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contiki/core/dev/sht11.c

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/*
* Copyright (c) 2007, 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.
*
* @(#)$Id: sht11.c,v 1.3 2008/11/10 21:10:36 adamdunkels Exp $
*/
/*
* Device driver for the Sensirion SHT1x/SHT7x family of humidity and
* temperature sensors.
*/
#include "contiki.h"
#include <stdio.h>
#ifdef __IAR_SYSTEMS_ICC__
#include <msp430.h>
#else
#include <io.h>
#include <signal.h>
#endif
#include <dev/sht11.h>
#include "sht11-arch.h"
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
#ifndef SDA_0
#define SDA_0() (SHT11_PxDIR |= BV(SHT11_ARCH_SDA)) /* SDA Output=0 */
#define SDA_1() (SHT11_PxDIR &= ~BV(SHT11_ARCH_SDA)) /* SDA Input */
#define SDA_IS_1 (SHT11_PxIN & BV(SHT11_ARCH_SDA))
#define SCL_0() (SHT11_PxOUT &= ~BV(SHT11_ARCH_SCL)) /* SCL Output=0 */
#define SCL_1() (SHT11_PxOUT |= BV(SHT11_ARCH_SCL)) /* SCL Output=1 */
#endif
/* adr command r/w */
#define STATUS_REG_W 0x06 /* 000 0011 0 */
#define STATUS_REG_R 0x07 /* 000 0011 1 */
#define MEASURE_TEMP 0x03 /* 000 0001 1 */
#define MEASURE_HUMI 0x05 /* 000 0010 1 */
#define RESET 0x1e /* 000 1111 0 */
/* This can probably be reduced to 250ns according to data sheet. */
#ifndef delay_400ns
#define delay_400ns() _NOP()
#endif
/*---------------------------------------------------------------------------*/
static void
sstart(void)
{
SDA_1(); SCL_0();
delay_400ns();
SCL_1();
delay_400ns();
SDA_0();
delay_400ns();
SCL_0();
delay_400ns();
SCL_1();
delay_400ns();
SDA_1();
delay_400ns();
SCL_0();
}
/*---------------------------------------------------------------------------*/
static void
sreset(void)
{
int i;
SDA_1();
SCL_0();
for(i = 0; i < 9 ; i++) {
SCL_1();
delay_400ns();
SCL_0();
delay_400ns();
}
sstart(); /* Start transmission, why??? */
}
/*---------------------------------------------------------------------------*/
/*
* Return true if we received an ACK.
*/
static int
swrite(unsigned _c)
{
unsigned char c = _c;
int i;
int ret;
for(i = 0; i < 8; i++, c <<= 1) {
if(c & 0x80) {
SDA_1();
} else {
SDA_0();
}
SCL_1();
delay_400ns();
SCL_0();
delay_400ns();
}
SDA_1();
SCL_1();
delay_400ns();
ret = !SDA_IS_1;
SCL_0();
return ret;
}
/*---------------------------------------------------------------------------*/
static unsigned
sread(int send_ack)
{
int i;
unsigned char c = 0x00;
SDA_1();
for(i = 0; i < 8; i++) {
c <<= 1;
SCL_1();
delay_400ns();
if(SDA_IS_1) {
c |= 0x1;
}
SCL_0();
delay_400ns();
}
if(send_ack) {
SDA_0();
}
SCL_1();
delay_400ns();
SCL_0();
SDA_1(); /* Release SDA */
return c;
}
/*---------------------------------------------------------------------------*/
#define CRC_CHECK
#ifdef CRC_CHECK
static unsigned char
rev8bits(unsigned char v)
{
unsigned char r = v;
int s = 7;
for (v >>= 1; v; v >>= 1) {
r <<= 1;
r |= v & 1;
s--;
}
r <<= s; /* Shift when v's highest bits are zero */
return r;
}
/*---------------------------------------------------------------------------*/
/* BEWARE: Bit reversed CRC8 using polynomial ^8 + ^5 + ^4 + 1 */
static unsigned
crc8_add(unsigned acc, unsigned byte)
{
int i;
acc ^= byte;
for(i = 0; i < 8; i++) {
if(acc & 0x80) {
acc = (acc << 1) ^ 0x31;
} else {
acc <<= 1;
}
}
return acc & 0xff;
}
#endif /* CRC_CHECK */
/*---------------------------------------------------------------------------*/
/*
* Power up the device. The device can be used after an additional
* 11ms waiting time.
