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Is each interrupt vector 2 bytes or 4 bytes in size on ATmega328P?
The data sheet says: Each interrupt vector occupies two instruction words in Atmel ATmega328P. Each word is 16 bites: Most AVR® instructions have a single 16-bit word format...
Thursday, 31 March 2022 - 20:18
Is there a difference between using the r1 register or the data address 0x1?
The ATmega328P datasheet says: each register is also assigned a data memory address, mapping them directly into the first 32 locations of the user data space. Which suggests...
Monday, 28 February 2022 - 19:44
Connecting Arduino directly to the serial port of an old PC (not USB)
Sorry about making yet another post about UART communication.   I'm trying to send a single character from my Arduino Uno to my PC using UART.   I'm not using a USB to...
Thursday, 20 January 2022 - 15:39
Tx port is constantly high even after enabling serial communication
I'm trying enable serial transmission (UART Tx) on my AVR atmega328p embedded on an Uno board. I'm trying to do all this without any of Arduino libraries except its...
Tuesday, 18 January 2022 - 14:54
How is a binary value of "0" transmitted in serial communication?
I'm going to use a simple LED circuit to demonstrate this (I know it's not a good example but I need to keep this simple). I'm also going to use USART, and more specifically the...
Saturday, 15 January 2022 - 18:40
What is the difference between a CPU register and the rest of volatile memory on AVR?
Going to use ATmega328P as an example.   It has all of its CPU and IO registers memory address mapped on an SRAM. A section of this SRAM is also used as volatile...
Thursday, 13 January 2022 - 00:04
What is the type of the __vector_x function?
As explained in this link:  https://www.avrfreaks.net/forum/...   `__vector_x` has a weak symbol which can be overwritten by a user for setting interrupt callbacks...
Monday, 3 January 2022 - 17:17
never mind
never mind
Wednesday, 29 December 2021 - 18:57
How does UART transfer data out of the TX pins?
My question is manly regarding this function in ArduinoCore-avr:   https://github.com/arduino/Ardui...   size_t HardwareSerial::write(uint8_t c)I can see that it...
Monday, 1 February 2021 - 15:45
Do we need a driver to talk to atmega328p from a PC
This question is more specific to Linux and how drivers are needed to talk to other peripherals. Another way to ask this question would be: Why do we need drivers to begin with?...
Friday, 10 July 2020 - 13:54
How does the "delay" mechanism work in atmega328p
In a regular Linux x86 environment, we can use the "sleep(size_t x)" C function to delay execution X number of seconds. Behind the scenes, libc calls "nanosecond" which...
Monday, 6 July 2020 - 21:22
What's the point of having USART in SPI Mode?
atmega328p supports USART in SPI Mode, which i'm guessing is different than UART in synchronous mode.   Why would this exist if one can either use UART, USART (for ...
Monday, 6 July 2020 - 19:18