8 pins and the pins are as below from left to right: DB7 | DB6 | DB5 | DB4 | En(Clock) | RS | VDD | VFF I ...
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56 views

What are these unpopulated holes on the Arduino Leonardo?

None of the pinouts online mention these holes next to the power barrel and LEDs. Are they connected to anything?
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Recovering fuse bits Atmega128RFA1

I am using an ATmega128RFA1 for senior design. I ran the following avrdude command to set the appropriate fuse bits to use the external clock, however it failed and the high byte of the fuse bits was ...
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43 views

Setting port in main loop causes ISR to starve

The example code initializes an asynchronous timer that is fired every second sets two ports as outputs (PA4, PA6 - LEDs connected) the timer ISR toggles pin PA4 permanently sets pin PA6 to 1 in the ...
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96 views

Two different MCU , different output but none was right?

I write this simple code to check my new burner : #include<avr/io.h> void main(void) { DDRC = 0xFF; //high pins PORTC=0x00; while(1) { PORTC=0xFF; } } ...
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19 views

avrdude: ser_open(): can't open device “usb”: The system cannot find the file specified

I'm using an AVRISP mkII programmer to flash an Atmega 328p MCU. Not an Arduino, this is my design. I'm using avrdude which came with WinAVR. I don't have Atmel studio installed, and I'm using Windows ...
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45 views

MicroSD card SPI with ATmega32

I want to communicate with a microSD card with an ATmega32 using SPI. I make a simple SPI loopback, and it works fine. Now, how can I communicate with the microSD card to write and read simple bytes ...
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46 views

Low power strategy for dealing with spontainious bit flips durring sleep on AVR 8-bit?

I am designing a ATTINY-based circuit that is intended to run unattended for very long periods of time on a very small battery. The device spends almost all of its time in deep sleep, and only wakes ...
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425 views

WLCSP MCU's - what hardware is needed for programming these tiny chips?

I just received my DigiKey order of some Atmel ATTiny4 MCU's from DigiKey. I wanted to tinker with one of the smallest MCU's I could find, and this was one of them. It is, in fact, so small because ...
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Learning AVR XMEGA

I am trying to learn how to program the AVR XMEGA by using the XMEGA-A1 Xplained kit with a JTAGICE3 programmer. I am going through the Xmega Basics pdf (link). In one of the instructions I am told ...
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26 views

Is it possible to program AVR microcontrollers using USB-UART converter instead od USBasp?

Is it possible to program an AVR microcontroller (e.g. Atmega328P) using a USB-UART converter like this one: Instead of a usual USBasp ISP programmer: ? If yes, is the procedure the same as in ...
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36 views

ATmega PWM frequency resolution

I am using an ATmega328 for generating a PWM signal. But I need a specific frequency. So I tried to use "PWM Phase Correct" mode (mode 10) for Timer 1. It says, the TOP value should be ICR1. It ...
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Cant program my AVR kit (Atmega 8) [closed]

I have been using a AVR development board for a long time. I used this board for trying many programs and all worked fine. I am using HIDbootflash to burn and CVAVR to program. Now i am experiencing a ...
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56 views

Moving from Arduino to ARM - what should I be considering? [duplicate]

I have a ton of experience working with the Arduino, and I'll say I'm an intermediate in straight C++ AVR and PIC applications. I'm now working on a project on top of an Atmega1284P that is running ...
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29 views

AVR chip restarts when RX line connected to a USB-to-serial module

I have an ATmega644 connected to a USB-to-serial module. When I currently have the ATmega TX line connected through and the RX line connected via a switch as follows: simulate this circuit ...
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crystal oscillator and CSTRAY

Let assume I'm using atmega8-16pu and I want to connect a 16MHZ crystal oscillator with 20pF load capacitance. Now I need two capacitor connected to GND and the chip ( XTAL1/XTAL2 ) itself so I have ...
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29 views

