contiki/platform/z1/dev/tmp102.c
Matthieu Baerts 78b6b50194 Z1: tmp102: simple: fixed wrong cast
When using this code:

    (int8_t)tmp102_read_temp_x100() / 100

Only the first value is casted into a int8_t type.

tmp102_read_temp_x100() returns the temperature in Celcius * 100. Most of
the time this value will be lower than -2^7 and higher than 2^7 (+/- 1.27°C).

The cast is not needed but a comment about this implicit cast has been added.
2015-05-22 18:15:26 +02:00

191 lines
5.8 KiB
C

/*
* 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
* Device drivers for tmp102 temperature sensor in Zolertia Z1.
* \author
* Enric M. Calvo, Zolertia <ecalvo@zolertia.com>
* Marcus Lundén, SICS <mlunden@sics.se>
*/
#include <stdio.h>
#include "contiki.h"
#include "i2cmaster.h"
#include "tmp102.h"
/* Bitmasks and bit flag variable for keeping track of tmp102 status. */
enum TMP102_STATUSTYPES {
/* must be a bit and not more, not using 0x00. */
INITED = 0x01,
RUNNING = 0x02,
STOPPED = 0x04,
LOW_POWER = 0x08,
AAA = 0x10, /* available to extend this... */
BBB = 0x20, /* available to extend this... */
CCC = 0x40, /* available to extend this... */
DDD = 0x80 /* available to extend this... */
};
static enum TMP102_STATUSTYPES _TMP102_STATUS = 0x00;
/*---------------------------------------------------------------------------*/
/* PROCESS(tmp102_process, "Temperature Sensor process"); */
/*---------------------------------------------------------------------------*/
/* Init the temperature sensor: ports, pins, registers, interrupts (none enabled), I2C,
default threshold values etc. */
void
tmp102_init(void)
{
if(!(_TMP102_STATUS & INITED)) {
PRINTFDEBUG("TMP102 init\n");
_TMP102_STATUS |= INITED;
/* Power Up TMP102 via pin */
TMP102_PWR_DIR |= TMP102_PWR_PIN;
TMP102_PWR_SEL &= ~TMP102_PWR_SEL;
TMP102_PWR_SEL2 &= ~TMP102_PWR_SEL;
TMP102_PWR_REN &= ~TMP102_PWR_SEL;
TMP102_PWR_OUT |= TMP102_PWR_PIN;
/* Set up ports and pins for I2C communication */
i2c_enable();
}
}
/*---------------------------------------------------------------------------*/
/* Write to a 16-bit register.
args:
reg register to write to
val value to write
*/
void
tmp102_write_reg(uint8_t reg, uint16_t val)
{
uint8_t tx_buf[] = { reg, 0x00, 0x00 };
tx_buf[1] = (uint8_t)(val >> 8);
tx_buf[2] = (uint8_t)(val & 0x00FF);
i2c_transmitinit(TMP102_ADDR);
while(i2c_busy());
PRINTFDEBUG("I2C Ready to TX\n");
i2c_transmit_n(3, tx_buf);
while(i2c_busy());
PRINTFDEBUG("WRITE_REG 0x%04X @ reg 0x%02X\n", val, reg);
}
/*---------------------------------------------------------------------------*/
/* Read register.
args:
reg what register to read
returns the value of the read register type uint16_t
*/
uint16_t
tmp102_read_reg(uint8_t reg)
{
uint8_t buf[] = { 0x00, 0x00 };
uint16_t retVal = 0;
uint8_t rtx = reg;
PRINTFDEBUG("READ_REG 0x%02X\n", reg);
/* transmit the register to read */
i2c_transmitinit(TMP102_ADDR);
while(i2c_busy());
i2c_transmit_n(1, &rtx);
while(i2c_busy());
/* receive the data */
i2c_receiveinit(TMP102_ADDR);
while(i2c_busy());
i2c_receive_n(2, &buf[0]);
while(i2c_busy());
retVal = (uint16_t)(buf[0] << 8 | (buf[1]));
return retVal;
}
/*---------------------------------------------------------------------------*/
/* Read temperature in a raw format. Further processing will be needed
to make an interpretation of these 12 or 13-bit data, depending on configuration
*/
uint16_t
tmp102_read_temp_raw(void)
{
uint16_t rd = 0;
rd = tmp102_read_reg(TMP102_TEMP);
return rd;
}
int16_t
tmp102_read_temp_x100(void)
{
int16_t raw = 0;
int16_t sign = 1;
int16_t abstemp, temp_int;
raw = (int16_t)tmp102_read_reg(TMP102_TEMP);
if(raw < 0) {
abstemp = (raw ^ 0xFFFF) + 1;
sign = -1;
} else {
abstemp = raw;
}
/* Integer part of the temperature value and percents*/
temp_int = (abstemp >> 8) * sign * 100;
temp_int += ((abstemp & 0xff) * 100) / 0x100;
/* See test-tmp102.c on how to print values of temperature with decimals
fractional part in 1/10000 of degree
temp_frac = ((abstemp >>4) % 16) * 625;
Data could be multiplied by 63 to have less bit-growth and 1/1000 precision
Data could be multiplied by 64 (<< 6) to trade-off precision for speed
*/
return temp_int;
}
/*---------------------------------------------------------------------------*/
/* Simple Read temperature. Return is an integer with temperature in 1deg. precision
Return value is a signed 8 bit integer.
*/
int8_t
tmp102_read_temp_simple(void)
{
/* Casted to int8_t: We don't expect temperatures outside -128 to 127 C */
return tmp102_read_temp_x100() / 100;
}