diff --git a/csrc/u8x8_d_s1d15721.c b/csrc/u8x8_d_s1d15721.c
index 4ba87521..c75f604a 100644
--- a/csrc/u8x8_d_s1d15721.c
+++ b/csrc/u8x8_d_s1d15721.c
@@ -87,6 +87,10 @@ uint8_t u8x8_d_s1d15721_common(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void
       u8x8_cad_SendCmd(u8x8, 0x13);	/* col */
       u8x8_cad_SendArg(u8x8, x);
 
+      /* 4 Mar 2022: added the missing page address, issue 1802 */
+      u8x8_cad_SendCmd(u8x8, 0xb1);	/* page address */
+      u8x8_cad_SendArg(u8x8, y);
+
 	  u8x8_cad_SendCmd(u8x8, 0x1D );	//Data Write
 
       c = ((u8x8_tile_t *)arg_ptr)->cnt;
diff --git a/csrc/u8x8_d_ssd1320.c b/csrc/u8x8_d_ssd1320.c
index 0e99f618..0ab91a84 100644
--- a/csrc/u8x8_d_ssd1320.c
+++ b/csrc/u8x8_d_ssd1320.c
@@ -336,6 +336,8 @@ static const u8x8_display_info_t u8x8_d_ssd1320_cs1_160x132_display_info =
 
 
 /* the following sequence will work, but requires contrast to be very high */
+/* added #ifdef to avoid compiler warning, issue 1802 */
+#ifdef NOT_USED
 static const uint8_t u8x8_d_ssd1320_cs1_160x132_init_seq[] = {
     
     U8X8_DLY(1),
@@ -372,6 +374,7 @@ static const uint8_t u8x8_d_ssd1320_cs1_160x132_init_seq[] = {
     U8X8_END_TRANSFER(),             	/* disable chip */
     U8X8_END()             			/* end of sequence */
 };
+#endif
 
 /*
 OLED_WR_Byte(0xae,OLED_CMD);//Display OFF
diff --git a/csrc/u8x8_d_st75160.c b/csrc/u8x8_d_st75160.c
index 241677f2..59731f4f 100644
--- a/csrc/u8x8_d_st75160.c
+++ b/csrc/u8x8_d_st75160.c
@@ -84,6 +84,8 @@ static const uint8_t u8x8_d_st75256_256x128_powersave1_seq[] = {
   U8X8_END()             			/* end of sequence */
 };
 
+/* marked as unused to avoid compiler warning, issue 1802 */
+#ifdef NOT_USED
 static const uint8_t u8x8_d_st75256_jlx256128_flip0_seq[] = {
   U8X8_START_TRANSFER(),             	/* enable chip, delay is part of the transfer start */
   U8X8_C( 0x030 ),				/* select 00 commands */
@@ -107,6 +109,7 @@ static const uint8_t u8x8_d_st75256_jlx256128_flip1_seq[] = {
   U8X8_END_TRANSFER(),             	/* disable chip */
   U8X8_END()             			/* end of sequence */
 };
+#endif
 
 static const uint8_t u8x8_d_st75256_jlx172104_flip0_seq[] = {
   U8X8_START_TRANSFER(),             	/* enable chip, delay is part of the transfer start */
@@ -132,6 +135,8 @@ static const uint8_t u8x8_d_st75256_jlx172104_flip1_seq[] = {
   U8X8_END()             			/* end of sequence */
 };
 
+/* marked as unused to avoid compiler warning, issue 1802 */
+#ifdef NOT_USED
 static const uint8_t u8x8_d_st75256_jlx256160_flip0_seq[] = {
   U8X8_START_TRANSFER(),             	/* enable chip, delay is part of the transfer start */
   U8X8_C( 0x030 ),				/* select 00 commands */
@@ -155,7 +160,7 @@ static const uint8_t u8x8_d_st75256_jlx256160_flip1_seq[] = {
   U8X8_END_TRANSFER(),             	/* disable chip */
   U8X8_END()             			/* end of sequence */
 };
-
+#endif
 