Determine the correct capacitors value

what the right way to determine the correct capacitors value needed for a avr-chip with a crystal oscillator? Let say the crystal's load capacitance is: 20pF and i want to use: atmega8-16pu what ...
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18 views

Is it possible to use arduino uno programmer for other microcontrollers from avr? [migrated]

i got an arduino uno which i started to use with microc for avr to add more customisation. I am wondering if it is possible to use the arduino uno programmer to programm other microcontrollers from ...
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1answer
214 views

Can't modify global variables in interrupt, despite having declared them volatile

I can't seem to get my global variables (low, high) to change inside my interrupt, despite having declared them volatile. Below is my code. I find it strange that I can modify my global variable ...
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61 views

I wish to use ADSL protocol for my Project, can someone help me please? [closed]

I would like to use ADSL protocol for my application which involves Master-Slave communication between devices. I have done it with Ethernet(ENC28J60). I would like to now if it is possible to ...
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1answer
32 views

FXOS8700CQ - Arduino core I2C doesn't work, SoftI2C does

I use the Arduino core libraries in my latest project (ATMega328P MCU) I'm trying to talk to an FXOS8700CQ via I2C. Reading register 0x0D should return 0xC7. The typical Arduino Wire library method, ...
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34 views

ATXMega32D4 Two Wire Interface

Lately i have been using ATMega32A and ATMega324PA and learnt various coding techniques in AVR C programming. One such code i wrote is avr_twi.c for communicating with an I2C accelerometer Now i got ...
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66 views

1V output only when load is applied?

I'm working with the Teensy++ 2.0 dev. board. It uses the AT90USB1286 8 bit AVR 16 MHz microcontroller. I'm using the microcontroller to drive a small solid state relay. This was just a basic ...
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46 views

Getting bottom row of black boxes with LCD Display on atmega32 MCU?

I need some help with this, I am a completely new to programing MCU's but I am trying my best to get this working and I could relay use some help. I am using the Sparkfun Basic 16x2 Character LCD ...
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50 views

Is it possible for a Teensy 3.1 microcontroller to receive USB keyboard input?

As I've read, it is possible to have the teensy act as a keyboard for a computer. I would like to know if the opposite is possible - can I collect keystrokes through the USB port on the teensy. If ...
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2answers
87 views

AVR USART sending garbage

I'm trying to make an ATMega328P to send serial data to my computer and print onto Putty using an arduino board to do the USB to serial conversions. The data that's printed, however is garbage data. ...
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68 views

Why does USB signaling to microcontrollers need resistors

I'm currently trying to make a USB device with the ATMega16U2. On page 187 of the datasheet, there are unspecified resistors between the USB port and the pins of the microcontroller The Arduino Uno ...
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30 views

How to design a 3V3 device to be safely programmed by 5V ISP

I'm designing my first 3V3 circuit with ATmega8. While the uC itself supports both 5V and 3V3, some of components do not. I'm going to place ISP socket on board and I'm wondering how to ensure that a ...
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38 views

ATmega32u4 bootloader [migrated]

Hey all this would be my first encounter needing to burn the Arduino IDE bootloader onto a blank ATMega32u4 that I bought from Digikey. What all do I need to buy in order to program the bootloader ...
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38 views

AVR Assembler Labels

According to doc1022, p. 17 (AVR Assembler User Guide): User defined labels which are given the value of the location counter at the place they appear. My question is, what goes into the opcode ...
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27 views

Atmega 168A fuse programming

I'm currently programming over an Atmega 168A micro controller through a USB Tiny programmer and an ISP interface. The micro controller is set up with an external oscillator and an external person ...
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4answers
138 views

How often do AVR's actually glitch and need a watch-dog reset in the real-world?

