diff --git a/CMakeLists.txt b/CMakeLists.txt
index 39b3bbe..a497d6d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,10 +11,11 @@ pico_sdk_init()
 
 add_executable(my_project
     src/main.c
+    src/max31856.c
 )
 
 # Add pico_stdlib library which aggregates commonly used features
-target_link_libraries(my_project pico_stdlib)
+target_link_libraries(my_project pico_stdlib hardware_spi)
 
 # create map/bin/hex/uf2 file in addition to ELF.
 pico_add_extra_outputs(my_project)
diff --git a/libs/pico-sdk b/libs/pico-sdk
new file mode 160000
index 0000000..6a7db34
--- /dev/null
+++ b/libs/pico-sdk
@@ -0,0 +1 @@
+Subproject commit 6a7db34ff63345a7badec79ebea3aaef1712f374
diff --git a/src/main.c b/src/main.c
index 411626b..58fa0e3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,35 +1,64 @@
 #include <stdio.h>
 #include "pico/stdlib.h"
 
+#include "max31856.h"
+
 // pin rgb led on Seeed XIAO RP2040
 #define PIN_RGB_R 17
 #define PIN_RGB_G 16
 #define PIN_RGB_B 25
 
-int main() {
-  setup_default_uart();
-  printf("Hello, world!\n");
+max31856_t temp[2];
 
