Using I2C Communication Protocol with LCD

It is hard to tell why "normal" mode does not work (you mean booting itself from flash, w/o debugger loading the code).

Do you any clock configuration without debugger? You code in main() just uses I2C config, nothing else. But booting from flash my need a lot more initialization code (e.g. clock config, flash latency, ...).

Also possible that you build with Linker Script a code image which is loaded and running from SRAM. The debugger will load fine and launch the code on SRAM. But in "normal" mode - there is no SRAM content.

Do you have any simple FW example, e.g. toggling an LED, which runs in "normal" mode? Check what all is done in main() and how your Linker Script will build and load the image. Extend such a "normal" project with your code.

My guess: you build FW to load and run only in SRAM (not properly booting from flash).

Let it "run normally" then when it isn't doing what you want, launch a debugger configuration without downloading new code or resetting the chip and find out where it is and why it's there.

Could also use a logic analyzer to watch the I2C lines.

Duplicate - merged.

Hello,    STM32F407G-DISC1   STMCubeIDE

I am trying to send data to LCD, but  TxE bit is never set and program stucks in while loop of lcd_send_cmd function.Also, SDA line seems always low as you can see in the below. What did I wrong? Any suggestion...

Thanks.

int main(void)
{
				GPIO_Handle_t I2C1_SCL_PB6 = { .PORTNAME = GPIOB,
												.PINCONF.PIN = GPIO_PIN_6,
												.PINCONF.MODE = GPIO_MODE_ALTARNATE,
												.PINCONF.OTYPE = GPIO_OTYPE_OD,
												.PINCONF.OSPEED = GPIO_OSPEED_HIGH,
												.PINCONF.PUPD = GPIO_PUPD_PU,
												.PINCONF.AF = AF4

				 	 	 	 	 	 };
				GPIO_Handle_t I2C1_SDA_PB7 = { .PORTNAME = GPIOB,
										 	 .PINCONF.PIN = GPIO_PIN_7,
												.PINCONF.MODE = GPIO_MODE_ALTARNATE,
												.PINCONF.OTYPE = GPIO_OTYPE_OD,
										 .PINCONF.OSPEED = GPIO_OSPEED_HIGH,
											 .PINCONF.PUPD = GPIO_PUPD_PU,
												.PINCONF.AF = AF4
								 	 };
				I2C1_CLOCK_ENABLE();
				gpioInit(&I2C1_SCL_PB6);
				gpioInit(&I2C1_SDA_PB7);
				//delayFunc();


				I2C1_FREQ_16MHZ();
				I2C1_FREQ_SCL_100MHZ();
				I2C1_RISE_TIME_17();

				I2C1_ENABLE();
				I2C1_ACK_ENABLE();
				I2C1_START_GENERATION();
				I2C1_SR1_READ();
				while(!I2C1_START_READ());
				I2C1->I2C_DR = SLAVE_ADDRESS_LCD;
				I2C1_SR1_READ();
				I2C1_SR2_READ();
			 lcd_init ();
 		 lcd_send_string ("ABCDE");



			while(1)
			{

			}

}
void lcd_init (void)
{
 // 4 bit initialisation


 delayFunc(); // wait for >40ms
 lcd_send_cmd (0x30);
 delayFunc(); // wait for >4.1ms
 lcd_send_cmd (0x30);
 delayFunc(); // wait for >100us
 lcd_send_cmd (0x30);
 delayFunc();
 lcd_send_cmd (0x20); // 4bit mode
 delayFunc();

 // display initialisation
 lcd_send_cmd (0x28); // Function set --> DL=0 (4 bit mode), N = 1 (2 line display) F = 0 (5x8 characters)
 delayFunc();
 lcd_send_cmd (0x08); //Display on/off control --> D=0,C=0, B=0 ---> display off
 delayFunc();
 lcd_send_cmd (0x01); // clear display
 delayFunc();
 lcd_send_cmd (0x06); //Entry mode set --> I/D = 1 (increment cursor) & S = 0 (no shift)
 delayFunc();
 lcd_send_cmd (0x0C); //Display on/off control --> D = 1, C and B = 0. (Cursor and blink, last two bits)
 delayFunc();
 
}
void lcd_send_cmd (char cmd) // lcd_send_data is identically the same 
{ // function with this one as well

 char data_u, data_l;
 data_u = (cmd&0xf0);
 data_l = ((cmd<<4)&0xf0);

 uint8_t data_t[4];
 data_t[0] = data_u|0x0C; //en=1, rs=0 -> bxxxx1100
 data_t[1] = data_u|0x08; //en=0, rs=0 -> bxxxx1000
 data_t[2] = data_l|0x0C; //en=1, rs=0 -> bxxxx1100
 data_t[3] = data_l|0x08; //en=0, rs=0 -> bxxxx1000

 for(int i = 0; i < 4; i++)
 {

 	 while (!I2C1_SR1_TXE_READ())
 		 ; // null statement
 		I2C1->I2C_DR = (data_t[i]);

 }
 	
}

Those SDA/SCL traces are not valid. Something is bad with your configuration. Do you have external pullups? I'd check GPIO settings in the registers to ensure OD AF mode is set. Perhaps do an analog capture, should see a fast falling edge and slow rising edge on both lines.

If it works with HAL, clearly a bug in your code, and you're the only one with insight into that. We can't see what you don't show us.

Perhaps compare I2C1 register settings with HAL to those with your own code. Should be able to spot differences quickly.