contiki/platform/wismote/dev/sht15.c

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/* Copyright (c) 2009 ARAGO SYSTEMS
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* Neither the name of the copyright holders nor the names of
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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: v 0.1 2011/02/15 tchapelle Exp $
*/
#include "dev/sht15.h"
/***********************************************************************************
* @fn halMcuWaitUs
*
* @brief Busy wait function. Waits the specified number of microseconds. Use
* assumptions about number of clock cycles needed for the various
* instructions. The duration of one cycle depends on MCLK. In this HAL
* , it is set to 8 MHz, thus 8 cycles per usec.
*
* NB! This function is highly dependent on architecture and compiler!
*
* @param uint16 usec - number of microseconds delay
*
* @return none
*/
/* #pragma optimize=none */
void halMcuWaitUs(uint16_t usec) // 5 cycles for calling
{
// The least we can wait is 3 usec:
// ~1 usec for call, 1 for first compare and 1 for return
while(usec > 3) // 2 cycles for compare
{ // 2 cycles for jump
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
nop(); // 1 cycles for nop
usec -= 2; // 1 cycles for optimized decrement
}
} // 4 cycles for returning
/**
SHT15/75 Driver
!!! be advise that the SHT15 and SHT75 are not i2C compliant sensors
they are just designed to not disturb i2C devices on a 2 wire bus
this driver allow to drive the sensor with GPIO and delay
*/
/***********************************************************************************
* @fn sht15_send_start
*
* @brief This function perform the start sequence asked by SHT15 and SHT75
*
*
*
* @param none
*
* @return none
*/
void sht15_send_start()
{
// Sequence is to set data line to 1 then clock line to 1
// then set data line to 0, clock line to 0
// then set clock line to 1 and data line to 1
// ___________ ________
// data line : _____/ \___________/
// ___________ ____________
// clock line : _________/ \___/
DATA_OUT();
DATA_SET();
SCK_SET();
DATA_CLR();
SCK_CLR();
SCK_SET();
DATA_SET();
SCK_CLR();
}
/***********************************************************************************
* @fn sht15_read16()
*
* @brief
*
*
*
* @param none
*
* @return uint16_t
*/
uint16_t sht15_read16()
{
uint16_t i;
DATA_IN();
SCK_CLR();
uint16_t val = 0;
for(i = 0; i < 18; i++)
{
if((i != 8) && (i != 17))
{
SCK_SET();
if(DATA_VAL())
val |= 1;
val <<= 1;
SCK_CLR();
}
else if(i == 8) // Wait for first ACK from SHT15
{
DATA_OUT();
DATA_CLR();
SCK_SET();
SCK_CLR();
DATA_IN();
}
else if(i == 17) // Wait for second ACK from SHT15
{
DATA_OUT();
DATA_SET();
SCK_SET();
SCK_CLR();
}
}
return val;
}
/***********************************************************************************
* @fn sht15_write8
*
* @brief
*
*
*
* @param uint8 val
*
* @return none
*/
void sht15_write8(uint8_t val)
{
uint16_t i;
DATA_OUT();
for(i = 0; i < 8; i++)
{
halMcuWaitUs(4);
SCK_CLR();
if(val & 0x80)
{
DATA_SET();
}
else
{
DATA_CLR();
}
val <<= 1;
SCK_SET();
}
DATA_IN();
SCK_CLR();
while(DATA_VAL());
SCK_SET();
SCK_CLR();
}
/***********************************************************************************
* @fn sht15_wait_measure
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_wait_measure()
{
while(DATA_VAL());
}
/***********************************************************************************
* @fn sht15_init
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_init()
{
// DATA and SCK lines are I/O
P3SEL &= ~BIT7;
P5SEL &= ~BIT4;
// Set SCK and DATA as output
DATA_OUT();
SCK_OUT();
DATA_SET();
SCK_SET();
}
/***********************************************************************************
* @fn sht15_measure_temp
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_measure_temp()
{
sht15_send_start();
sht15_write8(3);
}
/***********************************************************************************
* @fn sht15_measure_hum
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_measure_hum()
{
sht15_send_start();
sht15_write8(5);
}
/***********************************************************************************
* @fn sht15_read_status
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_read_status()
{
sht15_send_start();
sht15_write8(7);
}
/***********************************************************************************
* @fn sht15_write_status
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_write_status()
{
sht15_send_start();
sht15_write8(6);
}
/***********************************************************************************
* @fn sht15_soft_reset
*
* @brief
*
*
*
* @param none
*
* @return none
*/
void sht15_soft_reset()
{
sht15_send_start();
sht15_write8(30);
}