From 80fc9e8a686293cc8c2009755efc73fe44d34e66 Mon Sep 17 00:00:00 2001
From: Neil McKechnie <neilmck999@gmail.com>
Date: Wed, 25 Aug 2021 00:29:57 +0100
Subject: [PATCH] Make LCD Display I2C calls synchronous.

---
 LiquidCrystal_I2C.cpp | 6 +++---
 LiquidCrystal_I2C.h   | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/LiquidCrystal_I2C.cpp b/LiquidCrystal_I2C.cpp
index 865868a..d7953f7 100644
--- a/LiquidCrystal_I2C.cpp
+++ b/LiquidCrystal_I2C.cpp
@@ -200,7 +200,7 @@ void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) {
   outputBuffer[len++] = highnib;
   outputBuffer[len++] = lownib|En;
   outputBuffer[len++] = lownib;
-  I2CManager.write(_Addr, outputBuffer, len);
+  I2CManager.write(_Addr, outputBuffer, len);  // Write command synchronously
 }
 
 // write 4 data bits to the HD44780 LCD controller.
@@ -214,7 +214,7 @@ void LiquidCrystal_I2C::write4bits(uint8_t value) {
   uint8_t len = 0;
   outputBuffer[len++] = _data|En;
   outputBuffer[len++] = _data;
-  I2CManager.write(_Addr, outputBuffer, len);
+  I2CManager.write(_Addr, outputBuffer, len);  // Write command synchronously
 }
 
 // write a byte to the PCF8574 I2C interface.  We don't need to set
@@ -223,5 +223,5 @@ void LiquidCrystal_I2C::expanderWrite(uint8_t value) {
   // Wait for previous request to complete before writing to outputbuffer.
   requestBlock.wait();
   outputBuffer[0] = value | _backlightval;
-  I2CManager.write(_Addr, outputBuffer, 1);
+  I2CManager.write(_Addr, outputBuffer, 1);  // Write command synchronously
 }
\ No newline at end of file
diff --git a/LiquidCrystal_I2C.h b/LiquidCrystal_I2C.h
index 6d65541..6cd4384 100644
--- a/LiquidCrystal_I2C.h
+++ b/LiquidCrystal_I2C.h
@@ -90,7 +90,8 @@ private:
 
   I2CRB requestBlock;
   uint8_t outputBuffer[4];
-  bool isBusy() { return requestBlock.isBusy(); }
+  // I/O is synchronous, so if this is called we're not busy!
+  bool isBusy() { return false; } 
 };
 
 #endif