i2cmaster.c

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/*
 * Copyright (c) 2010, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the Contiki operating system.
 *
 */

/**
 * \file
 *         I2C communication device drivers for Zolertia Z1 sensor node.
 * \author
 *         Enric M. Calvo, Zolertia <ecalvo@zolertia.com>
 *         Marcus Lundén, SICS <mlunden@sics.se>
 */

#include "i2cmaster.h"
#include "isr_compat.h"

signed char tx_byte_ctr, rx_byte_ctr;
unsigned char rx_buf[2];
unsigned char *tx_buf_ptr;
unsigned char *rx_buf_ptr;
unsigned char receive_data;
unsigned char transmit_data1;
unsigned char transmit_data2;
unsigned char prescale_lsb = I2C_PRESC_Z1_LSB;
unsigned char prescale_msb = I2C_PRESC_Z1_MSB;
volatile unsigned int i;  /* volatile to prevent optimization */

/* ------------------------------------------------------------------------------
 * Change the data rate prior initializing transmission or reception
 * ----------------------------------------------------------------------------- */
void
i2c_setrate(uint8_t p_lsb, uint8_t p_msb)
{
  prescale_lsb = p_lsb;
  prescale_lsb = p_msb;
}
/* ------------------------------------------------------------------------------
 * This function initializes the USCI module for master-receive operation.
 * ----------------------------------------------------------------------------- */
void
i2c_receiveinit(uint8_t slave_address)
{
  UCB1CTL1 = UCSWRST;                    /* Enable SW reset */
  UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC;  /* I2C Master, synchronous mode */
  UCB1CTL1 = UCSSEL_2 | UCSWRST;         /* Use SMCLK, keep SW reset */
  UCB1BR0 = prescale_lsb;                /* prescaler (default 400 kHz) */
  UCB1BR1 = prescale_msb;
  UCB1I2CSA = slave_address;           /* set slave address */
  UCB1CTL1 &= ~UCTR;                 /* I2C Receiver */
  UCB1CTL1 &= ~UCSWRST;                  /* Clear SW reset, resume operation */
  UCB1I2CIE = UCNACKIE;
#if I2C_RX_WITH_INTERRUPT
  UC1IE = UCB1RXIE;                      /* Enable RX interrupt if desired */
#endif
}
/* ------------------------------------------------------------------------------
 * Initializes USCI for master-transmit operation.
 * ------------------------------------------------------------------------------ */
void
i2c_transmitinit(uint8_t slave_address)
{
  UCB1CTL1 |= UCSWRST;               /* Enable SW reset */
  UCB1CTL0 |= (UCMST | UCMODE_3 | UCSYNC); /* I2C Master, synchronous mode */
  UCB1CTL1 = UCSSEL_2 + UCSWRST;           /* Use SMCLK, keep SW reset */
  UCB1BR0 = prescale_lsb;                  /* prescaler (default 400 kHz) */
  UCB1BR1 = prescale_msb;
  UCB1I2CSA = slave_address;             /* Set slave address */
  UCB1CTL1 &= ~UCSWRST;                    /* Clear SW reset, resume operation */
  UCB1I2CIE = UCNACKIE;
  UC1IE = UCB1TXIE;              /* Enable TX ready interrupt */
}
/* ------------------------------------------------------------------------------
 * This function is used to start an I2C communication in master-receiver mode WITHOUT INTERRUPTS
 * for more than 1 byte
 * ------------------------------------------------------------------------------ */
static volatile uint8_t rx_byte_tot = 0;
uint8_t
i2c_receive_n(uint8_t byte_ctr, uint8_t *rx_buf)
{

  rx_byte_tot = byte_ctr;
  rx_byte_ctr = byte_ctr;
  rx_buf_ptr = rx_buf;

  while((UCB1CTL1 & UCTXSTT) || (UCB1STAT & UCNACKIFG))   /* Slave acks address or not? */
    PRINTFDEBUG("____ UCTXSTT not clear OR NACK received\n");

#if I2C_RX_WITH_INTERRUPT
  PRINTFDEBUG(" RX Interrupts: YES \n");

  /* SPECIAL-CASE: Stop condition must be sent while receiving the 1st byte for 1-byte only read operations */
  if(rx_byte_tot == 1) {                /* See page 537 of slau144e.pdf */
    dint();
    UCB1CTL1 |= UCTXSTT;    /* I2C start condition */
    while(UCB1CTL1 & UCTXSTT)           /* Waiting for Start bit to clear */
      PRINTFDEBUG("____ STT clear wait\n");
    UCB1CTL1 |= UCTXSTP;    /* I2C stop condition */
    eint();
  } else {                              /* all other cases */
    UCB1CTL1 |= UCTXSTT;    /* I2C start condition */
  }
  return 0;

