Switch to a modernish C++ and cmake, add i2c stuff

CMakeLists.txt

@@ -2,7 +2,8 @@
 # https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
 # The following five lines of boilerplate have to be in your project's
 # CMakeLists in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.8)
+set(CMAKE_CXX_STANDARD 17)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 project(gay-ipod-fw)

main/CMakeLists.txt

@@ -1,2 +1,2 @@
-idf_component_register(SRCS "gay-ipod-fw.c"
+idf_component_register(SRCS "gay-ipod-fw.cpp"
                     INCLUDE_DIRS ".")

main/gay-ipod-fw.c

@@ -1,6 +0,0 @@
-#include <stdio.h>
-
-void app_main(void)
-{
-
-}

main/gay-ipod-fw.cpp

@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#include "esp_log.h"
+#include "driver/i2c.h"
+
+#define I2C_SDA_IO (0)
+#define I2C_SCL_IO (4)
+// TODO: check if fast mode i2c (400000) will work.
+#define I2C_CLOCK_HZ (100000)
+
+esp_err_t init_i2c(void) {
+  int i2c_port = 0;
+  i2c_config_t config = {
+    .mode = I2C_MODE_MASTER,
+    .sda_io_num = I2C_SDA_IO,
+    .scl_io_num = I2C_SCL_IO,
+    .sda_pullup_en = GPIO_PULLUP_ENABLE,
+    .scl_pullup_en = GPIO_PULLUP_ENABLE,
+    .master = {
+      .clk_speed = I2C_CLOCK_HZ,
+    },
+    .clk_flags = 0,
+  };
+  // TODO: INT line?
+
+  ESP_ERROR_CHECK(i2c_param_config(i2c_port, &config));
+  return i2c_driver_install(i2c_port, config.mode, 0, 0, 0);
+}
+
+extern "C" void app_main(void)
+{
+  init_i2c();
+}