Support building fetch position packets

lib/PacketBuilder/include/PacketBuilder.h

@@ -12,7 +12,8 @@ public:
     void buildUpPacket(uint8_t *buffer, uint16_t shadeID);
     void buildDownPacket(uint8_t *buffer, uint16_t shadeID);
     void buildStopPacket(uint8_t *buffer, uint16_t shadeID);
-    void buildPositionPacket(uint8_t *buffer, uint16_t shadeID, float percentage);
+    void buildSetPositionPacket(uint8_t *buffer, uint16_t shadeID, float percentage);
+    void buildFetchPositionPacket(uint8_t *buffer, uint16_t shadeID);
 
 private:
     uint16_t address;

lib/PacketBuilder/src/PacketBuilder.cpp

@@ -66,7 +66,7 @@ void PacketBuilder::buildStopPacket(uint8_t *buffer, uint16_t shadeID)
     incrementRollingCodes();
 }
 
-void PacketBuilder::buildPositionPacket(uint8_t *buffer, uint16_t shadeID, float percentage)
+void PacketBuilder::buildSetPositionPacket(uint8_t *buffer, uint16_t shadeID, float percentage)
 {
     setPacketSize(buffer, 0x15);
     setConstants(buffer);
@@ -75,12 +75,12 @@ void PacketBuilder::buildPositionPacket(uint8_t *buffer, uint16_t shadeID, float
     setDestinationAddress(buffer, shadeID);
     setRollingCodes(buffer);
 
-    buffer[16] = 0x3F; // Command
+    buffer[16] = 0x3F; // Field command
-    buffer[17] = 0x5A; // Empty?
+    buffer[17] = 0x5A; // Constant
 
-    buffer[18] = 0x04; // Constant in this size packet?
+    buffer[18] = 0x04; // Field of 4 bytes
-    buffer[19] = 0x40; // Constant in this size packet?
+    buffer[19] = 0x40; // Field type (0x40 is set)
-    buffer[20] = 0x50; // Constant in this size packet?
+    buffer[20] = 0x50; // ID of position field
 
     uint16_t position = (uint16_t)(0xFFFF * percentage);
 
@@ -92,6 +92,26 @@ void PacketBuilder::buildPositionPacket(uint8_t *buffer, uint16_t shadeID, float
     incrementRollingCodes();
 }
 
+ void PacketBuilder::buildFetchPositionPacket(uint8_t *buffer, uint16_t shadeID) {
+    setPacketSize(buffer, 0x13);
+    setConstants(buffer);
+    setProtocolVersion(buffer, protocolVersion);
+    setSourceAddress(buffer, address);
+    setDestinationAddress(buffer, shadeID);
+    setRollingCodes(buffer);
+
+    buffer[16] = 0x3F; // Field command
+    buffer[17] = 0x5A; // Constant
+
+    buffer[18] = 0x02; // Field of 2 bytes
+    buffer[19] = 0x3F; // Field type (0x3F is fetch)
+    buffer[20] = 0x50; // ID of position field
+
+    calculateCRC(buffer);
+
+    incrementRollingCodes();
+ }
+
 void PacketBuilder::setPacketSize(uint8_t *buffer, uint8_t length) {
   buffer[1] = length;  // Packet size
 }

src/main.cpp

@@ -173,7 +173,7 @@ void onConnectionEstablished() {
   client.subscribe("hotdog/test_mqtt_blind/set_position", [] (const String &payload)  {
     uint16_t shadeID = 0x4EF1;
     float percentage = payload.toInt() / 100.0f;
-    hubPacketBuilder.buildPositionPacket(buffer, shadeID, percentage);
+    hubPacketBuilder.buildSetPositionPacket(buffer, shadeID, percentage);
     sendCommand(buffer);
   });