#else
  uint8_t n_received = 0;

  PRINTFDEBUG(" RX Interrupts: NO \n");

  UCB1CTL1 |= UCTXSTT;    /* I2C start condition */

  while(rx_byte_ctr > 0) {
    if(UC1IFG & UCB1RXIFG) {    /* Waiting for Data */
      rx_buf[rx_byte_tot - rx_byte_ctr] = UCB1RXBUF;
      rx_byte_ctr--;
      UC1IFG &= ~UCB1RXIFG;     /* Clear USCI_B1 RX int flag */
      n_received++;
    }
  }
  UCB1CTL1 |= UCTXSTP;    /* I2C stop condition */
  return n_received;
#endif
}
/* ------------------------------------------------------------------------------
 * This function is used to check if there is communication in progress.
 * ------------------------------------------------------------------------------ */
uint8_t
i2c_busy(void)
{
  return UCB1STAT & UCBBUSY;
}
/*----------------------------------------------------------------------------
 * Setup ports and pins for I2C use.
 * ------------------------------------------------------------------------------ */

void
i2c_enable(void)
{
  I2C_PxSEL |= (I2C_SDA | I2C_SCL);    /* Secondary function (USCI) selected */
  I2C_PxSEL2 |= (I2C_SDA | I2C_SCL);   /* Secondary function (USCI) selected */
  I2C_PxDIR |= I2C_SCL;                /* SCL is output (not needed?) */
  I2C_PxDIR &= ~I2C_SDA;         /* SDA is input (not needed?) */
  I2C_PxREN |= (I2C_SDA | I2C_SCL);    /* Activate internal pull-up/-down resistors */
  I2C_PxOUT |= (I2C_SDA | I2C_SCL);    /* Select pull-up resistors */
}
void
i2c_disable(void)
{
  I2C_PxSEL &= ~(I2C_SDA | I2C_SCL);    /* GPIO function selected */
  I2C_PxSEL2 &= ~(I2C_SDA | I2C_SCL);   /* GPIO function selected */
  I2C_PxREN &= ~(I2C_SDA | I2C_SCL);    /* Deactivate internal pull-up/-down resistors */
  I2C_PxOUT &= ~(I2C_SDA | I2C_SCL);    /* Select pull-up resistors */
}
/* ------------------------------------------------------------------------------
 * This function is used to start an I2C communication in master-transmit mode.
 * ------------------------------------------------------------------------------ */
static volatile uint8_t tx_byte_tot = 0;
void
i2c_transmit_n(uint8_t byte_ctr, uint8_t *tx_buf)
{
  tx_byte_tot = byte_ctr;
  tx_byte_ctr = byte_ctr;
  tx_buf_ptr = tx_buf;
  UCB1CTL1 |= UCTR + UCTXSTT;    /* I2C TX, start condition */
}
/*----------------------------------------------------------------------------*/
ISR(USCIAB1TX, i2c_tx_interrupt)
{
  /* TX Part */
  if(UC1IFG & UCB1TXIFG) {         /* TX int. condition */
    if(tx_byte_ctr == 0) {
      UCB1CTL1 |= UCTXSTP;     /* I2C stop condition */
      UC1IFG &= ~UCB1TXIFG;    /* Clear USCI_B1 TX int flag */
    } else {
      UCB1TXBUF = tx_buf_ptr[tx_byte_tot - tx_byte_ctr];
      tx_byte_ctr--;
    }
  }
  /* RX Part */
#if I2C_RX_WITH_INTERRUPT
  else if(UC1IFG & UCB1RXIFG) {    /* RX int. condition */
    rx_buf_ptr[rx_byte_tot - rx_byte_ctr] = UCB1RXBUF;
    rx_byte_ctr--;
    if(rx_byte_ctr == 1) { /* stop condition should be set before receiving last byte */
      /* Only for 1-byte transmissions, STOP is handled in receive_n_int */
      if(rx_byte_tot != 1) {
        UCB1CTL1 |= UCTXSTP;       /* I2C stop condition */
      }
      UC1IFG &= ~UCB1RXIFG;          /* Clear USCI_B1 RX int flag. XXX Just in case, check if necessary */
    }
  }
#endif
}

ISR(USCIAB1RX, i2c_rx_interrupt)
{
  if(UCB1STAT & UCNACKIFG) {
    PRINTFDEBUG("!!! NACK received in RX\n");
    UCB1CTL1 |= UCTXSTP;
    UCB1STAT &= ~UCNACKIFG;
  }
}