Update to high speed encoder stream

ESP32/.gitignore

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+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch

ESP32/include/README

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+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the convention is to give header files names that end with `.h'.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html

ESP32/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 the executable file.
+
+The source code of each library should be placed in a separate directory
+("lib/your_library_name/[Code]").
+
+For example, see the structure of the following example libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional. for 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
+
+Example contents of `src/main.c` using Foo and Bar:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+The PlatformIO Library Dependency Finder will find automatically dependent
+libraries by scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html

ESP32/platformio.ini

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+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:esp32dev]
+platform = espressif32
+board = esp32dev
+framework = arduino
+monitor_speed = 921600

ESP32/src/main.cpp

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+#include <Arduino.h>
+
+constexpr uint8_t TURN_PIN = 27;
+constexpr uint8_t PULSE_PIN = 26;
+constexpr uint8_t GP_PINS[] = {32, 33};
+
+constexpr uint32_t BAUD_RATE = 921600;
+constexpr size_t EVENT_BUFFER_SIZE = 256;
+constexpr size_t GP_INPUT_COUNT = sizeof(GP_PINS) / sizeof(GP_PINS[0]);
+constexpr size_t PACKET_PULSE_COUNT = 16;
+constexpr size_t INPUT_PULSES_PER_TURN = 1024;
+constexpr size_t PULSE_DECIMATION = 4;
+constexpr size_t OUTPUT_PULSES_PER_TURN = INPUT_PULSES_PER_TURN / PULSE_DECIMATION;
+constexpr uint32_t UINT16_DELTA_MAX = UINT16_MAX;
+
+static_assert(INPUT_PULSES_PER_TURN % PULSE_DECIMATION == 0);
+
+constexpr uint8_t TURN_MAGIC[] = {0xE7, 0x54, 0xC3, 0xA1};
+constexpr uint8_t PULSE16_MAGIC[] = {0xE7, 0x50, 0xC3, 0xA1};
+constexpr uint8_t PULSE32_MAGIC[] = {0xE7, 0x70, 0xC3, 0xA1};
+constexpr uint8_t GP_MAGIC[] = {0xE7, 0x47, 0xC3, 0xA1};
+
+volatile uint32_t PULSE_REG[EVENT_BUFFER_SIZE];
+volatile uint8_t PULSE_W_HEAD = 0;
+uint8_t PULSE_R_HEAD = 0;
+
+volatile uint32_t TURN_REG[EVENT_BUFFER_SIZE];
+volatile uint8_t TURN_W_HEAD = 0;
+uint8_t TURN_R_HEAD = 0;
+
+volatile uint32_t GP_REG[GP_INPUT_COUNT][EVENT_BUFFER_SIZE];
+volatile uint8_t GP_W_HEAD[GP_INPUT_COUNT] = {};
+uint8_t GP_R_HEAD[GP_INPUT_COUNT] = {};
+
+uint32_t packet_deltas[PACKET_PULSE_COUNT];
+size_t packet_count = 0;
+size_t raw_turn_pulse_count = 0;
+size_t output_turn_pulse_count = 0;
+uint32_t previous_timestamp = 0;
+bool have_active_turn = false;
+
+void ARDUINO_ISR_ATTR handle_pulse_isr() {
+  PULSE_REG[PULSE_W_HEAD] = micros();
+  PULSE_W_HEAD = PULSE_W_HEAD + 1;
+}
+
+void ARDUINO_ISR_ATTR handle_turn_isr() {
+  TURN_REG[TURN_W_HEAD] = micros();
+  TURN_W_HEAD = TURN_W_HEAD + 1;
+}
+
+void ARDUINO_ISR_ATTR handle_gp_falling(size_t input) {
+  GP_REG[input][GP_W_HEAD[input]] = micros();
+  GP_W_HEAD[input] = GP_W_HEAD[input] + 1;
+}
+
+void ARDUINO_ISR_ATTR handle_gp0_isr() {
+  handle_gp_falling(0);
+}
+
+void ARDUINO_ISR_ATTR handle_gp1_isr() {
+  handle_gp_falling(1);
+}
+
+bool timestamp_is_before(uint32_t lhs, uint32_t rhs) {
+  return static_cast<int32_t>(lhs - rhs) < 0;
+}
+
+void write_magic(const uint8_t magic[4]) {
+  Serial.write(magic, 4);
+}
+
+void write_u16(uint16_t value) {
+  Serial.write(reinterpret_cast<const uint8_t *>(&value), sizeof(value));
+}
+
+void write_u32(uint32_t value) {
+  Serial.write(reinterpret_cast<const uint8_t *>(&value), sizeof(value));
+}
+
+void send_packet(size_t used_count) {
+  bool needs_u32 = false;
+
+  for (size_t index = 0; index < PACKET_PULSE_COUNT; index++) {
+    if (index >= used_count) {
+      packet_deltas[index] = 0;
+    }
+