+void init_rbg()
+{
   gpio_init(PIN_RGB_R);
   gpio_set_dir(PIN_RGB_R, GPIO_OUT);
   gpio_init(PIN_RGB_G);
   gpio_set_dir(PIN_RGB_G, GPIO_OUT);
   gpio_init(PIN_RGB_B);
   gpio_set_dir(PIN_RGB_B, GPIO_OUT);
+}
+
+void rgb_rainbow()
+{
+  gpio_put(PIN_RGB_G, 1);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_R, 0);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_B, 1);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_G, 0);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_R, 1);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_B, 0);
+  sleep_ms(250);
+  gpio_put(PIN_RGB_R, 0);
+}
+
+int main() {
+  setup_default_uart();
+  printf("Hello, world!\n");
+
+  init_rbg();
+  rgb_rainbow();
+
+  // init temp sensors
+  temp[0].pin_cs = 4;
+  max31856_init(&(temp[0]));
+  temp[1].pin_cs = 5;
+  max31856_init(&(temp[1]));
+  // config temp sensor 0
+  max31856_write8(&(temp[0]), MAX31856_REG_CR0, MAX31856_REG_CR0_CMODE | /*MAX31856_REG_CR0_OCFAULT |*/ MAX31856_REG_CR0_50HZ);
+  max31856_write8(&(temp[0]), MAX31856_REG_CR1, MAX31856_REG_CR1_AVGSEL_1 | MAX31856_REG_CR1_TC_TYPE_K);
+  // config temp sensor 1
+  max31856_write8(&(temp[1]), MAX31856_REG_CR0, MAX31856_REG_CR0_CMODE | /*MAX31856_REG_CR0_OCFAULT |*/ MAX31856_REG_CR0_50HZ);
+  max31856_write8(&(temp[1]), MAX31856_REG_CR1, MAX31856_REG_CR1_AVGSEL_1 | MAX31856_REG_CR1_TC_TYPE_K);
+
   while (true)
   {
-    gpio_put(PIN_RGB_G, 1);
-    sleep_ms(250);
-    gpio_put(PIN_RGB_R, 0);
-    sleep_ms(250);
-    gpio_put(PIN_RGB_B, 1);
-    sleep_ms(250);
-    gpio_put(PIN_RGB_G, 0);
-    sleep_ms(250);
-    gpio_put(PIN_RGB_R, 1);
-    sleep_ms(250);
-    gpio_put(PIN_RGB_B, 0);
-    sleep_ms(250);
+    rgb_rainbow();
   }
   return 0;
 }
diff --git a/src/max31856.c b/src/max31856.c
new file mode 100644
index 0000000..f88188c
--- /dev/null
+++ b/src/max31856.c
@@ -0,0 +1,47 @@
+#include "pico/stdlib.h"
+#include "hardware/spi.h"
+
+#include "max31856.h"
+
+// max31856 pins
+#define SPI_MAX31856            spi0
+#define SPI_MAX31856_BOUD       1E6 // 1 MHz (max31856 can go up to 5 MHz)
+#define SPI_MAX31856_SPO        SPI_CPOL_0
+#define SPI_MAX31856_SPH        SPI_CPHA_1
+#define SPI_MAX31856_BIT_ORDER  SPI_MSB_FIRST
+#define SPI_MAX31856_BLOCK_SIZE 8
+
+void max31856_init(max31856_t *max)
+{
+   // init GPIO for CS
+   gpio_init(max->pin_cs);
+   gpio_set_dir(max->pin_cs, GPIO_OUT);
+   gpio_put(max->pin_cs, 1);
+
+   // init SPI
+   spi_init(SPI_MAX31856, SPI_MAX31856_BOUD);
+   spi_set_format(SPI_MAX31856, SPI_MAX31856_BLOCK_SIZE, SPI_MAX31856_SPO, SPI_MAX31856_SPH, SPI_MAX31856_BIT_ORDER);
+
+   max->initilzed = true;
+}
+
+void max31856_deinit(max31856_t *max)
+{
+   max->initilzed = false;
+   spi_deinit(SPI_MAX31856);
+   gpio_deinit(max->pin_cs);
+}
+
+int max31856_write8(max31856_t *max, uint8_t addr, uint8_t value)
+{
+   if (!(max->initilzed))
+   {
+      return -1;
+   }
+   const uint8_t buff[2] = {addr | 0x80, value};
+   gpio_put(max->pin_cs, 0);
+   spi_write_blocking(SPI_MAX31856, &buff[0], 2);
+   gpio_put(max->pin_cs, 1);
+
+   return 0;
+}
diff --git a/src/max31856.h b/src/max31856.h
new file mode 100644
index 0000000..08fda16
--- /dev/null
+++ b/src/max31856.h
@@ -0,0 +1,53 @@
+#ifndef MAX31856_H
+#define MAX31856_H
+
+#include <stdint.h>
+
+typedef struct max31856_s {
+  uint8_t pin_cs;
+  bool initilzed;
+  bool autoDeinit;
+} max31856_t;
+
+void max31856_init(max31856_t *max);
+void max31856_deinit(max31856_t *max);
+int max31856_write8(max31856_t *max, uint8_t addr, uint8_t value);
+
+#define MAX31856_REG_CR0    0x00
+#define MAX31856_REG_CR0_CMODE      0x80
+#define MAX31856_REG_CR0_1SHOT      0x40
+#define MAX31856_REG_CR0_OCFAULT    0x10
+#define MAX31856_REG_CR0_JC         0x08
+#define MAX31856_REG_CR0_FAULT      0x04
+#define MAX31856_REG_CR0_FAULTCLR   0x02
+#define MAX31856_REG_CR0_50HZ       0x01
+
+#define MAX31856_REG_CR1    0x01
+#define MAX31856_REG_CR1_AVGSEL_1   0x00
+#define MAX31856_REG_CR1_AVGSEL_2   0x10
+#define MAX31856_REG_CR1_AVGSEL_4   0x20
+#define MAX31856_REG_CR1_AVGSEL_8   0x30
+#define MAX31856_REG_CR1_AVGSEL_16  0x40
+#define MAX31856_REG_CR1_TC_TYPE_B  0x00
+#define MAX31856_REG_CR1_TC_TYPE_E  0x01
+#define MAX31856_REG_CR1_TC_TYPE_J  0x02
+#define MAX31856_REG_CR1_TC_TYPE_K  0x03
+#define MAX31856_REG_CR1_TC_TYPE_N  0x04
+#define MAX31856_REG_CR1_TC_TYPE_R  0x05
+#define MAX31856_REG_CR1_TC_TYPE_S  0x06
+#define MAX31856_REG_CR1_TC_TYPE_T  0x07
+#define MAX31856_REG_CR1_VM_GAIN8   0x08
+#define MAX31856_REG_CR1_VM_GAIN32  0x0C
+
+#define MAX31856_REG_MASK   0x02
+#define MAX31856_REG_CJHF   0x03
+#define MAX31856_REG_CJLF   0x04
+#define MAX31856_REG_LTHFTH 0x05
+#define MAX31856_REG_LTHFTL 0x06
+#define MAX31856_REG_LTLFTH 0x07
+#define MAX31856_REG_LTLFTL 0x08
+#define MAX31856_REG_CJTO   0x09
+#define MAX31856_REG_CJTH   0x0A
+#define MAX31856_REG_CJTL   0x0B
+
+#endif
\ No newline at end of file