use more up to date C++

main/CMakeLists.txt

@@ -24,5 +24,5 @@ register_component()
 
 make_directory(${PB_OUT})
 
-component_compile_options("-Werror=incompatible-pointer-types")
+component_compile_options("-Werror=incompatible-pointer-types" "-std=c++14")
 component_compile_options(-I${PB_OUT})

main/ugv_io.cc

@@ -2,12 +2,9 @@
 
 #include <driver/gpio.h>
 #include <driver/mcpwm.h>
-#include <driver/uart.h>
 #include <esp_log.h>
-#include <math.h>
 
-#include "MPU.hpp"
+#include <math.h>
-#include "mpu/math.hpp"
 
 namespace ugv {
 namespace io {

main/ugv_io_mpu.cc

@@ -3,6 +3,10 @@
 #include <driver/uart.h>
 #include <esp_log.h>
 
+#include <math.h>
+
+constexpr float M_PI = atanf(1.f) * 4;
+
 #include "MPU.hpp"
 #include "i2c_mutex.h"
 #include "mpu/math.hpp"