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Questions tagged [avr]

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

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LCD Entry Mode Set and AVR MCU

I want to simulate **the Entry set mode ** function of and LCD based on HITACHI 44780 Controller. (Here is the datasheet.) The "Entry set mode" is given the following code of the 8 bits data ...
learn design's user avatar
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Analog switch for controlling LED

I need help/suggestions for the implementation of my schematic: In the schematic image pasted below, particularly look only at the charging IC, boost converter, analog switch, and ATTiny 1616 ...
Tahoor Asim's user avatar
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23 views

AVR128Dx TCB Input Capture issue

Ive made a code for reading SENT sensor using TCB interrupt with event system. It works 90% of the time, but those 10% seems like it doesnt read correct high pulse duration, mby someone will see, what ...
Ralfs Volis's user avatar
2 votes
1 answer
294 views

Memory view is showing multiple bytes change after a single byte is assigned to a register. Why?

I am debugging an issue I have on a legacy codebase that is running on an atxmega32c4u chip. I am writing single bytes to registers in PORTC, but the memory view is showing multiple bytes change. The ...
daviegravee's user avatar
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1 answer
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No touch points close to the edge of the screen

Just for fun and to learn, I'm writing code to drive a 800x480 TFT with resistive touch driven by an RA8875 and an ATmega328P and avr-libc. It works fine so far but when reading touch events, I don't ...
Torsten Römer's user avatar
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Which ATtiny TWI parameter provides more robust operation?

I'm using an ATtiny3226 as an I2C client (slave) interface in a robot, to get commands from the main controller (single master) using I2C on a shielded cable. There are brushless and servo motors ...
Tirdad Sadri Nejad's user avatar
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1 answer
41 views

AVR assembly indirect addressing: "Found no label/variable/constant named …"

I am currently trying to indirectly address the SRAM of the ATMega328P by using the following code: ...
user380637's user avatar
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48 views

SSD1306 display goes out-of-sync only if ATmega328 is reprogrammed

I have ATmega328 directly connected to the SSD1306 Display through I2C. Whenever I power up the ATmega, everything works great and the display works as expected. The problem occurs only when I upload ...
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Problems with OCR1B on Atmega328p

Trying to control 4 servos (SG90) using 4 pots on an arduino nano and the one connected to OC1B keeps having problems, with bits of jittering and it just not moving correctly (occasionally spinning), ...
jimothy's user avatar
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Why did fuse bits successfully reset using ICSP and USBASP programmer?

I read a lot about fuse bits in AVR microcontrollers and everyone says that fuse bits can be reset by using high-voltage programmer only, they can't be reset via UART<->ICSP. So, I've received ...
Alexander Perechnev's user avatar
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2 answers
68 views

Extended IO registers handling in AVR using Assembly language

I want to program the ADC module of arduino Mega2560 using Assembly language (for simulation and learning), I can initialise the ADC Module using Assembly and my program converts in the first ...
learn design's user avatar
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Manipulating EEPROM in AVR using assembly programming

In the following video(at 10min): https://www.youtube.com/watch?v=YELGX5XDCiY&list=PLgwJf8NK-2e55CdbY_WnY6pejPHoojCkJ&index=18 The microcontroller used in the video series is ATmega32. Let's ...
learn design's user avatar
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SPI: Write to display while reading multiple blocks from SD card

I'm reading BMP images with hundreds of kB's raw from an SD card and parse/write the image data to a TFT LCD with an AVR MCU with 2kB RAM. Reading a single block of 512 bytes with CMD17, passing it to ...
Torsten Römer's user avatar
2 votes
3 answers
208 views

Tightest finite wait loop possible in AVR8

I need a wait delay function with fine grained control of the delay. I came up with the fairly standard way ldi Rx, N lp: dec Rx brne lp This ...
Peter Rottengatter's user avatar
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2 answers
143 views

AVR ATmega328P if statement wrongly executed after reset

I have simplified the listing to bare minimum where I can still observe this behaviour. When this program is running, it works as expected. Button press causes LED to show up. The problem exist on ...
smajli's user avatar
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How to increase the Atmega32A input output pins

I’m using ATmega32A to control a system which have a 30 outputs and 30 inputs. The issue is that the ATmega32A have only 32 DIO pin which can be use as input output pins. So how can I increase the ...
abdalla zakaria's user avatar
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ATTiny85 won't reprogram

I am using a tiny AVR programmer to program code specifically this one, https://www.amazon.com/dp/B00B6KNJRY?psc=1&ref=ppx_yo2ov_dt_b_product_details , I can successfully upload code onto a blank ...
Ash Ketchup's user avatar
2 votes
1 answer
117 views

AVR32DA VIH threshold

I am looking into using an AVR32DA48 MCU for a design. The MCU will be powered at 5V and needs to interface with an IC at 3.3V. The IC is 5V tolerant and I am trying to figure out if a level ...
Mr.Y's user avatar
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How to identify all AVR MCUs (ATtiny and ATmega) that feature a factory-programmed unique ID

On Microchip's site, the "parametric search" table for microcontrollers does not have a filter column to select the models that feature a unique ID. Is there a way to list (enumerate) all ...
Cal-linux's user avatar
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Can WINC1500 be used with SPI for connecting to a router?

