Some experience about 1602 LCD

I started reviewing LCD today! Oh my god! It feels like I'm learning it all over again. I've forgotten a lot of things. It seems that I need to practice very hard to be proficient in it. You won't remember what you learn in a short time with temporary efforts! Not to mention being proficient in application!

Let me talk about today's summary! Although it was a bit difficult at the beginning, it was not as difficult as before to follow the video step by step! Today, I found two examples to write the LCD program, and I looked at the PDF data of 1602. At the beginning, I looked at the program and wrote it by myself according to the timing diagram, but I couldn't get any results. I tried to modify it little by little according to the example, and finally found that it was a small delay problem, that is, there should be a small delay after inputting instructions or data to the data port. However, the timing diagram shows that the EN terminal level has dropped, and the data port is still assigning values, but in fact, there is a delay of about 5 milliseconds after the assignment. I don't understand the specific reason!

Regarding the problem of LCD character positioning, a routine I saw used coordinate positioning, which made me dizzy and I couldn't get it. In fact, in my opinion, the 1602 LCD can only display those few characters, and you won't make mistakes even if you count on your fingers! So it's better to control it directly! Pay special attention to the fact that as long as you want the character at that position to be displayed, you must assign a value to it, even if it is a space, it is considered a character, otherwise garbled characters will appear!

Let's talk about the driver that controls the LCD (let's call it a driver for now, anyway, it controls the LCD)! In fact, it's very simple to control this small LCD! Give it an initialization function (that is, tell it: little brother, you are going to start working), prepare it, and write the specific function according to the supporting PDF materials! Another one is the function of sending instructions. First, assign a value to RS, RS=0, when the MPU performs a write module operation, it points to the instruction register, and when the MPU performs a read module operation, it points to the address counter. RS=1, whether the MPU reads or writes, it points to the data register. Then assign a value to RW, assigning a value of 1 for a write operation and 0 for a read operation. Then there is the EN terminal. In fact, because the data will only read the command or data at the falling edge of EN, pull it high first, and then send the instruction to the data port. Now is the most critical, you must let it have a slight delay, for example, 5 milliseconds! Then set EN=0! Okay, this completes the instruction input! As for the data input function, the format is the same as the instruction input function, but the RS assignment is different! As for what command controls what function, just check the supporting information yourself! There is also a busy check problem, but... I don't know how to use it for the time being. I wrote the busy check into the program, but it went on strike! My current level is to write a small program to achieve a small function. I don't use the busy check for the time being, so I'll talk about it later!

Attached is the LCD driver function I wrote myself! Among them, dat is the LCD data import!

void del(uint i)
{
char j;
for(;i>0;i--)
for(j=125;j>0;j--);
}

void writecom(uchar com)
{
rs=0;
rw=0;
en=1;
dat=com;
del(5);
en=0;

}
void writedat(uchar da)
{
rs=1;
rw=0;
en= 1;
dat=da;
del(5);
en=0;
}

void init()
{ del(15);
writecom(0x38);
del(5)
; writecom(0x38)
; del(5);
writecom(0x38);
del(10);
writecom(0x08);
writecom(0x0e);
writecom(0x06);
writecom(0x0c);
writecom(0x80);

}