diff -r b3c3d54d2c7c -r 2da50a3d4e9f lib/unigraphic/SSD1322.cpp
--- a/lib/unigraphic/SSD1322.cpp	Sun Nov 01 22:21:19 2020 +0100
+++ b/lib/unigraphic/SSD1322.cpp	Sat Nov 07 19:20:39 2020 +0100
@@ -357,13 +357,15 @@
 {
   unsigned int x, y;
   unsigned int i;
-  set_row_address(0);
-  set_column_address(0);
 
+  pixel_buffer_mutex.lock();
   memcpy((void*)_trBuffer,
 		 (const void*)_pixelBuffer,
 		 DISPLAY_BUFFER_ELEMENTS * sizeof(DISPLAY_BUFFER_TYPE));
+  pixel_buffer_mutex.unlock();
 
+  set_row_address(0);
+  set_column_address(0);
   wr_cmd8(SSD1322_CMD_WRITE_RAM);
 
 #ifdef DEVICE_SPI_ASYNCH