I'm planning to buy the WINC1500 WiFi module. I have heard that it contains a SPI layer, which can be used for telling the WINC1500 to connect to a router. But as I can see in the documentation, I ...
euraad's user avatar
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Ohmic load on AVR's SCK?

I have an ATTINY13, and almost all pins are used (only PB2 is free). What I need to add is a controllable ohmic load, which I believe best way to add is with an N-channel MOSFET, similarly with this ...
Daniel's user avatar
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2 answers
79 views

Can I treat the USB controller in the ATMEGA8U2 as seperate from the rest of the microcontroller?

I'm working on a project that runs on a battery, but can be connected to a computer for a serial connection/charging. In the documentation it lists an example of a bus powered USB controller with ...
Elliot Smith's user avatar
1 vote
3 answers
300 views

ATMEGA328 out of memory, but avr-size reports I still have a lot of space

I have a program written in C. I have 390 byte array defined and a long string value consisting of around 475 bytes. Now I hit a problem if I add more characters to the string value, around 30 bytes, ...
0x29a's user avatar
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4 votes
2 answers
1k views

Transmitting from PC via USART to MCU working but very slow

I am sending a small 16-Bit RGB BMP image file from my Linux PC via USART (with a loosely wired USB to serial converter) to an AVR ATmega MCU sitting on a breadboard, running at 8 MHz with the ...
Torsten Römer's user avatar
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0 answers
98 views

Graphical LCD With Atmega64

I have ATMEGA64 and LCM240128, The wiring is as below: And my code is ( I'm using codevision): ...
Mojtaba Miraki's user avatar
2 votes
1 answer
379 views

ATmega64 custom board is not programming

I have designed a custom board for ATmega64 as below: It's the first time I want to program it, and I get a "chip enable program error". I can program ATmega16 and ATmega8, but for ATmega64 ...
Mojtaba Miraki's user avatar
1 vote
1 answer
94 views

ATMega328p wakes immediately after sleep

I'm having issues with my current AVR-C project that runs on an ATMega328p. After issuing the sleep command the chip wakes up again immediately. I want to wakeup with an external interrupt, but while ...
Julian F. Weinert's user avatar
1 vote
2 answers
476 views

Assembly: AVR Studio alternatives for Linux [closed]

I had been using using AVR Studio on Windows to write assembly code for my MCUs (mainly for atmega8515) for a couple years. However, recently I transitioned to Linux and turns out there aren't any ...
Heather7283's user avatar
4 votes
1 answer
649 views

AVR code disassembly - what is this code doing?

I have read and disassembled the code from an Atmel8 microcontroller from a faulty oscilloscope. This is the start routine: ...
DrD's user avatar
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1 vote
2 answers
179 views

Dual Slope integrator voltmeter improvement in Design

So, I'm attempting to design a dual-slope integrator voltmeter. I have the following block diagram so far. Now an AVR microcontroller will have an ADC pin in the range of 0-5 Volts . So negative ...
Zipho Lunika's user avatar
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33 views

Regulating multiple +5V sources to one output to increase current, but avoid interference/noise

I'm designing a circuit with 4 USB 2.0 upstream ports that each connect to their own AVR (ATMEGA32U4), 1 master and 3 slave connected via I2C, master then communicates with a USB controller via SPI, ...
WiredOpposite's user avatar
2 votes
3 answers
706 views

AVR code - where is Z register pointing to?

I am disassembling AVR code from a bit of hardware. The processor is an Atmel-8. On restart, after setting the stack pointer, the program calls a subroutine that starts with: ...
DrD's user avatar
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2 votes
2 answers
409 views

3V oscillator to 5V µC with an 74HCT inverter (12.8 MHz) - bad idea?

