NAK I²C write when EDID protected

main.c

@@ -580,7 +580,11 @@ void i2c(void) __interrupt(IRQ_I2C) // auto wakeup
 			I2C_DR = *(uint8_t*)(EEPROM_ADDR + i2c_addr++); // transmit selected byte
 			i2c_input_new = false; // notify we send data
 		} else { // we will receive data
-			I2C_CR2 |= I2C_CR2_ACK; // ACK next received byte
+			if (EDID_PORT->IDR.reg & EDID_PIN) { // EDID switched off
+				I2C_CR2 &= I2C_CR2_ACK; // NACK next received byte to indicate programming it disabled
+			} else {
+				I2C_CR2 |= I2C_CR2_ACK; // ACK next received byte
+			}
 			i2c_input_new = true; // notify we get data
 		}
 	}