Post by thread:sending data via serial port to 16C84

>> I'm wondering if you have any code to send data via serial port to PIC >> 16C84 >> >> Thank you very much Gus, Try this. It isn't fully tested, but should work. Andy #ifndef CLRWDT #include "pic.h" #endif #include "defs.h" #include "prog.h" #include "progpins.h" #include "rs485.h" #if defined(_16C558) byte bank1 txbuffer[MAX_RS485_TX_BUFFER]; // Transmit character buffer byte rxbuffer[MAX_RS485_RX_BUFFER]; // Received character buffer #endif byte bank1 txcount, txhead, txtail, rxcount, rxhead, rxtail; byte TXREG; // Character bei ng transmitted (shift register) enum TXSTATE { TX_IDLE, TX_START, TX_DATA, TX_STOP = TX_DATA+8 // Stays in here for a while... }; byte RCREG; // Character bei ng received (shift register) enum RXSTATE { RX_WAIT_FOR_START, RX_IN_START, RX_IN_DATA, RX_IN_STOP }; byte TXState, // Transmitter S tate Machine RXState; // Receiver Stat e Machine #define UART_TIMER0_FULLBIT ((byte)(254-104)) // 104 u S delay #define UART_TIMER0_HALFBIT ((byte)(254-52)) // 52 u S delay // ////////////////////////////////////////////////////////////////////////////// // // Interrupt Handler - UART // ////////////////////////////////////////////////////////////////////////////// // // Author: Andy Kunz // Date: n/a // Modifications: none // static void interrupt UART (void) { /* The ISR is called regularly once per bit at 9600 bps = every 104uS when transmitting. Receiving is handled in true bit-bop fashion, since it can't do much until the data is receiv ed and analyzed anyway. The receiver hardware is configured so as to permit INT interrupts to ma rk the start of a bit. This code does not permit simultaneous transmit and receive. That's fin e, because the hardware won't permit it either. */ if (INTF) // Receiver gene rated an interrupt? { TMR0 = UART_TIMER0_HALFBIT; // Set up a 1/2- bit time delay RXState = RX_IN_START; // Flag that we' re checking the start bit INTE = 0; // Disable furth er edge interrupts until byte is complete INTF = 0; T0IF = 0; // Clear possibl e TMR0 overflow false } if (T0IF) // 8-bit TMR0 ov erflowed { T0IF = 0; // Clear interru pt TMR0 = UART_TIMER0_FULLBIT; // Reload the bi t-timer // RECEIVE if (RXState) // Is the r eceiver active? { if (RXState == RX_IN_START) // Yes, is it the start bit (must still be logic 0 here) { if (SER_RX) { RXState = RX_WAIT_FOR_START; INTF = 0; // It was a "1", so we must re-enable the INT peripheral INTE = 1; } } else if (RXState == RX_IN_STOP) // Are we g etting the stop bit? { RXState = RX_WAIT_FOR_START; // Yes, mar k end of receipt INTF = 0; // Re-enabl e start bit detection hardware INTE = 1; if (rxcount < MAX_RS485_RX_BUFFER)// Stick re ceived character in circular buffer { rxbuffer[rxtail] = RCREG; rxtail++; rxcount++; if (rxtail >= MAX_RS485_RX_BUFFER) rxtail = 0; } } else { RCREG = RCREG >> 1; // Shift th e received byte down 1 bit if (!(SER_RX)) // Insert i nverted data bit RCREG |= 0x80; } } // TRANSMIT else // Must be trans mitter-side (or nothing) { if (TXState == TX_IDLE) // transmit ter is idle? { if (txcount != 0) // if char acters to send { SER_DIR = SER_TRANSMIT; // Set direction properly SER_TX = 0; // Start with a start bit TXREG = txbuffer[txhead];// Prepare character to send txhead++; // Bump pointer & counter if (txhead >= MAX_RS485_TX_BUFFER) txhead = 0; txcount--; TXState++; // Record new state } else SER_DIR = SER_RECEIVE; // Allow da ta to flow back into here } else // transmitter i s pumping out data { SER_TX = ! (TXREG & 0x01); // Output i nverted data bit TXREG = (TXREG >> 1) | 0x80; // Shift do wn for next bit & insert a stop bit TXState++; // Bump sta te counter if (TXState == TX_STOP+1) // End of t he byte? TXState = TX_IDLE; // Reset to 0 } } } } //*********************************************************************** // // RS485_PUTC - Writes char to RS-485 buffer // //*********************************************************************** void rs485_putc (char c) // Write single character into t ransmit buffer { do CLRWDT(); while (txcount == MAX_RS485_TX_BUFFER); // Wait until there's room in th e buffer if (txtail >= MAX_RS485_TX_BUFFER) // Limit txtail txtail = 0; txbuffer[txtail] = c; // Grab incoming character txtail++; // Bump tail txcount++; // and counter } //*********************************************************************** // // RS485_GETC - Reads char from RS-485 buffer // //*********************************************************************** char rs485_getc (void) // Get next character from recei ve buffer { char c; while (rxcount == 0) // Wait for something to come in CLRWDT(); rxcount--; // Decrement counter c = rxbuffer[rxhead]; // fetch character rxhead++; // Bump pointer if (rxhead >= MAX_RS485_RX_BUFFER) // and wrap it around rxhead = 0; return (c); } //*********************************************************************** // // RS485_KBHIT - Return number of chars in buffer // //*********************************************************************** byte rs485_kbhit (void) // Get next character from recei ve buffer { return (rxcount); } //*********************************************************************** // // RS485_INIT - sets up everything, starts it going // //*********************************************************************** void rs485_init (void) { di (); // Disable interrupts before mon keying around here txcount = 0; // First initialize variables txhead = 0; txtail = 0; rxcount = 0; rxhead = 0; rxtail = 0; TRIS_SER_RX = 1; // Always the correct direction here TRIS_SER_TX = 1; // Set up chip so that initially it is a receive-only device TRIS_SER_DIR = 1; // This gets changed around once we seize control of the bus SER_DIR = SER_RECEIVE; // Allow data to flow into this PIC RXState = RX_WAIT_FOR_START; // Just looking TXState = TX_IDLE; // Nothing happening TMR0 = UART_TIMER0_FULLBIT; // Set up for start of edge T0IE = 1; // Enable timer0 interrupt } //*********************************************************************** // // RS485_GRAB - grabs control of serial bus // //*********************************************************************** void rs485_grab (void) { di (); SER_DIR = SER_RECEIVE; // Allow data to flow into this PIC TRIS_SER_DIR = 0; // Seize control of direction li ne, force to receive mode TRIS_SER_TX = 0; // Seize control of transmit dat a line, force to idle state (stop bit) TRIS_SER_RX = 1; // Always the correct direction here ei (); } The important pins in PROGPINS.H are: #define PIN(n,x,y) static volatile bit n @ (unsigned)&x*8+y PIN (SER_RX, PORTB,0); // IN 6 7 RS-485 RX pin PIN (SER_TX, PORTB,1); // I/O 7 8 RS-485 TX pin (set to in put when PIC17 is active) PIN (SER_DIR, PORTB,2); // I/O 8 9 Serial Direction control for RS-485 (set to input when PIC17 is active) ================================================================== Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA ==================================================================