 
 /*=============================================*/
diff --git a/sys/bitmap/common/u8x8_d_bitmap.c b/sys/bitmap/common/u8x8_d_bitmap.c
index a6941500..5fad80d5 100644
--- a/sys/bitmap/common/u8x8_d_bitmap.c
+++ b/sys/bitmap/common/u8x8_d_bitmap.c
@@ -174,7 +174,7 @@ static u8x8_display_info_t u8x8_bitmap_info =
 
 /* allocate bitmap */
 /* will be called by u8x8_SetupBitmap or u8g2_SetupBitmap */
-static uint8_t u8x8_SetBitmapDeviceSize(u8x8_t *u8x8, uint16_t pixel_width, uint16_t pixel_height)
+static uint8_t u8x8_SetBitmapDeviceSize(U8X8_UNUSED u8x8_t *u8x8, uint16_t pixel_width, uint16_t pixel_height)
 {
   /* update the global bitmap object, allocate the bitmap */
   if ( u8x8_bitmap_SetSize(&u8x8_bitmap, pixel_width, pixel_height) == 0 )
@@ -189,17 +189,17 @@ static uint8_t u8x8_SetBitmapDeviceSize(u8x8_t *u8x8, uint16_t pixel_width, uint
 }
 
 /* draw tiles to the bitmap, called by the device procedure */
-static void u8x8_DrawBitmapTiles(u8x8_t *u8x8, uint16_t tx, uint16_t ty, uint8_t tile_cnt, uint8_t *tile_ptr)
+static void u8x8_DrawBitmapTiles(U8X8_UNUSED u8x8_t *u8x8, uint16_t tx, uint16_t ty, uint8_t tile_cnt, uint8_t *tile_ptr)
 {
   u8x8_bitmap_DrawTiles(&u8x8_bitmap, tx, ty, tile_cnt, tile_ptr);
 }
 
-uint8_t u8x8_GetBitmapPixel(u8x8_t *u8x8, uint16_t x, uint16_t y)
+uint8_t u8x8_GetBitmapPixel(U8X8_UNUSED u8x8_t *u8x8, uint16_t x, uint16_t y)
 {
   return u8x8_bitmap_GetPixel(&u8x8_bitmap, x, y);
 }
 
-void u8x8_SaveBitmapTGA(u8x8_t *u8x8, const char *filename)
+void u8x8_SaveBitmapTGA(U8X8_UNUSED u8x8_t *u8x8, const char *filename)
 {
   u8x8_bitmap_SaveTGA(&u8x8_bitmap, filename);
 }
diff --git a/sys/sdl/common/u8x8_d_sdl_128x64.c b/sys/sdl/common/u8x8_d_sdl_128x64.c
index 4b07f7c7..a0ee3388 100644
--- a/sys/sdl/common/u8x8_d_sdl_128x64.c
+++ b/sys/sdl/common/u8x8_d_sdl_128x64.c
@@ -207,7 +207,7 @@ static const u8x8_display_info_t u8x8_sdl_240x160_info =
 };
 
 
-static uint8_t u8x8_d_sdl_gpio(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+static uint8_t u8x8_d_sdl_gpio(u8x8_t *u8x8, uint8_t msg, U8X8_UNUSED uint8_t arg_int, U8X8_UNUSED void *arg_ptr)
 {
 	static int debounce_cnt = 0;
 	static int curr_msg = 0;
diff --git a/sys/sdl/mui_all/Makefile b/sys/sdl/mui_all/Makefile
index 5030fe50..d24459b6 100644
--- a/sys/sdl/mui_all/Makefile
+++ b/sys/sdl/mui_all/Makefile
@@ -1,4 +1,4 @@
-CFLAGS = -g -Wall -I../../../csrc/.  `sdl2-config --cflags`
+CFLAGS = -g -Wall -Wextra -Wuninitialized -Wunused  -I../../../csrc/.  `sdl2-config --cflags`
 
 SRC = $(shell ls ../../../csrc/*.c) $(shell ls ../common/*.c ) $(shell ls ../../bitmap/common/*.c ) $(shell ls *.c )