Touch: Add support for CST716

The touch driver now automatically detects whether
a CST816s (pinetime) or CST716 (some p8 watches) chip
is used, and adjusts the decoding logic accordingly.

For more information, see the discussion on
InfiniTimeOrg#492

src/displayapp/screens/SystemInfo.cpp

@@ -24,6 +24,16 @@ namespace {
         return "BMA425";
       case Pinetime::Controllers::MotionController::DeviceTypes::Unknown:
         return "???";
+  char CstUnknown[4] = {0};
+  const char* ToString(const Pinetime::Drivers::Cst816S::Variant variant, uint8_t chipId) {
+    switch (variant) {
+      case Pinetime::Drivers::Cst816S::Variant::Cst816S:
+        return "Cst816S";
+      case Pinetime::Drivers::Cst816S::Variant::Cst716:
+        return "Cst716";
+      case Pinetime::Drivers::Cst816S::Variant::Unknown:
+        snprintf(CstUnknown, 4, "?%x", chipId);
+        return CstUnknown;
     }
     return "???";
   }
@@ -146,7 +156,7 @@ std::unique_ptr<Screen> SystemInfo::CreateScreen2() {
                         "#444444 Backlight# %s\n"
                         "#444444 Last reset# %s\n"
                         "#444444 Accel.# %s\n"
-                        "#444444 Touch.# %x.%x.%x\n",
+                        "#444444 Tch.# %s-%x.%x\n",
                         dateTimeController.Day(),
                         static_cast<uint8_t>(dateTimeController.Month()),
                         dateTimeController.Year(),
@@ -162,7 +172,7 @@ std::unique_ptr<Screen> SystemInfo::CreateScreen2() {
                         brightnessController.ToString(),
                         resetReason,
                         ToString(motionController.DeviceType()),
-                        touchPanel.GetChipId(),
+                        ToString(touchPanel.GetVariant(), touchPanel.GetChipId()),
                         touchPanel.GetVendorId(),
                         touchPanel.GetFwVersion());
   lv_obj_align(label, lv_scr_act(), LV_ALIGN_CENTER, 0, 0);

src/drivers/Cst816s.cpp

@@ -32,18 +32,15 @@ bool Cst816S::Init() {
   twiMaster.Read(twiAddress, 0xa7, &dummy, 1);
   vTaskDelay(5);
 
-  // TODO This function check that the device IDs from the controller are equal to the ones
-  // we expect. However, it seems to return false positive (probably in case of communication issue).
-  // Also, it seems that some users have pinetimes that works correctly but that report different device IDs
-  // Until we know more about this, we'll just read the IDs but not take any action in case they are not 'valid'
-  CheckDeviceIds();
+  // Read the device ids, and use the chip ID to know which variant is used.
+  ReadDeviceIds();
 
   /*
   [2] EnConLR - Continuous operation can slide around
   [1] EnConUD - Slide up and down to enable continuous operation
   [0] EnDClick - Enable Double-click action
   */
-  static constexpr uint8_t motionMask = 0b00000101;
+  static constexpr uint8_t motionMask = 0b00000111;
   twiMaster.Write(twiAddress, 0xEC, &motionMask, 1);
 
   /*
@@ -52,6 +49,10 @@ bool Cst816S::Init() {
   [5] EnChange - Upon detecting a touch state changes, pulsed Low.
   [4] EnMotion - When the detected gesture is pulsed Low.
   [0] OnceWLP - Press gesture only issue a pulse signal is low.
+
+  This configures the chip in report mode (regular interrupts), instead of gesture mode.
+  Although the CST18S supports mode switching, the CST716 can only done one (permanently configured by the factory).
+  CST716 default is report mode.
   */
   static constexpr uint8_t irqCtl = 0b01110000;
   twiMaster.Write(twiAddress, 0xFA, &irqCtl, 1);
@@ -102,12 +103,29 @@ Cst816S::TouchInfos Cst816S::GetTouchInfo() {
 }
 
 void Cst816S::Sleep() {
+  // The Cst816S ignores this sleep command, as is has an auto-sleep function.
+  // During this auto-sleep, it can wake up by touch but has its I2C interface disabled.
+  // The Cst716 cannot wake up by touch, and can only come out of sleep by resetting it.
+  // The accelerometer can be used instead to generate wakeup events.
+
+  // Force a reset in case the chip went into auto-sleep mode
   nrf_gpio_pin_clear(PinMap::Cst816sReset);
   vTaskDelay(5);
   nrf_gpio_pin_set(PinMap::Cst816sReset);
   vTaskDelay(50);
+
+  // The CST816 and CST716 differ in their sleep register addresses
+  uint8_t sleepRegister = 0;
+  if(variant == Variant::Cst816S) {
+    sleepRegister = 0xE5;
+  } else if(variant == Variant::Cst716) {
+    sleepRegister = 0xA5;
+  }
   static constexpr uint8_t sleepValue = 0x03;
-  twiMaster.Write(twiAddress, 0xA5, &sleepValue, 1);
+  if(variant != Variant::Unknown) {
+    twiMaster.Write(twiAddress, sleepRegister, &sleepValue, 1);
+  }
+
   NRF_LOG_INFO("[TOUCHPANEL] Sleep");
 }
 
