// function to initialize UART
void uart_init(uint32_t Desired_Baudrate) {
// If its not already set, calculate the baud rate dynamically,
// based on current microcontroller speed and user specified
// desired baudrate.
#ifndef UBBR
#define UBBR ((F_CPU)/(Desired_Baudrate*8UL)-1)
#endif
// Set to double speed mode.
SS_UCSRnA |= (1 << SS_U2Xn);
// Set baud rate.
SS_UBRRnH = (uint8_t)(UBBR >> 8);
SS_UBRRnL = (uint8_t)UBBR;
// Enable receiver, transmitter, and RxComplete interrupt
SS_UCSRnB = (1 << SS_RXENn) | (1 << SS_TXENn) | (1 << SS_RXCIEn);
// Set frame format: 8data, 1 stop bit
SS_UCSRnC = (1 << SS_USBSn) | (1 << SS_UCSZn0) | (1 << SS_UCSZn1);
// Enable the Global Interrupt Enbl flag to process interrupts
DIGITAL_SET_OUT(SS_UART_TXE); // Set nRX enable and TX enable as outputs
DIGITAL_SET_OUT(SS_UART_nRXE);
DIGITAL_SET_LOW(SS_UART_TXE); // Set nRX enable and TX enable to 0
DIGITAL_SET_LOW(SS_UART_nRXE); // Enable RX and disable TX
DIGITAL_PULLUP_ON(SS_UART_RX);
sei(); // Enable interrupts
}
// Public functions called from main.c
void initDigital() {
DIGITAL_PULLUP_ON(IN0);
DIGITAL_SET_HIGH(IN1);
DIGITAL_SET_LOW(IN2);
DIGITAL_SET_LOW(IN3);
// TODO(tobinsarah): allow configuration as input/output for each relevant pin
DIGITAL_SET_IN(IN0);
DIGITAL_SET_OUT(IN1);
DIGITAL_SET_OUT(IN2);
DIGITAL_SET_OUT(IN3);
}
void USART_Transmit_Stop() {
DIGITAL_SET_LOW(SS_UART_TXE); // Set TX enable to 1
}