Have you ever seen an otherwise happy AVR spontaneously glitch and require a reset? Assuming: a nice stead power supply that stays inside the specified range a correctly sized decoupling cap ...
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39 views

The difference between Atmel ATmega16u2-MU and -MUR

What is the difference between ATMEGA16U2-MU and ATMEGA16U2-MUR? Atmel lists these 2 codes in the table on their product page but I could not find any explanation in the datasheet.
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58 views

Input/output pin resistance for an AVR microcontroller

For example, when driving a logic-level MOSFET directly from a microcontroller, what is the smallest gate resistor that can be used? Specifically for AVR microcontrollers; i.e. this datasheet, the ...
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51 views

AVR IO Alternative Functions Priority

If in an AVR microcontroller there's at least two functions for example SPI, Analog Comp and GPIO pins in one 8bit PORT what's the priority of the functions? for example: If SPI enable first, and then ...
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62 views

AVR USART wait for AVR's reponse to continue text stream

AVR USART wait for AVR's reponse to continue protocol I am doing a senior project, and I need to send a large text file line by line to an AVR (atmega32) which will control a piano using ~36 ...
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56 views

Can you set the PWM output of an Atmel AVR to a specific frequency and have control over duty cycle?

I'm trying to drive an LED at 38kHz with a low duty cycle like 10% from an Atmel ATTiny88. The chip is currently running at 8MHz, but could be adjusted for this portion of code, if need be. Using ...
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42 views

Problem initializing 4-bit mode LCD(DEM 20486 SBH-PW-N)

I've got an ATMEGA16 with a LCD display DEM 20486 SBH-PW-N (datasheet) connected to port C like so C0 - RS C1 - RW C2 - E C3 - not Set C4 - D4 C5 - D5 C6 - D6 C7 - D7 D0-D3 are grounded I ...
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38 views

Anyone familiar with TI's ADS1210

I'm trying the build a two-channel thermometer using an ATMEGA328 and two ADS1210. I've connected both ADS1210 via the common SPI lines (SCLK, MOSI, MISO) to the ATMEGA328, for DRDY and CS I'm using ...
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59 views

AVR - NRF24L01+ : Encrypt Data Transmission

I have a pair of AVR's that communicate over the 2.4GHz link using NRF24l01+. The payload sent is 5 bytes long. Right now the payload sent is in clear format so that anyone with enough knowledge and ...
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3answers
61 views

Level Translator for AVR and microSD

I want to connect a microSD card in my AVR ATMEGA32, through SPI, which its operate with 5V. The microSD card i think that operates with 3.3V so, it is must to connected via bidirectinal level ...
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Programming ATMega2560 using USBasp

I own an USBasp programmer and have experience programming the ATMega16A microcontroller using the same.Also,I use WinAVR and a makefile to generate the .hex file. A new project demands the usage of ...
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34 views

Can't read/write to/from the atmega328p

I cant communicate with the Atmega328p. I've flashed fuses low: 0x59, high: 0xD9 and changed wiring. Now I've connected 16Mhz crystal to the XTAL1, XTAL2 pins, and 2x22pF to the crystal. But I can't ...
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96 views

ATMEGA328P SPI MMC/SDIO

I want to connect an ATMEGA328P to a mobile phone, a Samsung Galaxy S3 to interface some data. I need to use the microSD port behind the battery cover for this purpose, so here is the question, Is it ...
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47 views

How many clock cycles does reading digital input on an AVR microcontrollers take?

How many clock cycles does it take to read digital inputs in avr microcontrollers? For example, how many clock cycles would SomePreDeclaredByte = PINB; take?
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78 views

Wiznet Wiz820io (W5200) Module - No data on MISO Line

I had a working circuit with Wiznet W5100, but to get better performance I switched over to Wiznet W5200 (in Wiz820io module). This involved rewiring the pins, changing the register address and also ...
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63 views

How data transfers to micro-controllers memory?

I have been working with Arduino for a while now i thought of using AVR micro-controllers in the bread-board . I saw several tutorials on how to transfer .hex file to the AVR micro-controller . They ...
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2answers
36 views

Need help with pushbutton on atmega8

This is what I have: Atmega 8 wired for programming, confirmed working, programmer is my power supply. 2 leds connected via 470Ohm pull up reisistors to ports PORTB0, PORTB1 and to GROUND, working. ...