Support for rotation

Touch points can now be rotated.
Currently only 180 degrees.

Author: alex-code

GT911.cpp

@@ -98,7 +98,7 @@ bool GT911::readBytes(uint16_t reg, uint8_t *data, uint16_t size) {
     index++;
   }
 
-  return size == index;
+  return size == index - 1;
 }
 
 uint8_t GT911::calcChecksum(uint8_t *buf, uint8_t len) {
@@ -129,7 +129,18 @@ int8_t GT911::readTouches() {
 }
 
 bool GT911::readTouchPoints() {
-  return readBytes(GT911_REG_COORD_ADDR + 1, (uint8_t*)_points, sizeof(GTPoint) * GT911_MAX_CONTACTS);
+  bool result = readBytes(GT911_REG_COORD_ADDR + 1, (uint8_t*)_points, sizeof(GTPoint) * GT911_MAX_CONTACTS);
+
+  if (result && _rotation != Rotate::_0) {
+    for (uint8_t i = 0; i < GT911_MAX_CONTACTS; i++) {
+      if (_rotation == Rotate::_180) {
+        _points[i].x = _info.xResolution - _points[i].x;
+        _points[i].y = _info.yResolution - _points[i].y;
+      }
+    }
+  }
+
+  return result;
 }
 
 bool GT911::begin(int8_t intPin, int8_t rstPin, uint8_t addr, uint32_t clk) {
@@ -151,7 +162,11 @@ bool GT911::begin(int8_t intPin, int8_t rstPin, uint8_t addr, uint32_t clk) {
   _wire->setClock(clk);
   _wire->begin();
   _wire->beginTransmission(_addr);
-  return _wire->endTransmission() == 0;
+  if (_wire->endTransmission() == 0) {
+    readInfo(); // Need to get resolution to use rotation
+    return true;
+  }
+  return false;
 }
 
 bool GT911::productID(uint8_t *buf, uint8_t len) {
@@ -220,3 +235,7 @@ GTPoint GT911::getPoint(uint8_t num) {
 GTPoint *GT911::getPoints() {
   return _points;
 }
+
+void GT911::setRotation(Rotate rotation) {
+  _rotation = rotation;
+}

GT911.h

@@ -12,7 +12,7 @@
 
 #define GT911_MAX_CONTACTS 5
 
-#define GT911_REG_CFG  0x8047
+#define GT911_REG_CFG 0x8047
 #define GT911_REG_CHECKSUM 0x80FF
 #define GT911_REG_DATA 0x8140
 #define GT911_REG_ID 0x8140
@@ -24,6 +24,13 @@ enum : uint8_t {
 };
 
 class GT911 {
+  public:
+    enum class Rotate {
+      _0,
+      _90,
+      _180,
+      _270,
+    };
   private:
     TwoWire *_wire;
     uint8_t _intPin;
@@ -35,6 +42,8 @@ class GT911 {
     GTInfo _info;
     GTPoint _points[GT911_MAX_CONTACTS];
 
+    Rotate _rotation = Rotate::_0;
+
     void reset();
     void i2cStart(uint16_t reg);
     bool write(uint16_t reg, uint8_t data);
@@ -57,6 +66,8 @@ class GT911 {
     uint8_t touched(uint8_t mode = GT911_MODE_INTERRUPT);
     GTPoint getPoint(uint8_t num);
     GTPoint *getPoints();
+
+    void setRotation(Rotate rotation);
 };
 
 #endif

library.json

@@ -0,0 +1,4 @@
+{
+  "name": "GT911",
+  "version": "0.2.0"
+}