initial commit. start platformio project

lib/README

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+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into executable file.
+
+The source code of each library should be placed in an own separate directory
+("lib/your_library_name/[here are source files]").
+
+For example, see a structure of the following two libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional, custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+and a contents of `src/main.c`:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+PlatformIO Library Dependency Finder will find automatically dependent
+libraries scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html

lib/nvm/src/NvmEeprom.cpp

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+/** \File NvmEeprom.cpp
+ * \copyright (c) 2025 len0rd
+ * \date   2025-01-09
+ */
+#include "NvmEeprom.hpp"
+#include <cstddef>
+#include "EEPROM.h"
+
+bool JoystickAxisCalibration::valid() const {
+    return min < mid < max;
+}
+
+void writeNvm(const NonVolatileMemory &nvm)
+{
+    for (size_t ii = 0; ii < sizeof(NonVolatileMemory); ii++)
+    {
+        EEPROM.write(ii, nvm.rawBytes[ii]);
+    }
+}
+
+void writeCalibration(const JoystickCalibration &cal) {
+    NonVolatileMemory nvm = {};
+    nvm.joystickCal = cal;
+    writeNvm(nvm);
+}
+
+void readNvm(NonVolatileMemory &nvm)
+{
+    for (size_t ii = 0; ii < sizeof(NonVolatileMemory); ii++)
+    {
+        nvm.rawBytes[ii] = EEPROM.read(ii);
+    }
+}

lib/nvm/src/NvmEeprom.hpp

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+/** \File NvmEeprom.hpp
+ * \copyright (c) 2025 len0rd
+ * \date   2025-01-09
+ *
+ * Very basic non-volatile memory handler to save and retrieve data
+ * needed by the controller
+ */
+#ifndef __NVMEEPROM_H__
+#define __NVMEEPROM_H__
+#include <cstdint>
+
+struct JoystickAxisCalibration
+{
+    /// Minimum value axis could be
+    uint16_t min;
+    /// average center point of axis
+    uint16_t mid;
+    /// max value axis could be
+    uint16_t max;
+
+    /// Check if the data in this struct makes sense
+    /// Returns true if data might be valid, otherwise false
+    bool valid() const;
+} __attribute__((packed));
+
+struct JoystickCalibration
+{
+    JoystickAxisCalibration x;
+    JoystickAxisCalibration y;
+} __attribute__((packed));
+
+union NonVolatileMemory
+{
+    JoystickCalibration joystickCal;
+    uint8_t rawBytes[sizeof(JoystickCalibration)] = {};
+};
+
+/// @brief Write the provided struct to EEPROM
+void writeNvm(const NonVolatileMemory &nvm);
+void writeCalibration(const JoystickCalibration&cal);
+
+void readNvm(NonVolatileMemory &nvm);
+
+#endif /* __NVMEEPROM_H__ */