From bf97fc13e463004c8efa58070d71a64f72c85190 Mon Sep 17 00:00:00 2001
From: Nico Weichbrodt <nico@weichbrodt.me>
Date: Sat, 10 Mar 2018 14:52:59 +0100
Subject: [PATCH] Made sending checksum in packets configurable, see #33

---
 esp-knx-ip-send.cpp | 9 +++++++--
 esp-knx-ip.h        | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/esp-knx-ip-send.cpp b/esp-knx-ip-send.cpp
index e02cc82..26301ee 100644
--- a/esp-knx-ip-send.cpp
+++ b/esp-knx-ip-send.cpp
@@ -14,8 +14,11 @@ void ESPKNXIP::send(address_t const &receiver, knx_command_type_t ct, uint8_t da
 {
 	if (receiver.value == 0)
 	return;
-
+#if SEND_CHECKSUM
 	uint32_t len = 6 + 2 + 8 + data_len + 1; // knx_pkt + cemi_msg + cemi_service + data + checksum
+#else
+	uint32_t len = 6 + 2 + 8 + data_len; // knx_pkt + cemi_msg + cemi_service + data
+#endif
 	DEBUG_PRINT(F("Creating packet with len "));
 	DEBUG_PRINTLN(len)
 	uint8_t buf[len];
@@ -49,6 +52,7 @@ void ESPKNXIP::send(address_t const &receiver, knx_command_type_t ct, uint8_t da
 	memcpy(cemi_data->data, data, data_len);
 	cemi_data->data[0] = (cemi_data->data[0] & 0x3F) | ((ct & 0x03) << 6);
 
+#if SEND_CHECKSUM
 	// Calculate checksum, which is just XOR of all bytes
 	uint8_t cs = buf[0] ^ buf[1];
 	for (uint32_t i = 2; i < len - 1; ++i)
@@ -56,7 +60,8 @@ void ESPKNXIP::send(address_t const &receiver, knx_command_type_t ct, uint8_t da
 		cs ^= buf[i];
 	}
 	buf[len - 1] = cs;
-
+#endif
+	
 	DEBUG_PRINT(F("Sending packet:"));
 	for (int i = 0; i < len; ++i)
 	{
diff --git a/esp-knx-ip.h b/esp-knx-ip.h
index 35ccc9f..f01323c 100644
--- a/esp-knx-ip.h
+++ b/esp-knx-ip.h
@@ -34,6 +34,7 @@
 // These values normally don't need adjustment
 #define MULTICAST_PORT            3671 // [Default 3671]
 #define MULTICAST_IP              IPAddress(224, 0, 23, 12) // [Default IPAddress(224, 0, 23, 12)]
+#define SEND_CHECKSUM             0
 
 // Uncomment to enable printing out debug messages.
 #define ESP_KNX_DEBUG