From 0594ff5f4d24a050df3945b3bbe3ddba5df4f4ef Mon Sep 17 00:00:00 2001
From: Stefan de Bruijn <stefan@nubilosoft.com>
Date: Tue, 3 Nov 2020 13:35:56 +0100
Subject: [PATCH] Finished implementing PWM and UART pin users

---
 Grbl_Esp32/src/PinUsers/PwmPin.cpp | 84 ++++++++++++++++++++++++++++++
 Grbl_Esp32/src/PinUsers/PwmPin.h   | 36 +++++++++++++
 Grbl_Esp32/src/PinUsers/Uart.cpp   |  1 +
 Grbl_Esp32/src/PinUsers/Uart.h     |  3 +-
 4 files changed, 123 insertions(+), 1 deletion(-)
 create mode 100644 Grbl_Esp32/src/PinUsers/PwmPin.cpp
 create mode 100644 Grbl_Esp32/src/PinUsers/PwmPin.h

diff --git a/Grbl_Esp32/src/PinUsers/PwmPin.cpp b/Grbl_Esp32/src/PinUsers/PwmPin.cpp
new file mode 100644
index 00000000..1e90666b
--- /dev/null
+++ b/Grbl_Esp32/src/PinUsers/PwmPin.cpp
@@ -0,0 +1,84 @@
+#include "PwmPin.h"
+
+#include "../Pin.h"
+#include "../Assert.h"
+#include "LimitedResource.h"
+
+#include <Arduino.h>
+
+namespace PinUsers {
+    class NativePwm : public PwmDetail {
+        static LimitedResource<16>& PwmChannelResources() {
+            // The ESP32 chip has 16 PWM channels.
+
+            static LimitedResource<16> instances_;
+            return instances_;
+        }
+
+        Pin      pin_;
+        int      pwmChannel_;
+        uint32_t frequency_;
+        uint32_t maxDuty_;
+        uint8_t  resolutionBits_;
+
+        /*
+            Calculate the highest precision of a PWM based on the frequency in bits
+
+            80,000,000 / freq = period
+            determine the highest precision where (1 << precision) < period
+        */
+        uint8_t calculatePwmPrecision(uint32_t freq) {
+            uint8_t precision = 0;
+
+            // increase the precision (bits) until it exceeds allow by frequency the max or is 16
+            // TODO is there a named value for the 80MHz?
+            while ((1 << precision) < (uint32_t)(80000000 / freq) && precision <= 16) {
+                precision++;
+            }
+
+            return precision - 1;
+        }
+
+    public:
+        NativePwm(Pin pin, uint32_t frequency, uint32_t maxDuty) : frequency_(frequency), maxDuty_(maxDuty) {
+            auto native = pin.getNative(Pin::Capabilities::PWM | Pin::Capabilities::Native);
+
+            pwmChannel_ = PwmChannelResources().tryClaim();
+            Assert(pwmChannel_ != -1, "PWM Channel could not be claimed. Are all PWM channels in use?");
+
+            resolutionBits_ = calculatePwmPrecision(frequency);
+
+            ledcSetup(pwmChannel_, frequency, resolutionBits_);
+            ledcAttachPin(native, pwmChannel_);
+            ledcWrite(pwmChannel_, 0);
+
+            // grbl_msg_sendf(CLIENT_SERIAL, MsgLevel::Info, "PWM Output:%d on Pin:%s Freq:%0.0fHz", _number, _pin.name().c_str(), _pwm_frequency);
+        }
+
+        uint32_t getFrequency() const override { return frequency_; }
+        uint32_t getMaxDuty() const override { return maxDuty_; }
+
+        void setValue(float value) {
+            if (value < 0) {
+                value = 0;
+            } else if (value > 1) {
+                value = 1;
+            }
+
+            auto duty = value * (uint32_t(1) << int(resolutionBits_));
+            ledcWrite(pwmChannel_, uint32_t(duty));
+        }
+
+        ~NativePwm() override {
+            ledcWrite(pwmChannel_, 0);
+            PwmChannelResources().release(pwmChannel_);
+        }
+    };
+
+    PwmPin::PwmPin(Pin pin, uint32_t frequency, uint32_t maxDuty) {
+        Assert(pin.capabilities().has(Pin::Capabilities::PWM | Pin::Capabilities::Native), "Pin does not support PWM");
+
+        // For now, we only support Native pins. In the future, we might support other pins.
+        _detail = new NativePwm(pin, frequency, maxDuty);
+    }
+}
diff --git a/Grbl_Esp32/src/PinUsers/PwmPin.h b/Grbl_Esp32/src/PinUsers/PwmPin.h
new file mode 100644
index 00000000..9b2b2427
--- /dev/null
+++ b/Grbl_Esp32/src/PinUsers/PwmPin.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include "../Pin.h"
+#include "../Assert.h"
+
+namespace PinUsers {
+    class PwmDetail {
+    public:
+        virtual uint32_t getFrequency() const = 0;
+        virtual uint32_t getMaxDuty() const   = 0;
+
+        // Sets the PWM value from 0..1.
+        virtual void setValue(float value) = 0;
+
+        virtual ~PwmDetail() {}
+    };
+
+    class PwmPin {
+        Pin        _pin;
+        PwmDetail* _detail;
+
+    public:
+        PwmPin() : _pin(Pin::UNDEFINED), _detail(nullptr) {}
+        PwmPin(Pin pin, uint32_t frequency, uint32_t maxDuty);
+
+        // Returns actual frequency which might not be exactly the same as requested(nearest supported value)
+        inline uint32_t getFrequency() const { return _detail->getFrequency(); }
+
+        // Returns actual maxDuty which might not be exactly the same as requested(nearest supported value)
+        inline uint32_t getMaxDuty() const { return _detail->getMaxDuty(); }
+
+        inline void setValue(float value) const { return _detail->setValue(value); }
+
+        inline ~PwmPin() { delete _detail; }
+    };
+}
diff --git a/Grbl_Esp32/src/PinUsers/Uart.cpp b/Grbl_Esp32/src/PinUsers/Uart.cpp
index 07e3b3c8..6e821c06 100644
--- a/Grbl_Esp32/src/PinUsers/Uart.cpp
+++ b/Grbl_Esp32/src/PinUsers/Uart.cpp
@@ -4,6 +4,7 @@
 #include "../Pins/PinOptionsParser.h"
 #include "../Assert.h"
 #include "LimitedResource.h"
+
 #include <driver/uart.h>
 
 namespace PinUsers {
diff --git a/Grbl_Esp32/src/PinUsers/Uart.h b/Grbl_Esp32/src/PinUsers/Uart.h
index 98170d28..c2e4df1c 100644
--- a/Grbl_Esp32/src/PinUsers/Uart.h
+++ b/Grbl_Esp32/src/PinUsers/Uart.h
@@ -1,9 +1,10 @@
 #pragma once
 
 #include "../Pin.h"
-#include <WString.h>
 #include "../Assert.h"
 
+#include <WString.h>
+
 // TODO FIXME: Uart also suffers from the way settings works: What you would want is 2 phases,
 // so (1) validation and preparation, and (2) building the actual uart. Now, it's all combined
 // in the single constructor, which works, but could throw an exception.