I'd like to use an AVR (ATmega328P-AU to be precise) in combination with a fairly accurate oscillator for timing purposes. I stumbled upon the fact that oscillators which have greater accuracy mostly ...
Korbinian's user avatar
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0 answers
62 views

avr debugWIRE On chip debug system

I am new into avr and am working on atmega328p. I am not able to understand the avr debugwire system. What is this and how it works. I am seen the datasheet but am not getting a good clear ...
kam1212's user avatar
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1 answer
68 views

Multiplexed keyboard based on MOSFET for AVR gives sometimes wrong reading

I made simple example for multiplexed keyboard 2x2 on AVR. Like schematic below: And Source code: ...
Leszek Mazur's user avatar
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0 answers
63 views

AT90USB1286 bricks after disabling clock divider

I have an AT90USB1286 which is connected to a 16MHz external crystal oscillator. It is my understanding that by default from the factory the CKDIV fuse is enabled which makes the chip run at an ...
00728M's user avatar
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0 answers
52 views

Switching reference voltage with capacitor on AREF

I do two conversions (ratiometric measurement) with AREF = AVCC = VCC = 3 x AAA battery. AVCC is connected to VCC via an LC network as recommended in the data sheet of the ATmega328P. I would like ...
Torsten Römer's user avatar
0 votes
1 answer
134 views

Why is nothing happening on my CLKOUT pin, despite the RTC working fine? [closed]

I apologize for the (probably) trivial question -- I'm just starting to get back into coding for MCUs after a long hiatus, so please be patient with me. I'll preface this by acknowledging that there ...
uWaveMan's user avatar
0 votes
2 answers
90 views

ATMega32U4 USB design considerations

I'm desigining a board with ATMega32U4 microcontroller. The board will be minimal, and will feed the microcontroller from USB of an M.2 socket (E type) on a PC mainboard: Now, checking Leonardo's ...
Daniel's user avatar
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5 votes
3 answers
1k views

How can I do immediate addition in the Atmel AVR instruction set?

I've been doing some AVR assembly programming for a university course, and I recently happened upon a situation where I would have wanted an "add immediate" instruction. However, no such ...
Newbyte's user avatar
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0 votes
2 answers
465 views

Schematic design for CJMCU Beetle?

I have this bare ATMEGA32U4 breakout: There are no components on the backside, and I need to redesign this for my own purposes. I'm looking for the schematic design of this. Although I can reverse ...
Daniel's user avatar
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1 vote
1 answer
66 views

Cannot stop Microcontroller's Hardware Timer from running

I'm using an Atmel ATMega8 microcontroller to control a stepper motor. (Datasheet). Timer1 (a 16-bit hardware counter) is used in CTC mode to modulate an IO pin to provide the stepping signal to the ...
Wossname's user avatar
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2 answers
59 views

Driving 10ch outputs with 5V AVR

I use a 5V AVR (ATmega1284p) to measure some data. Depending on the data I would like to switch one of 10 outputs. Each of these outputs should have a LED (as an indicator and for debugging purposes) ...
Eimer Z.'s user avatar
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1 answer
52 views

How to make a circuit which can give divided voltage to ADC and can send a trigger pulse to INT0 when I press a button?

I connected 4 buttons to the ADC module of AVR-ATMega328p with different resistor values, To know which button is pressed this ...
in.yssh's user avatar
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3 votes
0 answers
52 views

PID H-bridge random current spikes

My H-bridge consists of 4 n-channel MOSFETs. The high side is driven by a basic bootstrap circuit, and the low side is directly driven from the MCU. Using a PID function to control the motor by its ...
Ralfs Volis's user avatar
1 vote
1 answer
387 views

How do I measure distance of Ultrasonic Sensor HC-SR04 using the ATmega328P Timer Input Capture?

I am using an ATmega328P MCU with an 16 MHz external oscillator. I need to measure distance of Ultrasonic Sensor HC-SR04 using the ATmega328P Timer 1 Input Capture interrupt. I have to measure the ...
Pumbaa's user avatar
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0 votes
1 answer
83 views

Software serial not sending the first byte correctly

I implemented the following program to send data to a serial monitor.When I run it, I expect to see abcd but I always see ⸮bcd: <...
kovac's user avatar
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4 votes
3 answers
428 views

Are ATmega48/168/328 suitable for automotive applications?

I'm trying to figure out if it's ok to use ATmega48 in a homemade project involving some safety-related aspects with moving vehicles. (the project will be a control board for excavator joysticks) ...
floppydisk's user avatar
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1 answer
142 views

ESP8266 responds with gibberish and 'ready' to AT commands from C program

I have gotten the ESP8266 working by sending commands manually from the TTY. Now, I'm trying to connect to wifi using the following C program: ...
kovac's user avatar
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6 votes
1 answer
460 views

How does USART know which port to use for IO?

I'm trying to learn to use USART on an ATmega328P. I'm using this datasheet. I'm using the following code to echo characters I type on my terminal: ...
kovac's user avatar
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