@@ -116,20 +134,22 @@ void Cst816S::Wakeup() {
   NRF_LOG_INFO("[TOUCHPANEL] Wakeup");
 }
 
-bool Cst816S::CheckDeviceIds() {
+void Cst816S::ReadDeviceIds() {
   // There's mixed information about which register contains which information
   if (twiMaster.Read(twiAddress, 0xA7, &chipId, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
     chipId = 0xFF;
-    return false;
   }
   if (twiMaster.Read(twiAddress, 0xA8, &vendorId, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
     vendorId = 0xFF;
-    return false;
   }
   if (twiMaster.Read(twiAddress, 0xA9, &fwVersion, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
     fwVersion = 0xFF;
-    return false;
   }
 
-  return chipId == 0xb4 && vendorId == 0 && fwVersion == 1;
+  variant = Variant::Unknown;
+  if(chipId == 0xB4) {
+    variant = Variant::Cst816S;
+  } else if(chipId == 0x20) {
+    variant = Variant::Cst716;
+  }
 }

src/drivers/Cst816s.h

@@ -6,6 +6,11 @@ namespace Pinetime {
   namespace Drivers {
     class Cst816S {
     public:
+      enum class Variant : uint8_t {
+        Unknown = 0,
+        Cst816S = 1,  // Used in Pinetime
+        Cst716  = 2   // Used in some P8(b) variants
+      };
       enum class Gestures : uint8_t {
         None = 0x00,
         SlideDown = 0x01,
@@ -44,8 +49,11 @@ namespace Pinetime {
       uint8_t GetFwVersion() const {
         return fwVersion;
       }
+      Variant GetVariant() const {
+        return variant;
+      }
     private:
-      bool CheckDeviceIds();
+      void ReadDeviceIds();
 
       // Unused/Unavailable commented out
       static constexpr uint8_t gestureIndex = 1;
@@ -69,6 +77,7 @@ namespace Pinetime {
       uint8_t chipId;
       uint8_t vendorId;
       uint8_t fwVersion;
+      Variant variant;
     };
 
   }

src/touchhandler/TouchHandler.cpp

@@ -25,25 +25,42 @@ bool TouchHandler::GetNewTouchInfo() {
     return false;
   }
 
-  if (info.gesture != Pinetime::Drivers::Cst816S::Gestures::None) {
-    if (gestureReleased) {
-      if (info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideDown ||
-          info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideLeft ||
-          info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideUp ||
-          info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideRight ||
-          info.gesture == Pinetime::Drivers::Cst816S::Gestures::LongPress) {
-        if (info.touching) {
+  // Cst716 (P8 variants) generates multiple "none" gesture events with info.touching == true during the physical gesture.
+  // The last event is a "slide" event with info.touching == true.
+  // gestureReleased state does not have to be computed manually, instead it occurs when event != "none".
+
+  // Cst816s (PineTime) generates multiple "slide" gesture events with info.touching == true during the physical gesture.
+  // The last of these "slide" events has info.touching == false.
+  // gestureReleased state is computed manually by checking for the transition to info.touching == false.
+
+  // In both cases, the event is bubbled up once the gesture is released.
+
+  if(touchPanel.GetVariant() == Pinetime::Drivers::Cst816S::Variant::Cst716) {
+    if (info.gesture != Pinetime::Drivers::Cst816S::Gestures::None) {
+      gesture = info.gesture;
+      info.touching = false;
+    }
+  } else if(touchPanel.GetVariant() == Pinetime::Drivers::Cst816S::Variant::Cst816S) {
+    if (info.gesture != Pinetime::Drivers::Cst816S::Gestures::None) {
+      if (gestureReleased) {
+        if (info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideDown ||
+            info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideLeft ||
+            info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideUp ||
+            info.gesture == Pinetime::Drivers::Cst816S::Gestures::SlideRight ||
+            info.gesture == Pinetime::Drivers::Cst816S::Gestures::LongPress) {
+          if (info.touching) {
+            gesture = info.gesture;
+            gestureReleased = false;
+          }
+        } else {
           gesture = info.gesture;
-          gestureReleased = false;
         }
-      } else {
-        gesture = info.gesture;
       }
     }
-  }
 
-  if (!info.touching) {
-    gestureReleased = true;
+    if (!info.touching) {
+      gestureReleased = true;
+    }
   }
 
   return true;