From b1559460eeb0f4d5feb9d247db499a07f7daa169 Mon Sep 17 00:00:00 2001
From: "Christian L. V. Madsen" <christian@oz1cm.dk>
Date: Sat, 14 Jun 2025 19:47:03 +0200
Subject: [PATCH] some progress on 4 bit mode.. but doesnt work

---
 lcd_hd44780.c | 37 +++++++++++++++++++++++++++++++++----
 lcd_hd44780.h |  2 ++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/lcd_hd44780.c b/lcd_hd44780.c
index a5290f2..63cca46 100644
--- a/lcd_hd44780.c
+++ b/lcd_hd44780.c
@@ -28,6 +28,32 @@ void lcd_hd44780_printf(lcd_hd44780_t *inst, char *string){
 	
 }*/
 
+static int WaitUntilReady(cm_lcd_hd44780_t *inst){
+
+	// If display is init, then use Polling Busy Flag!
+	if(inst->isInit){
+		// RS = 0, RW = 1
+		inst->gpio_data.rs_pin = 0;
+		inst->gpio_data.rw_pin = 1;
+
+		// Read from the data bus
+		inst->setGetGpio_event(&(inst->gpio_data), LCD_HD44780_GET);
+
+		// Loop until Busy Flag (D7) is clear
+		while (inst->gpio_data.data_bus & 0x80) {
+		    inst->setGetGpio_event(&(inst->gpio_data), LCD_HD44780_GET);
+		}
+
+		return 1;
+
+	}else{
+		inst->wait_event(1);
+		return 1;
+	}
+
+
+}
+
 static int lcd_write_8bit(cm_lcd_hd44780_t *inst, uint8_t dataOrCmd, hd44780_InstData_t mode){
 
 	// Set cmd on databus
@@ -41,13 +67,15 @@ static int lcd_write_8bit(cm_lcd_hd44780_t *inst, uint8_t dataOrCmd, hd44780_Ins
 
 	// E pin must be high when data is not ready yet.
 	inst->gpio_data.e_pin = 1;
-
 	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
 
 	// Then Clock data in with  E pin. Data is clocked on Falling edge:
 	inst->gpio_data.e_pin = 0;
 	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
 
+	// Wait until display is ready:
+	WaitUntilReady(inst);
+
 	// Then set E pin high so its ready for next time:
 	inst->gpio_data.e_pin = 1;
 	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
@@ -66,9 +94,9 @@ static void lcd_writeCmd_disp(cm_lcd_hd44780_t *inst, hd44780_cmd_t cmd, hd44780
 	}else{
 
 		// Write MSB first.
-		lcd_write_8bit(inst, (cmd >> 4) & 0xf, LCD_HD44780_INSTRUCTION);
+		lcd_write_8bit(inst, ((cmd >> 4) & 0x0F) << 4, LCD_HD44780_INSTRUCTION);
 		// Write LSB last.
-		lcd_write_8bit(inst, cmd & 0xf, LCD_HD44780_INSTRUCTION);
+		lcd_write_8bit(inst, (cmd & 0x0F) << 4, LCD_HD44780_INSTRUCTION);
 	}
 
 }
@@ -94,7 +122,8 @@ void lcd_hd44780_initDisp(cm_lcd_hd44780_t *inst){
 
 	lcd_writeCmd_disp(inst, LCD_HD44780_ENTRY_MODE,LCD_HD44780_SET);
 
-
+	// Init has been done, and we can now use Busy Flag polling instead of delay!
+	inst->isInit = 0x1;
 
 }
 
diff --git a/lcd_hd44780.h b/lcd_hd44780.h
index 02b83ae..f32f126 100644
--- a/lcd_hd44780.h
+++ b/lcd_hd44780.h
@@ -76,6 +76,8 @@ typedef struct{
 	wait_ms_Event_fpt wait_event;
 	lcd_hd44780_bitmode bit_mode;
 	hd44780_gpioset_t gpio_data;
+	// Flag for showing that init has been done.. After init im using polling Busy Flag instead of delay..
+	uint8_t isInit;
 	
 	
 }cm_lcd_hd44780_t;