From a1d92e32985f9c77c7fa6f09bd171391c8f5824d Mon Sep 17 00:00:00 2001
From: Mike O'Connor <moconnore@gmail.com>
Date: Tue, 19 Apr 2016 12:06:45 -0400
Subject: [PATCH] enable retain on publish. Fixes #20

---
 Adafruit_MQTT.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Adafruit_MQTT.cpp b/Adafruit_MQTT.cpp
index c4ff4e2..0f1d49c 100644
--- a/Adafruit_MQTT.cpp
+++ b/Adafruit_MQTT.cpp
@@ -583,8 +583,9 @@ uint8_t Adafruit_MQTT::publishPacket(uint8_t *packet, const char *topic,
                                      uint8_t *data, uint8_t bLen, uint8_t qos) {
   uint8_t *p = packet;
   uint16_t len;
+  uint8_t retain = 0x1;
 
-  p[0] = MQTT_CTRL_PUBLISH << 4 | qos << 1;
+  p[0] = MQTT_CTRL_PUBLISH << 4 | qos << 1 | retain << 0;
   // fill in packet[1] last
   p+=2;