244 lines
7.2 KiB
C
244 lines
7.2 KiB
C
/*
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* Copyright (c) 2009, University of Colombo School of Computing
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/*
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* Device driver for the Dallas Semiconductor DS2401 chip. Heavily
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* based on the application note 126 "1-Wire Communications Through
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* Software".
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*
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* http://www.maxim-ic.com/appnotes.cfm/appnote_number/126
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*/
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/*
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* For now we stuff in Crossbow Technology, Inc's unique OUI.
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* 00:1A:4C Crossbow Technology, Inc
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*
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* The EUI-64 is a concatenation of the 24-bit OUI value assigned by
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* the IEEE Registration Authority and a 40-bit extension identifier
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* assigned by the organization with that OUI assignment.
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*/
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#include <avr/io.h>
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#include <string.h>
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#include "contiki.h"
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#include "ds2401.h"
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unsigned char ds2401_id[8];
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/* 1-wire is at PortA.4 */
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#define SERIAL_ID_PIN_READ PINA
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#define SERIAL_ID_PIN_MASK _BV(4)
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#define SERIAL_ID_PxOUT PORTA
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#define SERIAL_ID_PxDIR DDRA
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#define SET_PIN_INPUT() (SERIAL_ID_PxDIR &= ~SERIAL_ID_PIN_MASK)
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#define SET_PIN_OUTPUT() (SERIAL_ID_PxDIR |= SERIAL_ID_PIN_MASK)
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#define OUTP_0() (SERIAL_ID_PxOUT &= ~SERIAL_ID_PIN_MASK)
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#define OUTP_1() (SERIAL_ID_PxOUT |= SERIAL_ID_PIN_MASK)
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#define PIN_INIT() do{ \
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SET_PIN_INPUT(); \
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OUTP_0(); \
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} while(0)
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/* Drive the one wire interface low */
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#define OW_DRIVE() do { \
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SET_PIN_OUTPUT(); \
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OUTP_0(); \
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} while (0)
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/* Release the one wire by turning on the internal pull-up. */
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#define OW_RELEASE() do { \
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SET_PIN_INPUT(); \
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OUTP_1(); \
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} while (0)
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/* Read one bit. */
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#define INP() (SERIAL_ID_PIN_READ & SERIAL_ID_PIN_MASK)
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/*
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* Delay times in us.
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*/
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#define tA 6 /* min-5, recommended-6, max-15 */
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#define tB 64 /* min-59, recommended-64, max-N/A */
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#define tC 60 /* min-60, recommended-60, max-120 */
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#define tD 10 /* min-5.3, recommended-10, max-N/A */
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#define tE 9 /* min-0.3, recommended-9, max-9.3 */
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#define tF 55 /* min-50, recommended-55, max-N/A */
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#define tG 0 /* min-0, recommended-0, max-0 */
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#define tH 480 /* min-480, recommended-480, max-640 */
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#define tI 70 /* min-60.3, recommended-70, max-75.3 */
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#define tJ 410 /* min-410, recommended-410, max-N/A */
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/*---------------------------------------------------------------------------*/
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/*
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* The delay caused by calling the delay_loop is given by the following
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* formula.
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* delay(us) = (4n + 1)/XTAL
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* where n is the number of iterations and XTAL is the clock frequency(in MHz).
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* TODO: Moving the delay_loop to dev/clock.c
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*/
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static void
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delay_loop(uint16_t __count)
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{
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asm volatile ("1: sbiw %0,1" "\n\t"
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"brne 1b"
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: "=w" (__count)
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: "0" (__count)
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);
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}
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/*---------------------------------------------------------------------------*/
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/*
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* This macro relies on the compiler doing the arithmetic during compile time
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* for the needed iterations.!!
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* In MICAz, XTAL = 7.3728 MHz
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*/
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#define udelay(u) delay_loop(((7.3728F * u)-1)/4)
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/*---------------------------------------------------------------------------*/
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static uint8_t
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reset(void)
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{
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uint8_t result;
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OW_DRIVE();
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udelay(500); /* 480 < tH < 640 */
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OW_RELEASE(); /* Releases the bus */
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udelay(tI);
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result = INP();
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udelay(tJ);
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return result;
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}
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/*---------------------------------------------------------------------------*/
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static void
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write_byte(uint8_t byte)
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{
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uint8_t i = 7;
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do {
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if (byte & 0x01) {
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OW_DRIVE();
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udelay(tA);
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OW_RELEASE(); /* Releases the bus */
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udelay(tB);
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} else {
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OW_DRIVE();
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udelay(tC);
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OW_RELEASE(); /* Releases the bus */
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udelay(tD);
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}
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if (i == 0)
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return;
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i--;
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byte >>= 1;
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} while (1);
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}
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/*---------------------------------------------------------------------------*/
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static unsigned
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read_byte(void)
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{
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unsigned result = 0;
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int i = 7;
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do {
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OW_DRIVE();
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udelay(tA);
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OW_RELEASE(); /* Releases the bus */
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udelay(tE);
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if (INP())
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result |= 0x80; /* LSbit first */
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udelay(tF);
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if (i == 0)
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return result;
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i--;
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result >>= 1;
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} while (1);
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}
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/*---------------------------------------------------------------------------*/
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/* Polynomial ^8 + ^5 + ^4 + 1 */
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static unsigned
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crc8_add(unsigned acc, unsigned byte)
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{
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int i;
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acc ^= byte;
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for (i = 0; i < 8; i++)
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if (acc & 1)
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acc = (acc >> 1) ^ 0x8c;
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else
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acc >>= 1;
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return acc;
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}
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/*---------------------------------------------------------------------------*/
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int
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ds2401_init()
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{
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int i;
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uint8_t volatile sreg;
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unsigned family, crc, acc;
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PIN_INIT();
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sreg = SREG; /* Save status register before disabling interrupts. */
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cli(); /* Disable interrupts. */
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if (reset() == 0) {
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write_byte(0x33); /* Read ROM command. */
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family = read_byte();
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for (i = 7; i >= 2; i--) {
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ds2401_id[i] = read_byte();
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}
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crc = read_byte();
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SREG = sreg; /* Enable interrupts. */
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if(family != 0x01) {
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goto fail;
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}
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acc = crc8_add(0x0, family);
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for (i = 7; i >= 2; i--) {
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acc = crc8_add(acc, ds2401_id[i]);
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}
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if (acc == crc) {
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/* 00:1A:4C OUI for Crossbow Technology, Inc. */
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ds2401_id[0] = 0x00;
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ds2401_id[1] = 0x1A;
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ds2401_id[2] = 0x4C;
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return 1; /* Success! */
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}
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} else {
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SREG = sreg; /* Enable interrupts. */
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}
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fail:
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memset(ds2401_id, 0x0, sizeof(ds2401_id));
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return 0; /* Fail! */
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}
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/*---------------------------------------------------------------------------*/
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