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- /*
- * max31855.c:
- * Extend wiringPi with the max31855 SPI Analog to Digital convertor
- * Copyright (c) 2012-2013 Gordon Henderson
- ***********************************************************************
- * This file is part of wiringPi:
- * https://projects.drogon.net/raspberry-pi/wiringpi/
- *
- * wiringPi is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * wiringPi is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with wiringPi.
- * If not, see <http://www.gnu.org/licenses/>.
- ***********************************************************************
- */
-
- #include <wiringPi.h>
- #include <wiringPiSPI.h>
-
- #include "max31855.h"
-
- /*
- * myAnalogRead:
- * Return the analog value of the given pin
- * Note: The chip really only has one read "channel", but we're faking it
- * here so we can read the error registers. Channel 0 will be the data
- * channel, and 1 is the error register code.
- * Note: Temperature returned is temp in C * 4, so divide result by 4
- *********************************************************************************
- */
-
- static int myAnalogRead (struct wiringPiNodeStruct *node, int pin)
- {
- unsigned int spiData ;
- int temp ;
- int chan = pin - node->pinBase ;
-
- wiringPiSPIDataRW (node->fd, (unsigned char *)&spiData, 4) ;
-
- if (chan == 0) // Read temp in C
- {
- spiData >>= 18 ;
- temp = spiData & 0x3FFF ; // Bottom 13 bits
- if ((spiData & 0x2000) != 0) // Negative
- temp = -temp ;
- return temp ;
- }
- else // Return error bits
- return spiData & 0x7 ;
- }
-
-
- /*
- * max31855Setup:
- * Create a new wiringPi device node for an max31855 on the Pi's
- * SPI interface.
- *********************************************************************************
- */
-
- int max31855Setup (const int pinBase, int spiChannel)
- {
- struct wiringPiNodeStruct *node ;
-
- if (wiringPiSPISetup (spiChannel, 5000000) < 0) // 5MHz - prob 4 on the Pi
- return -1 ;
-
- node = wiringPiNewNode (pinBase, 2) ;
-
- node->fd = spiChannel ;
- node->analogRead = myAnalogRead ;
-
- return 0 ;
- }
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