From 094e61a7c189d2fde0d63cc02ca051c29692b438 Mon Sep 17 00:00:00 2001
From: BlackMark <me@blackmark.me>
Date: Mon, 30 Mar 2020 19:38:24 +0200
Subject: [PATCH] Add fan control according to temperature

---
 thermistor/main.cpp           | 26 +++++++++++++++++++++++++-
 thermistor/pwm.cpp            | 25 +++++++++++++++++++++++++
 thermistor/pwm.hpp            | 10 ++++++++++
 thermistor/thermistor.cppproj |  6 ++++++
 4 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 thermistor/pwm.cpp
 create mode 100644 thermistor/pwm.hpp

diff --git a/thermistor/main.cpp b/thermistor/main.cpp
index 0d9dcc4..f1cd990 100644
--- a/thermistor/main.cpp
+++ b/thermistor/main.cpp
@@ -12,11 +12,28 @@
 #define UART0_INT_VECTORS
 #include "uart/hardware0.hpp"
 
+#include "pwm.hpp"
 #include "thermistor.hpp"
 
+template <typename T>
+T clamp(double value, T lower, T upper)
+{
+	if (value < lower)
+		return lower;
+	if (value > upper)
+		return upper;
+	return static_cast<T>(value);
+}
+
+uint8_t temperatureCurve(double temperature)
+{
+	double fanSpeed = (10 * temperature - 200) / 3;
+	return clamp<uint8_t>(fanSpeed, 0, 100);
+}
+
 int main()
 {
-	uart::Uart0<> serial;
+	uart::Uart0<uart::Config<115200>> serial;
 	serial.init();
 
 	serial << F("Thermistor reader\r\n");
@@ -28,10 +45,14 @@ int main()
 
 	Thermistor temp;
 
+	pwm::init();
+	pwm::setDuty(100);
+
 	while (true) {
 		const auto adcSample = temp.sampleAdc(adcPin, 1000);
 		const auto thermistorResistance = temp.getResistance(adcSample);
 		const auto temperature = temp.getTemperature(thermistorResistance);
+		const auto fanSpeed = temperatureCurve(temperature);
 
 		char floatBuffer[16];
 
@@ -41,6 +62,9 @@ int main()
 		serial << F("Resistance: ") << floatBuffer << F("\r\n");
 		sprintf(floatBuffer, "%.2f", temperature);
 		serial << F("Temperature: ") << floatBuffer << F(" C \r\n");
+		serial << F("Fan speed: ") << fanSpeed << F("%\r\n");
+
+		pwm::setDuty(fanSpeed);
 
 		_delay_ms(1000);
 	}
diff --git a/thermistor/pwm.cpp b/thermistor/pwm.cpp
new file mode 100644
index 0000000..57d1233
--- /dev/null
+++ b/thermistor/pwm.cpp
@@ -0,0 +1,25 @@
+#include "pwm.hpp"
+
+#include "io/io.hpp"
+
+namespace pwm {
+
+static constexpr uint8_t PWM_TOP = 40;
+
+void init()
+{
+	io::Pin<io::P::D5> pwmPin;
+	pwmPin.dir(io::Dir::OUT);
+	pwmPin = false;
+
+	TCCR0A = (1 << COM0B1) | (1 << WGM00);
+	TCCR0B = (1 << WGM02) | (1 << CS01);
+	OCR0A = PWM_TOP;
+}
+
+void setDuty(uint8_t percent)
+{
+	OCR0B = (percent * PWM_TOP) / 100;
+}
+
+} // namespace pwm
diff --git a/thermistor/pwm.hpp b/thermistor/pwm.hpp
new file mode 100644
index 0000000..964ebb1
--- /dev/null
+++ b/thermistor/pwm.hpp
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace pwm {
+
+void init();
+void setDuty(uint8_t percent);
+
+} // namespace pwm
diff --git a/thermistor/thermistor.cppproj b/thermistor/thermistor.cppproj
index ebaf5c9..bce292a 100644
--- a/thermistor/thermistor.cppproj
+++ b/thermistor/thermistor.cppproj
@@ -212,6 +212,12 @@
     <Compile Include="main.cpp">
       <SubType>compile</SubType>
     </Compile>
+    <Compile Include="pwm.cpp">
+      <SubType>compile</SubType>
+    </Compile>
+    <Compile Include="pwm.hpp">
+      <SubType>compile</SubType>
+    </Compile>
     <Compile Include="thermistor.cpp">
       <SubType>compile</SubType>
     </Compile>