From e11dc1e0598be21cdf83a6587a3d7bf41f96b056 Mon Sep 17 00:00:00 2001
From: Jens Dede <jd@comnets.uni-bremen.de>
Date: Thu, 15 Jul 2021 22:33:27 +0200
Subject: [PATCH] Fix for esp8266 ACK problem. Solution as suggested in #49 and
 #105

---
 RFM69.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/RFM69.cpp b/RFM69.cpp
index 418f7e1..67619eb 100644
--- a/RFM69.cpp
+++ b/RFM69.cpp
@@ -304,7 +304,12 @@ void RFM69::sendACK(const void* buffer, uint8_t bufferSize) {
   int16_t _RSSI = RSSI; // save payload received RSSI value
   writeReg(REG_PACKETCONFIG2, (readReg(REG_PACKETCONFIG2) & 0xFB) | RF_PACKET2_RXRESTART); // avoid RX deadlocks
   uint32_t now = millis();
-  while (!canSend() && millis() - now < RF69_CSMA_LIMIT_MS) receiveDone();
+  while (!canSend() && millis() - now < RF69_CSMA_LIMIT_MS){
+      receiveDone();
+#ifdef ESP8266
+      delay(1); // Give esp8266-based boards to handle background tasks
+#endif
+  }
   SENDERID = sender;    // TWS: Restore SenderID after it gets wiped out by receiveDone()
   sendFrame(sender, buffer, bufferSize, false, true);
   RSSI = _RSSI; // restore payload RSSI