Add mozc dial version.

Co-authored-by: Takashi Toyoshima <toyoshim@google.com>
Co-authored-by: Shun Ikejima <ikejima@google.com>

mozc-dial/firmware/common/motor_controller.cc

@@ -0,0 +1,108 @@
+// Copyright 2025 Google Inc.
+// Use of this source code is governed by an Apache License that can be found
+// in the LICENSE file.
+
+#include "motor_controller.h"
+
+#include <cstdio>
+#include <initializer_list>
+
+#include "hardware/gpio.h"
+#include "pico/time.h"
+
+static constexpr int kMotorStepIntervalInUs = 2000;
+
+// Activate 1 of 8 motor drivers in a specific step phase.
+class MotorController::Decoder {
+ public:
+  Decoder(int8_t a0, int8_t a1, int8_t a2, int8_t en)
+      : a0_(a0), a1_(a1), a2_(a2), en_(en) {
+    for (int8_t gpio : {en, a0, a1, a2}) {
+      gpio_init(gpio);
+      gpio_set_dir(gpio, GPIO_OUT);
+      gpio_put(gpio, false);
+    }
+  }
+  Decoder(const Decoder&) = delete;
+  Decoder& operator=(const Decoder&) = delete;
+  ~Decoder() = default;
+
+  void Select(uint8_t index) {
+    hard_assert(index < 8);
+    gpio_put(a0_, index & 1);
+    gpio_put(a1_, index & 2);
+    gpio_put(a2_, index & 4);
+    gpio_put(en_, true);
+  }
+  void Unselect() { gpio_put(en_, false); }
+
+ private:
+  int8_t a0_;
+  int8_t a1_;
+  int8_t a2_;
+  int8_t en_;
+};
+
+// static
+bool MotorController::OnAlarm(repeating_timer* t) {
+  static_cast<MotorController*>(t->user_data)->Step();
+  return true;
+}
+
+MotorController::MotorController(Mode mode) {
+  if (mode == Mode::k9Motor) {
+    // Each decoder is responsible for a specific phase to driver 1 of 8 motor
+    // drivers. As we have 4 phases, it can drive 4 motors at the same time, and
+    // by time division multiplexing, we make them drive 8 motors.
+    decoder_[0] = std::make_unique<Decoder>(1, 2, 3, 4);
+    decoder_[1] = std::make_unique<Decoder>(5, 6, 7, 8);
+    decoder_[2] = std::make_unique<Decoder>(9, 10, 11, 12);
+    decoder_[3] = std::make_unique<Decoder>(13, 14, 15, 16);
+  }
+
+  // 9th motor driver is controlled via GPIOs directly.
+  for (int8_t gpio : {17, 18, 19, 20}) {
+    gpio_init(gpio);
+    gpio_set_dir(gpio, GPIO_OUT);
+    gpio_put(gpio, false);
+  }
+
+  add_repeating_timer_us(-kMotorStepIntervalInUs, OnAlarm, this, &timer_);
+}
+
+MotorController::~MotorController() {}
+
+void MotorController::Start(uint8_t index) {
+  hard_assert(index < kNumOfMotors);
+  started_[index] = true;
+}
+
+void MotorController::Stop(uint8_t index) {
+  hard_assert(index < kNumOfMotors);
+  started_[index] = false;
+}
+
+void MotorController::Step() {
+  // Drive first 4 motor drivers in even phases, and later 4 ones in odd
+  // phases.
+  size_t start_index = (phase_ & 1) ? kNumOfPhases : 0;
+  size_t half_phase = phase_ >> 1;
+  for (size_t i = start_index; i < start_index + kNumOfPhases; ++i) {
+    if (!decoder_[i]) {
+      continue;
+    }
+    if (started_[i]) {
+      decoder_[(i + half_phase) % kNumOfPhases]->Select(i);
+    } else {
+      decoder_[(i + half_phase) % kNumOfPhases]->Unselect();
+    }
+  }
+  // Drive the last 9th motor drivers.
+  bool on = started_[8] && phase_ & 1;
+  gpio_put(17, on && half_phase == 0);
+  gpio_put(18, on && half_phase == 1);
+  gpio_put(19, on && half_phase == 2);
+  gpio_put(20, on && half_phase == 3);
+
+  phase_ = (phase_ + 7) % 8;
+}