Suppose we need to transfer data in one direction only, for instance. So if we need to use a single line and be able to transmit and receive data – use Half Duplex mode and TX complete interrupts. This feature is usually used in half-duplex transmission mode when transmitter and receiver share same line like in RS-485 standard. After this interrupt there is no physical transmission on pins.

We have empty transmit buffer UDR0 and Transmit Shift Register in this case. It will occur when Transmit Shift Register has been shifted out and is empty. Probably a natural question comes out: Why there are two interrupts for transmission? The explanation is simple. If you look into the datasheet, you will find that USART0 in Atmega328 has three interrupt sources: So there is a better way of using USART – so-called Interrupt Driven USART. In reception mode, we can’t predict when actual data will be received, so the program has to check for received data indicating flag constantly and don’t miss it as next upcoming byte may clear it. First of all, using loops to poll for transmitting buffer to be ready or wait for received byte consumes lots of processing power, what also leads to more power consumption. These are OK to use, but in more intense and power-critical applications, they are not practical and efficient. Figure that out first.In the last part of the USART tutorial, we discussed the most straightforward way of implementing USART transmitting and receiving routines. You don't seem to even know what you're doing, you don't seem to know which parts work and which parts don't. Note how I never even mentioned part numbers here? That's because it's irrelevant for this strategy. Still nothing? Make sure that LED is even in working order.Start reducing numbers until you find the pin your LED is really connected to. Now you should definitely see your LED blink. No blink? Change Blink to blink EVERY output pin your processor has.Still nothing? Upload Blink with the pin you think it is.

If you get the response: see that your solder links are OK and the LED the correct way around and connected to the correct pin.If nothing, your Serial communication fails somewhere. See what comes back on the Serial monitor (you're printing things).Then, what did you do to debug? The obvious steps would be verify Serial comms, verify soldering joints, verify pin number: According to the code when we send '1' from PC, the board should glow the LED.Īnd when we send '0' the LED should be off.įirst of all: do go and read the sticky so at least you know the info we need and how to properly post code.

Atmega8 uart program