36be22cb90
* Made CMake depend on 0.4 libmraa Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>
104 lines
2.8 KiB
C++
104 lines
2.8 KiB
C++
/*
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* Author: Brendan Le Foll <brendan.le.foll@intel.com>
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* Copyright (c) 2014 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <iostream>
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#include <unistd.h>
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#include <stdlib.h>
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#include <functional>
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#include <string.h>
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#include "max31855.h"
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using namespace upm;
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//! [Constructor]
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MAX31855::MAX31855(int bus, int cs)
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{
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// initialise chip select as a normal gpio
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m_gpio = mraa_gpio_init(cs);
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mraa_gpio_dir(m_gpio, MRAA_GPIO_OUT);
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// initialise the spi bus with a 2Mhz clock
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m_sensor = mraa_spi_init(bus);
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mraa_spi_frequency(m_sensor, 2000000);
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}
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//! [Constructor]
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//! [Destructor]
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MAX31855::~MAX31855()
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{
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// close both m_sensor & m_gpio cleanly
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mraa_result_t error;
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error = mraa_spi_stop(m_sensor);
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if (error != MRAA_SUCCESS) {
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mraa_result_print(error);
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}
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error = mraa_gpio_close(m_gpio);
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if (error != MRAA_SUCCESS) {
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mraa_result_print(error);
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}
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}
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//! [Destructor]
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double
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MAX31855::getTemp()
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{
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//! [spi]
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// set chip select low
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mraa_gpio_write(m_gpio, 0);
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uint8_t buf[4];
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// set our input buffer to 0, this is clean but not required
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memset(buf, 0, sizeof(uint8_t)*4);
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// Write buffer to the spi slave
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uint8_t* x = mraa_spi_write_buf(m_sensor, buf, 4);
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//! [spi]
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//! [conversion]
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// Endian correct way of making our char array into an 32bit int
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int32_t temp = (x[0] << 24) | (x[1] << 16) | (x[2] << 8) | x[3];;
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// mraa_spi_write_buf does not free the return buffer
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free(x);
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if (temp & 0x7) {
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std::cerr << "Something went very wrong!" << std::endl;
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}
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// scrap all the data we dont care about
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temp >>= 18;
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// LSB = 0.25 degrees C
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double c = (double) temp;
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c *= 0.25;
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//! [conversion]
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// set chip select high
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mraa_gpio_write(m_gpio, 1);
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return c;
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}
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