2 files changed, 124 insertions, 0 deletions
diff --git a/src/drivers/Cst816s.cpp b/src/drivers/Cst816s.cpp
new file mode 100644
index 00000000..8ed65876
--- /dev/null
+++ b/src/drivers/Cst816s.cpp
@@ -0,0 +1,77 @@
+#include <FreeRTOS.h>
+#include <task.h>
+#include <nrfx_log.h>
+#include <legacy/nrf_drv_gpiote.h>
+
+#include "Cst816s.h"
+using namespace Pinetime::Drivers;
+
+/* References :
+ * This implementation is based on this article : https://medium.com/@ly.lee/building-a-rust-driver-for-pinetimes-touch-controller-cbc1a5d5d3e9
+ * Touch panel datasheet (weird chinese translation) : https://wiki.pine64.org/images/5/51/CST816S%E6%95%B0%E6%8D%AE%E6%89%8B%E5%86%8CV1.1.en.pdf
+ *
+ * TODO : we need a complete datasheet and protocol reference!
+ * */
+
+void Pinetime::Drivers::Cst816S::Init() {
+  nrf_gpio_cfg_output(pinReset);
+  nrf_gpio_pin_clear(pinReset);
+  vTaskDelay(20);
+  nrf_gpio_pin_set(pinReset);
+  vTaskDelay(200);
+
+  nrfx_twi_config_t config;
+  config.frequency = NRF_TWI_FREQ_400K;
+  config.scl = 7;
+  config.sda = 6;
+  config.interrupt_priority = NRFX_TWI_DEFAULT_CONFIG_IRQ_PRIORITY;
+  config.hold_bus_uninit = NRFX_TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT;
+
+  // Configure TWI in blocking mode (event_handler = nullptr)
+  auto ret = nrfx_twi_init(&twi, &config, nullptr, this);
+  nrfx_twi_enable(&twi);
+}
+
+
+void Cst816S::Probe() {
+  nrfx_err_t ret;
+  for(int i = 0; i < 127; i++) {
+    uint8_t data;
+    ret = nrfx_twi_rx(&twi, i, &data, 1);
+    if(ret == NRFX_SUCCESS) {
+      NRF_LOG_INFO("I2C device detected at address %d", i);
+    }
+  }
+}
+
+Cst816S::TouchInfos Cst816S::GetTouchInfo() {
+  Cst816S::TouchInfos info;
+
+  nrfx_twi_rx(&twi, address, touchData, 63);
+  auto nbTouchPoints = touchData[2] & 0x0f;
+
+  uint8_t i = 0;
+  uint8_t pointId = (touchData[touchIdIndex + (touchStep * i)]) >> 4;
+  if(nbTouchPoints == 0 && pointId == lastTouchId) return info;
+
+  // We fetch only the first touch point (the controller seems to handle only one anyway...)
+  info.isTouch = true;
+
+  auto xHigh = touchData[touchXHighIndex + (touchStep * i)] & 0x0f;
+  auto xLow = touchData[touchXLowIndex + (touchStep * i)];
+  uint16_t x = (xHigh << 8) | xLow;
+
+  auto yHigh = touchData[touchYHighIndex + (touchStep * i)] & 0x0f;
+  auto yLow = touchData[touchYLowIndex + (touchStep * i)];
+  uint16_t y = (yHigh << 8) | yLow;
+
+  auto action = touchData[touchEventIndex + (touchStep * i)] >> 6; /* 0 = Down, 1 = Up, 2 = contact*/
+  auto finger = touchData[touchIdIndex + (touchStep * i)] >> 4;
+  auto pressure = touchData[touchXYIndex + (touchStep * i)];
+  auto area = touchData[touchMiscIndex + (touchStep * i)] >> 4;
+
+  info.x = x;
+  info.y = y;
+  info.action = action;
+  return info;
+}
diff --git a/src/drivers/Cst816s.h b/src/drivers/Cst816s.h
new file mode 100644
index 00000000..fea33f40
--- /dev/null
+++ b/src/drivers/Cst816s.h
@@ -0,0 +1,47 @@
+#pragma once
+
+#include <nrfx_twi.h>
+
+namespace Pinetime {
+  namespace Drivers {
+    class Cst816S {
+      public :
+        struct TouchInfos {
+          uint16_t x;
+          uint16_t y;
+          uint8_t action;
+          uint8_t finger;
+          uint8_t pressure;
+          uint8_t area;
+          bool isTouch = false;
+        };
+
+        void Init();
+        void Probe();
+        TouchInfos GetTouchInfo();
+      private:
+        static constexpr uint8_t pinIrq = 28;
+        static constexpr uint8_t pinReset = 10;
+        static constexpr uint8_t address = 0x15;
+        static constexpr uint8_t lastTouchId = 0x0f;
+        static constexpr uint8_t touchPointNumIndex = 2;
+        static constexpr uint8_t touchMiscIndex = 8;
+        static constexpr uint8_t touchXYIndex = 7;
+        static constexpr uint8_t touchEventIndex = 3;
+        static constexpr uint8_t touchXHighIndex = 3;
+        static constexpr uint8_t touchXLowIndex = 4;
+        static constexpr uint8_t touchYHighIndex = 5;
+        static constexpr uint8_t touchYLowIndex = 6;
+        static constexpr uint8_t touchIdIndex = 5;
+        static constexpr uint8_t touchStep = 6;
+
+        uint8_t touchData[63];
+
+        // TODO TWI (i²C) should be created outside and injected into this class
+        // It will be needed when implementing other I²C devices
+        // (0x15 = touch, 0x18 = accelerometer, 0x44 = HR sensor)
+        nrfx_twi_t twi = NRFX_TWI_INSTANCE(1); // Use instance 1, because instance 0 is already used by SPI
+    };
+
+  }
+}