Serial I/O
Serial I/O
Embedded Files
Implemented in C, this program is designed to repeatedly transmits the characters of a string through the built-in USART port on the AVR Xplained mini 328 board. It begins by defining the CPU clock frequency and the Baud rate by calculating the necessary register for accurate timing. Using the USART hardware of the AVR, the registers are initialized, enabling the receiver and transmitter to set up the 8-bit data format. The other function ‘Transmit()’ handles the transmission of each character in the string correctly. It sends each character of the string sequentially, waiting for the transmit buffer to empty before sending the next character. The program runs in an infinite loop since there is no final break statement{until power is lost). In the main loop, the program iterates through every character in the string, sending over each letter to the transmit function. There is a 500ms delay between each transmission.
Implemented in C, this program is designed to repeatedly transmits the characters of a string through the built-in USART port on the AVR Xplained mini 328 board. It begins by defining the CPU clock frequency and the Baud rate by calculating the necessary register for accurate timing. Using the USART hardware of the AVR, the registers are initialized, enabling the receiver and transmitter to set up the 8-bit data format. The other function ‘Transmit()’ handles the transmission of each character in the string correctly. It sends each character of the string sequentially, waiting for the transmit buffer to empty before sending the next character. The program runs in an infinite loop since there is no final break statement{until power is lost). In the main loop, the program iterates through every character in the string, sending over each letter to the transmit function. There is a 500ms delay between each transmission.
The Registers and Variables Utilized:
The Registers and Variables Utilized:
The program uses six USART registers: UCSR0A, UCSR0B, UCSR0C, UBRR0H, UBRR0L. UCSR0A is used to check for the transmit buffer's status: busy or empty. UCSR0B is used to enable or disable the receiver and transmitter; in this case, it was enabled. UCSR0C is used to configure the 8 bit data format. UBRR0H and UBRR0L are used to set the baud rate for the high and low bits of UBRR0 - the USART baud rate register. In addition to registers, variables are also utilized in the code. The variable ‘userString[]’ is an array that is used to store the string that will be transmitted. The variable following it,’strSize’ stores the number of characters in the array ‘userString[]’. Other variables such as F_CPU, BAUD, and BAUDRATE are also used in the program. While F_CPU defines the CPU clock frequency, BAUD specifies the baud rate for the USART communications. Lastly, BAUDRATE stores the calculated value that is stored in UBRR0.
External Connections:
External Connections:
The FT232R Breakout board and the Atmel Xplained Mini board were utilized for this assignment. Pin PD1 on the Atmel board was connected to the TXD pin on the FT232R board using a wire to set up the transmission. The grounds of both boards were also connected.
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