adc.zip_Atmega8 ADC_reading

// Based on ap note AVR306 by ATMEL // Routines for interrupt controlled USART // Last modified: 26 October 2006 // Changed to work with WinAVR 20060421 // Changed : 3 Nov 2005 // changed rx buffer access, added checks for non-atomic interrupt pointer modification // changed function name DataInReceiveBuffer to USART_DataRx // modified: 10 APR 2005 // added double speed baud support; // Modified by: Murray Horn // this file includes the tx and rx routines for a single uart mega avr. // seperate tx and rx ques are available and can be sized in the .inc file // a string tx feature from rom has been added (uart_puts_p). // Includes #include <inttypes.h> #include <avr/interrupt.h> #include <avr/pgmspace.h> // used for the string printing feature #include <uart001.h> // Prototypes #define circular_t uint8_t // Static Variables static uint8_t USART_RxBuf[USART_RX_BUFS]; static volatile circular_t USART_RxHead; static volatile circular_t USART_RxTail; static uint8_t USART_TxBuf[USART_TX_BUFS]; static volatile circular_t USART_TxHead; static volatile circular_t USART_TxTail; //----------------------------------------------------- // Initialize USART void USART_Init( uint16_t baudrate,uint8_t setup) { //------------------------------ // the doublespeed selector if (baudrate > 0x7ff) { baudrate += 1; baudrate = baudrate >> 1; baudrate -= 1; UCSRA = 0; } else UCSRA = (1<<U2X); //------------------------------ // Set the baud rate UBRRH = (uint8_t)(0x0f &(baudrate >> 8)); UBRRL = (uint8_t) baudrate; // Enable UART receiver and transmmitter and receive int UCSRB = (1<<RXEN)|(1<<TXEN)|(1<<RXCIE); // Set frame format: data bits, stop bits,parity etc UCSRC = (1<<URSEL)| setup ; // set the uart bits,baudrate,stop bits // Flush buffers USART_RxTail = 0; USART_RxHead = 0; USART_TxTail = 0; USART_TxHead = 0; } //----------------------------------------------------- //----------------------------------------------------- // RX Interrupt handler // the only function that is allowed to change rx_head SIGNAL(SIG_UART_RECV) { uint8_t data; circular_t tmp_head,nxt_head,tmp_tail; // Read the received data data = UDR; // Calculate buffer index tmp_head = USART_RxHead; nxt_head = ( tmp_head + 1 ) & USART_RX_BUFFER_MASK; // non atomic protection do tmp_tail = USART_RxTail; while (tmp_tail != USART_RxTail); if ( nxt_head == tmp_tail) { // ERROR! Receive buffer overflow } else { USART_RxBuf[tmp_head] = data; // Store received data in buffer USART_RxHead = nxt_head; // Store new index } } //----------------------------------------------------- //----------------------------------------------------- // TX Interrupt handler // the only function that is allowed to change tx_tail SIGNAL(SIG_UART_DATA) { circular_t tmp_tail,tmp_head; // non atomic protection do tmp_head = USART_TxHead; while (tmp_head != USART_TxHead); tmp_tail = USART_TxTail; // Check if all data is transmitted if ( tmp_head != tmp_tail ) { // Calculate buffer index UDR = USART_TxBuf[tmp_tail]; // Start transmition tmp_tail = ( tmp_tail + 1 ) & USART_TX_BUFFER_MASK; USART_TxTail = tmp_tail; // Store new index } else { UCSRB &= ~(1<<UDRIE); // Disable UDRE interrupt } } //----------------------------------------------------- //----------------------------------------------------- // RX function // the only function that is allowed to change rx_tail uint8_t USART_Receive( void ) { circular_t tmp_tail,tmp_head; uint8_t b; do { tmp_tail = USART_RxTail; // // double get the head to ensure no interrupt based corruption of the pointer do tmp_head = USART_RxHead; while (tmp_head != USART_RxHead); // non atomic protection } while (tmp_head == tmp_tail); // Wait for incomming data b = USART_RxBuf[tmp_tail]; tmp_tail = ( tmp_tail + 1 ) & USART_RX_BUFFER_MASK; // Calculate buffer index USART_RxTail = tmp_tail; // Store new index return b; // Return data } //----------------------------------------------------- //----------------------------------------------------- // TX function // the only function that is allowed to change USART_TxHead void USART_Transmit( uint8_t data ) { circular_t tmp_head,nxt_head,tmp_tail; // Calculate buffer index tmp_head = USART_TxHead; nxt_head = ( tmp_head + 1 ) & USART_TX_BUFFER_MASK; // Next point in buffer // wait for free space do { // non atomic protection do tmp_tail = USART_TxTail; while (tmp_tail != USART_TxTail); } while (nxt_head == tmp_tail); USART_TxBuf[tmp_head] = data; // Store data in buffer USART_TxHead = nxt_head; // Store new index UCSRB |= (1<<UDRIE); // Enable UDRE interrupt } //----------------------------------------------------- //----------------------------------------------------- uint8_t USART_DataRx( void ) { uint8_t again; circular_t tmp_tail,tmp_head; // protection against interrupt interference (non atomic access) do { again = 0; tmp_head = USART_RxHead; tmp_tail = USART_RxTail; if (tmp_head != USART_RxHead) again = 1; if (tmp_tail != USART_RxTail) again = 1; } while (again); if ( tmp_head == tmp_tail ) return(0); else return(1); } //----------------------------------------------------- //----------------------------------------------------- // write a string to the usart from the program memory void uart_puts_p(const char *progmem_s ) { register char c; while ( (c = pgm_read_byte(progmem_s++)) ) USART_Transmit(c); } //-----------------------------------------------------