add read function

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required(VERSION 3.13)
 # note: this must happen before project()
 include(libs/pico-sdk/pico_sdk_init.cmake)
 
-project(my_project)
+project(temp_sensor)
 
 # initialize the Raspberry Pi Pico SDK
 pico_sdk_init()

src/max31856.c

@@ -1,5 +1,6 @@
 #include "pico/stdlib.h"
 #include "hardware/spi.h"
+#include <stdint.h>
 
 #include "max31856.h"
 
@@ -45,3 +46,33 @@ int max31856_write8(max31856_t *max, uint8_t addr, uint8_t value)
 
    return 0;
 }
+
+uint8_t max31856_read8(max31856_t *max, uint8_t addr)
+{
+   if (!(max->initilzed))
+   {
+      return -1;
+   }
+   const uint16_t buff_tx = (addr & 0x7F)<<8;
+   const uint8_t buff_rx[] = {0, 0};
+   gpio_put(max->pin_cs, 0);
+   spi_read_blocking(SPI_MAX31856, buff_tx, &buff_rx[0], 2);
+   gpio_put(max->pin_cs, 1);
+
+   return buff_rx[1];
+}
+
+uint16_t max31856_read16(max31856_t *max, uint8_t addr)
+{
+   if (!(max->initilzed))
+   {
+      return -1;
+   }
+   const uint16_t buff_tx = (addr & 0x7F)<<8;
+   const uint8_t buff_rx[] = {0, 0, 0};
+   gpio_put(max->pin_cs, 0);
+   spi_read_blocking(SPI_MAX31856, buff_tx, &buff_rx[0], 3);
+   gpio_put(max->pin_cs, 1);
+
+   return buff_rx[1]<<8 | buff_rx[2];
+}

src/max31856.h

@@ -12,6 +12,7 @@ typedef struct max31856_s {
 void max31856_init(max31856_t *max);
 void max31856_deinit(max31856_t *max);
 int max31856_write8(max31856_t *max, uint8_t addr, uint8_t value);
+uint16_t max31856_read16(max31856_t *max, uint8_t addr);
 
 #define MAX31856_REG_CR0    0x00
 #define MAX31856_REG_CR0_CMODE      0x80