hpli2cm.nc

传感器网络中的嵌入式操作系统源代码

// $Id: HPLI2CM.nc,v 1.1.10.5 2003/08/26 09:08:16 cssharp Exp $

/*									tab:4
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 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS."
 *
 * Copyright (c) 2002-2003 Intel Corporation
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE     
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 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300, Berkeley, CA, 
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 */
/*
 *
 * Authors:		Phil Buonadonna
 * Date last modified:  $Id: HPLI2CM.nc,v 1.1.10.5 2003/08/26 09:08:16 cssharp Exp $
 *
 * HPLI2CM: Hardware based I2C for the ATmega128 series microcontroller.
 * Note: Hardware HPLI2C USES DIFFERENT PINS than the software based
 * I2CM used on earlier microcontrollers. Edit I2CC.nc to achieve the desired
 * configuration connection to hardware or software support.
 *
 */

/**
 * @author Phil Buonadonna
 */


module HPLI2CM
{
  provides {
    interface StdControl;
    interface I2C;
  }

}
implementation
{
  // global variables
  char state;           	// maintain the state of the current process
  char local_data;		// data to be read/written
  result_t result;

  // define constants for state
  enum {USR = 1,  // Unaddressed slave receiver or idle 
	MT,	  // Master Transmitter
	MR,	  // Master Receiver
	ST,	  // Slave Transmitter
	SR};	  // Slave Receiver

  // define TWI device status codes. 
  enum {
    TWS_BUSERROR	= 0x00,
    TWS_START		= 0x08,
    TWS_RSTART		= 0x10,
    TWS_MT_SLA_ACK	= 0x18,
    TWS_MT_SLA_NACK	= 0x20,
    TWS_MT_DATA_ACK	= 0x28,
    TWS_MT_DATA_NACK	= 0x30,
    TWS_M_ARB_LOST	= 0x38,
    TWS_MR_SLA_ACK	= 0x40,
    TWS_MR_SLA_NACK	= 0x48,
    TWS_MR_DATA_ACK	= 0x50,
    TWS_MR_DATA_NACK	= 0x58
  };

  // Silly task to signal when a stop condition is completed.
  task void I2C_task() {
    loop_until_bit_is_clear(TWCR,TWSTO);
    signal I2C.sendEndDone();
  }


  command result_t StdControl.init() {
     // Set bit rate
    outb(TWBR,10);  // See Note, Page 205 of ATmega128 docs
    // Enable TWI interface and interrupts.
    outb(TWCR,((1 << TWINT) | (1 << TWEN) | (1 << TWIE)));

    state = 1;
    local_data = 0;
    return SUCCESS;
  }

  command result_t StdControl.start() {
    return SUCCESS;
  }

  command result_t StdControl.stop() {
    return SUCCESS;
  }

  command result_t I2C.sendStart() {
    // Direct TWI to send start condition.
    sbi(TWCR,TWSTA);
    sbi(TWCR,TWINT);

    return SUCCESS;
  }

  command result_t I2C.sendEnd() {
    // Direct TWI to send stop condition
    sbi(TWCR,TWSTO);
    sbi(TWCR,TWINT);

    post I2C_task();
    return SUCCESS;
  }

  // For reads and writes, if the TWINT bit is clear, the TWI is
  // busy or the TWI improperly initialized

  command result_t I2C.read(bool ack) {
    if (bit_is_clear(TWCR,TWINT))
        return FAIL;

    if (ack) 
      sbi(TWCR,TWEA);
    else
      cbi(TWCR,TWEA);

    sbi(TWCR,TWINT);  // Trigger the TWI

    return SUCCESS;
  }

  command result_t I2C.write(char data) {
    if(bit_is_clear(TWCR,TWINT)) 
        return FAIL;

    outb(TWDR,data);

    sbi(TWCR,TWINT);	// Trigger the TWI

    return SUCCESS;
  }

  default event result_t I2C.sendStartDone() {
    return SUCCESS;
  }

  default event result_t I2C.sendEndDone() {
    return SUCCESS;
  }

  default event result_t I2C.readDone(char data) {
    return SUCCESS;
  }

  default event result_t I2C.writeDone(bool success) {
    return SUCCESS;
  }

  TOSH_INTERRUPT(SIG_2WIRE_SERIAL) {

    switch (inb(TWSR) & 0xF8) {

    case TWS_BUSERROR:
      outb(TWCR,((1 << TWSTO) | (1 << TWINT)));  // Reset TWI
      break;

    case TWS_START: 
    case TWS_RSTART:
      signal I2C.sendStartDone();
      break;
      
    case TWS_MT_SLA_ACK:
    case TWS_MT_DATA_ACK:
      signal I2C.writeDone(TRUE);
      break;

    case TWS_MT_SLA_NACK:
    case TWS_MT_DATA_NACK:
      signal I2C.writeDone(FALSE);
      break;
      
    case TWS_MR_SLA_ACK:
      signal I2C.writeDone(TRUE);
      break;

    case TWS_MR_SLA_NACK:
      signal I2C.writeDone(FALSE);
      break;

    case TWS_MR_DATA_ACK:
    case TWS_MR_DATA_NACK:
      signal I2C.readDone(inb(TWDR));
      break;

    default:
      break;
    }
  } 
}