--- /dev/null
+/****************************************************************************
+ * extdrv/max31855_thermocouple.c
+ *
+ *
+ * Copyright 2015 Nathael Pajani <nathael.pajani@ed3l.fr>
+ *
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *************************************************************************** */
+
+#include <stdint.h>
+
+#include "core/lpc_regs_12xx.h"
+#include "core/system.h"
+#include "core/pio.h"
+#include "drivers/gpio.h"
+#include "drivers/ssp.h"
+#include "extdrv/max31855_thermocouple.h"
+
+/* Debug */
+#include "lib/stdio.h"
+
+
+/* Support for thermocouple temperature sensors using Maxim's MAX31855 themocouple
+ * to digital converter.
+ */
+
+
+
+/* Convert raw temperature data (expressed as ....)
+ * into a centimal integer value of ten times the actual temperature.
+ * The value returned is thus in tenth of celcius degrees.
+ */
+int max31855_convert_to_centi_degrees(uint16_t raw)
+{
+ uint16_t val16 = ((raw >> 2) & 0x07FF);
+ int val = 0;
+
+ if (raw & 0x2000) {
+ val16 = (~(val16) & 0x07FF);;
+ val = -val16;
+ val--;
+ } else {
+ val = val16;
+ }
+ val = val * 100;
+
+ val += (25 * (raw & 0x03));
+ return val;
+}
+
+/* Temp Read
+ * Performs a non-blocking read of the temperature from the sensor.
+ * 'raw' and 'centi_degrees' : integer addresses for conversion result, may be NULL.
+ * Return value(s):
+ * Upon successfull completion, returns 0 and the temperature read is placed in the integers pointed to
+ * by 'raw' and 'centi_degrees' pointers.
+ * Return -EBUSY when unable to get SPI bus mutex or -ENODEV if the Fault bit is set in the temperature
+ * word. If -ENODEV is returned and 'raw' is not NULL then raw will be updated with the three bits
+ * indicating the error condition instead of the temparature.
+ */
+int max31855_sensor_read(const struct max31855_sensor_config* conf, uint16_t* raw, int* centi_degrees)
+{
+ int temp = 0;
+ uint32_t data = 0;
+ uint16_t raw_temp = 0;
+
+ /* Get hold of the SPI bus */
+ if (spi_get_mutex(conf->ssp_bus_num) != 1) {
+ return -EBUSY;
+ }
+ /* Read data */
+ gpio_clear(conf->chip_select);
+ spi_transfer_multiple_frames(conf->ssp_bus_num, NULL, (uint8_t*)(&data), 4, 8);
+ gpio_set(conf->chip_select);
+ /* Release SPI bus */
+ spi_release_mutex(conf->ssp_bus_num);
+
+ /* Swap bytes ! */
+ data = byte_swap_32(data);
+
+ /* Check for fault info */
+ if (data & MAX31855_TH_FAULT) {
+ if (raw != NULL) {
+ *raw = (data & MAX31855_TH_ERROR_BITS_MASK);
+ }
+ return -ENODEV;
+ }
+
+ /* Convert result */
+ raw_temp = MAX31855_TH_TEMP_DATA(data);
+ temp = max31855_convert_to_centi_degrees(raw_temp);
+ if (raw != NULL) {
+ *raw = raw_temp;
+ }
+ if (centi_degrees != NULL) {
+ *centi_degrees = temp;
+ }
+
+ /* Debug */
+ uprintf(0, "TC: data(0x%08x) - raw(0x%04x) - deg: %d,%d\r\n", data, raw_temp, (temp / 100), (temp % 100));
+
+ return 0;
+}
+
+
+/* Sensor config */
+void max31855_sensor_config(const struct max31855_sensor_config* conf)
+{
+ /* Configure slave select pin as GPIO and set initial level to 1 (not selected) */
+ config_gpio(&(conf->chip_select), LPC_IO_MODE_PULL_UP, GPIO_DIR_OUT, 1);
+}
+
+
--- /dev/null
+/****************************************************************************
+ * extdrv/max31855_thermocouple.h
+ *
+ *
+ * Copyright 2012 Nathael Pajani <nathael.pajani@ed3l.fr>
+ *
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *************************************************************************** */
+
+#ifndef EXTDRV_MAX31855_H
+#define EXTDRV_MAX31855_H
+
+#include <stdint.h>
+#include "core/pio.h"
+
+/* Support for thermocouple temperature sensors using Maxim's MAX31855 themocouple
+ * to digital converter.
+ */
+
+struct max31855_sensor_config {
+ uint8_t ssp_bus_num;
+ struct pio chip_select;
+};
+
+#define MAX31855_TH_TEMP_DATA(x) (((x) >> 18) & 0x3FFF)
+#define MAX31855_TH_REF_DATA(x) (((x) >> 4) & 0x0FFF)
+#define MAX31855_TH_FAULT (0x01 << 16)
+#define MAX31855_TH_ERROR_BITS_MASK (0x07)
+#define MAX31855_TH_ERR_SHORT_TO_VCC (0x01 << 2)
+#define MAX31855_TH_ERR_SHORT_TO_GND (0x01 << 1)
+#define MAX31855_TH_ERR_OPEN_CIRCUIT (0x01 << 0)
+
+/* Convert raw temperature data (expressed as ....)
+ * into a decimal integer value of ten times the actual temperature.
+ * The value returned is thus in tenth of celcius degrees.
+ */
+int max31855_convert_to_deci_degrees(uint16_t raw);
+
+/* Temp Read
+ * Performs a non-blocking read of the temperature from the sensor.
+ * 'raw' and 'deci_degrees' : integer addresses for conversion result, may be NULL.
+ * Return value(s):
+ * Upon successfull completion, returns 0 and the temperature read is placed in the
+ * integers pointed to by 'raw' and 'deci_degrees' pointers.
+ */
+int max31855_sensor_read(const struct max31855_sensor_config* conf, uint16_t* raw, int* deci_degrees);
+
+/* Sensor config */
+void max31855_sensor_config(const struct max31855_sensor_config* conf);
+
+
+#endif /* EXTDRV_MAX31855_H */
+