+    if (packet_deltas[index] > UINT16_DELTA_MAX) {
+      needs_u32 = true;
+    }
+  }
+
+  write_magic(needs_u32 ? PULSE32_MAGIC : PULSE16_MAGIC);
+
+  if (needs_u32) {
+    for (size_t index = 0; index < PACKET_PULSE_COUNT; index++) {
+      write_u32(packet_deltas[index]);
+    }
+  } else {
+    for (size_t index = 0; index < PACKET_PULSE_COUNT; index++) {
+      write_u16(static_cast<uint16_t>(packet_deltas[index]));
+    }
+  }
+}
+
+void flush_partial_packet() {
+  if (packet_count == 0) {
+    return;
+  }
+
+  send_packet(packet_count);
+  packet_count = 0;
+}
+
+void start_turn(uint32_t timestamp) {
+  if (have_active_turn) {
+    flush_partial_packet();
+  }
+
+  write_magic(TURN_MAGIC);
+  write_u32(timestamp);
+
+  have_active_turn = true;
+  previous_timestamp = timestamp;
+  packet_count = 0;
+  raw_turn_pulse_count = 0;
+  output_turn_pulse_count = 0;
+}
+
+void handle_pulse(uint32_t timestamp) {
+  if (!have_active_turn || raw_turn_pulse_count >= INPUT_PULSES_PER_TURN) {
+    return;
+  }
+
+  const bool should_emit = raw_turn_pulse_count % PULSE_DECIMATION == 0;
+  raw_turn_pulse_count++;
+
+  if (!should_emit || output_turn_pulse_count >= OUTPUT_PULSES_PER_TURN) {
+    return;
+  }
+
+  packet_deltas[packet_count] = timestamp - previous_timestamp;
+  previous_timestamp = timestamp;
+  packet_count++;
+  output_turn_pulse_count++;
+
+  if (packet_count == PACKET_PULSE_COUNT) {
+    send_packet(PACKET_PULSE_COUNT);
+    packet_count = 0;
+  }
+}
+
+void handle_gp(size_t channel, uint32_t timestamp) {
+  if (!have_active_turn) {
+    return;
+  }
+
+  write_magic(GP_MAGIC);
+  Serial.write(static_cast<uint8_t>(channel));
+  write_u32(timestamp);
+}
+
+void process_next_event() {
+  enum EventType { NONE, TURN, PULSE, GP };
+
+  EventType next_type = NONE;
+  uint32_t next_timestamp = 0;
+  size_t next_gp_channel = 0;
+
+  if (TURN_R_HEAD != TURN_W_HEAD) {
+    next_type = TURN;
+    next_timestamp = TURN_REG[TURN_R_HEAD];
+  }
+
+  if (PULSE_R_HEAD != PULSE_W_HEAD &&
+      (next_type == NONE ||
+       timestamp_is_before(PULSE_REG[PULSE_R_HEAD], next_timestamp))) {
+    next_type = PULSE;
+    next_timestamp = PULSE_REG[PULSE_R_HEAD];
+  }
+
+  for (size_t channel = 0; channel < GP_INPUT_COUNT; channel++) {
+    if (GP_R_HEAD[channel] == GP_W_HEAD[channel]) {
+      continue;
+    }
+
+    const uint32_t timestamp = GP_REG[channel][GP_R_HEAD[channel]];
+    if (next_type == NONE || timestamp_is_before(timestamp, next_timestamp)) {
+      next_type = GP;
+      next_timestamp = timestamp;
+      next_gp_channel = channel;
+    }
+  }
+
+  switch (next_type) {
+    case TURN:
+      start_turn(next_timestamp);
+      TURN_R_HEAD++;
+      break;
+    case PULSE:
+      handle_pulse(next_timestamp);
+      PULSE_R_HEAD++;
+      break;
+    case GP:
+      handle_gp(next_gp_channel, next_timestamp);
+      GP_R_HEAD[next_gp_channel]++;
+      break;
+    case NONE:
+      break;
+  }
+}
+
+void setup() {
+  Serial.begin(BAUD_RATE);
+  attachInterrupt(digitalPinToInterrupt(TURN_PIN), handle_turn_isr, RISING);
+  attachInterrupt(digitalPinToInterrupt(PULSE_PIN), handle_pulse_isr, FALLING);
+  attachInterrupt(digitalPinToInterrupt(GP_PINS[0]), handle_gp0_isr, FALLING);
+  attachInterrupt(digitalPinToInterrupt(GP_PINS[1]), handle_gp1_isr, FALLING);
+}
+
+void loop() {
+  process_next_event();
+}

ESP32/test/README

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+
+This directory is intended for PlatformIO Test Runner and project tests.
+
+Unit Testing is a software testing method by which individual units of
+source code, sets of one or more MCU program modules together with associated
+control data, usage procedures, and operating procedures, are tested to
+determine whether they are fit for use. Unit testing finds problems early
+in the development cycle.
+
+More information about PlatformIO Unit Testing:
+- https://docs.platformio.org/en/latest/advanced/unit-testing/index.html