MAX31855 library
Fork of MAX31855 by
MAX31855.cpp
- Committer:
- DanielBlomdahl
- Date:
- 2016-03-10
- Revision:
- 1:d8234681d212
- Parent:
- 0:5d56064bc4c3
File content as of revision 1:d8234681d212:
/* * A library for MAX31855 * * Copyright (c) 2015 Seeed Technology Limited. * Author : Yihui Xiong * * The MIT License (MIT) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "MAX31855.h" #define LOG(args...) printf(args) MAX31855::MAX31855(SPI& _spi, PinName _ncs) : spi(_spi), ncs(_ncs) { thermocoupleT = 0.0 / 0.0; internalT = 0.0 / 0.0; lastReadTime = 0; } float MAX31855::read(temperature_type_t type) { uint8_t buf[4]; uint32_t time = us_ticker_read(); uint32_t duration = time - lastReadTime; if (duration > 250000) { // more than 250ms //Set CS low to start transmission (interrupts conversion) ncs = 0; //Read in Probe tempeature for (int i = 0; i < 4; i++) { buf[i] = spi.write(0); } //Set CS high to stop transmission (restarts conversion) ncs = 1; if (buf[1] & 1) { uint8_t fault = buf[3] & 0x7; if (fault & 0x1) { LOG("The thermocouple is open (no connections).\r\n"); } if (fault & 0x2) { LOG("The thermocouple is short-circuited to GND.\r\n"); } if (fault & 0x4) { LOG("The thermocouple is short-circuited to VCC.\r\n"); } return 0.0 / 0.0; } int t1 = ((buf[0] & 0x7F) << 6) + (buf[1] >> 2); if (buf[0] & 0x80) { // sign bit t1 = -t1; } thermocoupleT = t1 * 0.25; int t2 = ((buf[2] & 0x7F) << 4) + (buf[3] >> 4); if (buf[2] & 0x80) { t2 = -t2; } internalT = t2 * 0.0625; } if (THERMOCOUPLE_T == type) { return thermocoupleT; } else { return internalT; } }