Added driver for ltc6992 pwm chip

firmware/drivers/ltc6992/ltc6992.cpp

+#include <ltc6992.hpp>
+#include <stdint.h>
+
+bool Ltc6992::initialized_ = false;
+uint16_t Ltc6992::current_level_ = 0b0000000000000000;
+uint16_t Ltc6992::max_level_ = 0b0000111111111111;
+uint16_t Ltc6992::min_level_ = 0b0000000000000000;
+
+void Ltc6992::init(){
+    analogWriteResolution(12);
+    current_level_ = 0b0000000000000000;
+    analogWrite(LTC6992_PIN, current_level_);
+    initialized_ = true;
+}
+
+bool Ltc6992::set_level(double lev){
+    if(!initialized_){
+        return false;
+    }
+    if(lev > 1.0 || lev < 0.0){
+        //If input out of bounds, silently turn off
+        lev = 0.0;
+    }
+    uint16_t new_level = static_cast<uint16_t>(static_cast<int>(static_cast<double>(static_cast<int>(max_level_)) * lev));
+    if(new_level > max_level_ || new_level < min_level_){
+        //If something strange happens, turn off
+        current_level_ = min_level_;
+    }
+    else{
+        current_level_ = new_level;
+    }
+    analogWrite(LTC6992_PIN, current_level_);
+    return current_level_ == new_level;
+}
+
+double Ltc6992::current_level(){
+    return static_cast<double>(current_level_) / static_cast<double>(max_level_);
+}
+
+unsigned Ltc6992::current_ulevel(){
+    return unsigned(current_level_);
+}
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firmware/drivers/ltc6992/ltc6992.hpp

+#ifndef LTC6992_HPP_INCLUDED
+#define LTC6992_HPP_INCLUDED
+#include <stdint.h>
+#include <Arduino.h>
+
+#define LTC6992_PIN DAC1
+
+struct Ltc6992{
+    //first call to a member must be to init()
+    static void init();
+    //lev is in [0, 1]
+    static bool set_level(double lev);
+
+    static double current_level();
+
+    static unsigned current_ulevel();
+
+private:
+    static bool initialized_;
+    static uint16_t current_level_;
+    static uint16_t max_level_;
+    static uint16_t min_level_;
+};
+
+#endif
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