uart.c

hop file for Nordic nrf24e1

/*= uart.c =========================================================================================
 *
 * Copyright (C) 2004 Nordic VLSI ASA
 *
 * Author(s): Ole Saether
 *
 * COMPILER:
 *
 *   This program has been tested with Keil C51 V7.08
 *
 * $Revision: 1 $
 *
 *==================================================================================================
*/
#include <Nordic\reg24e1.h>
#include "uart.h"

static volatile unsigned char idata rxbuf[32];  // Uart recieve buffer
static volatile unsigned char rxrp;             // Uart receive buffer read pointer
static volatile unsigned char rxwp;             // Uart receive buffer write pointer
static volatile unsigned char rxn;              // Number of characters left in receive buffer
static volatile unsigned char idata txbuf[32];  // Uart transmit buffer
static volatile unsigned char txrp;             // Uart transmit buffer read pointer
static volatile unsigned char txwp;             // Uart transmit buffer write pointer
static volatile unsigned char txn;              // Number of characters left to send

void UartInit(void)
{
    rxn = rxwp = rxrp = 0;
    txn = txwp = txrp = 0;

    RCAP2H = 0xFF;
    RCAP2L = 0xF7;                              // 57600@16MHz
    SCON = 0x50;                                // Serial port mode1, enable receiver
    T2CON = 0x34;                               // Rx and Tx clock from Timer2, enable Timer2
    P0_DIR |= 0x02;                             // P0.1 (RxD) is an input
    P0_ALT |= 0x06;                             // Select alternate functions on pins P0.1 and P0.2
    ES = 1;                                     // Enable serial interrupt
}

void Serial (void) interrupt 4 using 2
{
    if (RI)
    {
        RI = 0;                                 // Clear receive interrupt bit
        rxbuf[rxwp] = SBUF;                     // Store received character in receive buffer
        rxwp = (rxwp + 1) & 0x1f;               // Advance write pointer
        rxn++;                                  // Increment number of characters in buffer
    }
    if (TI)
    {
        TI = 0;                                 // Clear transmit interrupt bit
        txn--;                                  // Decrement number of characters to send
        if (txn > 0)                            // More characters in transmit buffer?
        {
            SBUF = txbuf[txrp];                 // Yes, store next character in uart buffer
            txrp = (txrp + 1) & 0x1f;           // Advance read pointer
        }
    }
}

void PutChar(char c)
{
    while(txn > 31)                             // Wait while transmit buffer is full
        ;
    if (txn == 0)                               // If all previous characters are sent...
    {
        SBUF = c;                               // ...write character directly to the uart...
        txn = 1;
    } else
    {
        txbuf[txwp] = c;                        // ...else write it to the transmit buffer
        txwp = (txwp + 1) & 0x1f;               // Advance write pointer
        ES = 0;                                 // Disable serial interrupt while...
        txn++;                                  // ...incrementinfg numnber of characters to send
        ES = 1;                                 // Enable serial interrupt
    }
}

unsigned char GetChar(void)
{
    unsigned char c;

    while(rxn == 0)                             // Wait until there is at least one character in the buffer
        ;
    c = rxbuf[rxrp];                            // Read next character from buffer
    rxrp = (rxrp + 1) & 0x1f;                   // Advance buffer read pointer
    ES = 0;                                     // Disable serial interrupt while...
    rxn--;                                      // ...decrementing number of characters in buffer
    ES = 1;                                     // Enable serial interrupt
    return c;
}