*/
void
sht11_init(void)
{
/*
* SCL Output={0,1}
* SDA 0: Output=0
* 1: Input and pull-up (Output=0)
*/
#ifdef SHT11_INIT
SHT11_INIT();
#else
SHT11_PxOUT |= BV(SHT11_ARCH_PWR);
SHT11_PxOUT &= ~(BV(SHT11_ARCH_SDA) | BV(SHT11_ARCH_SCL));
SHT11_PxDIR |= BV(SHT11_ARCH_PWR) | BV(SHT11_ARCH_SCL);
#endif
}
/*---------------------------------------------------------------------------*/
/*
* Power of device.
*/
void
sht11_off(void)
{
#ifdef SHT11_OFF
SHT11_OFF();
#else
SHT11_PxOUT &= ~BV(SHT11_ARCH_PWR);
SHT11_PxOUT &= ~(BV(SHT11_ARCH_SDA) | BV(SHT11_ARCH_SCL));
SHT11_PxDIR |= BV(SHT11_ARCH_PWR) | BV(SHT11_ARCH_SCL);
#endif
}
/*---------------------------------------------------------------------------*/
/*
* Only commands MEASURE_HUMI or MEASURE_TEMP!
*/
static unsigned int
scmd(unsigned cmd)
{
unsigned long n;
if(cmd != MEASURE_HUMI && cmd != MEASURE_TEMP) {
PRINTF("Illegal command: %d\n", cmd);
return -1;
}
sstart(); /* Start transmission */
if(!swrite(cmd)) {
PRINTF("SHT11: scmd - swrite failed\n");
goto fail;
}
for(n = 0; n < 250000; n++) {
if(!SDA_IS_1) {
unsigned t0, t1, rcrc;
t0 = sread(1);
t1 = sread(1);
rcrc = sread(0);
PRINTF("SHT11: scmd - read %d, %d\n", t0, t1);
#ifdef CRC_CHECK
{
unsigned crc;
crc = crc8_add(0x0, cmd);
crc = crc8_add(crc, t0);
crc = crc8_add(crc, t1);
if(crc != rev8bits(rcrc)) {
PRINTF("SHT11: scmd - crc check failed %d vs %d\n",
crc, rev8bits(rcrc));
goto fail;
}
}
#endif
return (t0 << 8) | t1;
}
}
fail:
sreset();
return -1;
}
/*---------------------------------------------------------------------------*/
/*
* Call may take up to 210ms.
*/
unsigned int
sht11_temp(void)
{
return scmd(MEASURE_TEMP);
}
/*---------------------------------------------------------------------------*/
/*
* Call may take up to 210ms.
*/
unsigned int
sht11_humidity(void)
{
return scmd(MEASURE_HUMI);
}
/*---------------------------------------------------------------------------*/
#if 1 /* But ok! */
unsigned
sht11_sreg(void)
{
unsigned sreg, rcrc;
sstart(); /* Start transmission */
if(!swrite(STATUS_REG_R)) {
goto fail;
}
sreg = sread(1);
rcrc = sread(0);
#ifdef CRC_CHECK
{
unsigned crc;
crc = crc8_add(0x0, STATUS_REG_R);
crc = crc8_add(crc, sreg);
if (crc != rev8bits(rcrc))
goto fail;
}
#endif
return sreg;
fail:
sreset();
return -1;
}
#endif
/*---------------------------------------------------------------------------*/
#if 0
int
sht11_set_sreg(unsigned sreg)
{
sstart(); /* Start transmission */
if(!swrite(STATUS_REG_W)) {
goto fail;
}
if(!swrite(sreg)) {
goto fail;
}
return 0;
fail:
sreset();
return -1;
}
#endif
/*---------------------------------------------------------------------------*/
#if 0
int
sht11_reset(void)
{
sstart(); /* Start transmission */
if(!swrite(RESET)) {
goto fail;
}
return 0;
fail:
sreset();
return -1;
}
#endif
/*---------------------------------------------------------------------------*/
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