Character Lcd replace characters on lcd rom

Hi i had a Character lcd with I2C.(I don’t want buy graphic lcd or tft) but theres a problem when i use more than 7 characters its replaces old one. I don’t want this. But i learned lcd’s have a rom for loading existing characters.
Now i want replace factory loaded characters how i can do.
Note i was not going to replace english characters i just going to edit japan characters to custom symbols.

How i can do that.

T4h232: How I can do that.

Pay the manufacturer. :cold_sweat:

Paul__B: Pay the manufacturer. :cold_sweat:

So i needed buy custom lcd . Good idea but its bad. Or lets change this question to how to increase limit of custom characters.

I cannot modify rom of lcd beacuse someone or somemachine at factory put a glob into roms.:slight_smile: Its impossible to remove glob without damaging the chip under it

Go on. If you want to have more than 8 custom characters, you need a graphics controller.
Or buy a controller with in-built character set.

If you are committed to an existing HD44780-style LCD you will have to restrict each screen to rom-chars and 8-custom chars. Possible with imagination. After all there are only 32 chars visible in a 16x2 and I bet that several will be

More difficult for a 20x4 display but there are ST7920 displays with compatible pinout.

David.

david_prentice:
Go on. If you want to have more than 8 custom characters, you need a graphics controller.
Or buy a controller with in-built character set.

If you are committed to an existing HD44780-style LCD you will have to restrict each screen to rom-chars and 8-custom chars. Possible with imagination. After all there are only 32 chars visible in a 16x2 and I bet that several will be

More difficult for a 20x4 display but there are ST7920 displays with compatible pinout.

David.

But theres a another way must be available.
What happens i edit data on font chip with an assembly editor.
Or what happens i swap custom character chip and font chip.

What happens i edit data on font chip with an assembly editor. Or what happens i swap custom character chip and font chip.

You cannot edit font chip (CG ROM). There is NO write access to the CG ROM on the hd44780 based character LCDs. The characters cannot be changed.

I suggest that you get a display that fits your needs better.

groundFungus: You cannot edit font chip (CG ROM). There is NO write access to the CG ROM on the hd44780 based character LCDs. The characters cannot be changed.

I suggest that you get a display that fits your needs better.

Is theres another trick for displaying more than 7 characters (my lcd maximum supports 7 characters its weird i don't think it was hd based beacuse hd44780 had 8 character limit) . I know one trick that replace old custom character.

But i heard more thicks for example storing multiple bitmap in one byte and load into collumns and rows on display.

Is theres any trick exist or hacking exist for skipping this 7 character problem.

Post example screens.

You can use a different set of custom chars on each screen. You can NEVER display more than 8 custom chars on the same screen.

Yes, you can fiddle a bit. e.g. alternate custom chars faster than a human can see. (your human finds it uncomfortable)

It is much cheaper and easier to just buy a Graphics LCD.

David.

(my lcd maximum supports 7 characters

If the custom character lcd.write(0) will not show, try lcd.write(8). That will show the custom chacter 0.

So i needed buy a graphic lcd.

But i was thinking what about storing custom characters on eeprom.

Is this will work?

Also david says graphic lcd is cheaper than character lcd. But in my country (Turkey) its expensiver than character lcd. TFT's are weirdly cheaper than graphics lcd.

Most apps that use a 16x2 will only send a limited number of known text messages. If you are careful, you can avoid using more than 8 custom characters in any one screen.

You can store the custom characters in regular Flash memory. No need for an EEPROM.

If you need to show random messages you will inevitably run out of custom characters. In which case a 160x128 TFT or even a 128x64 GLCD can show more detail than a 20x4 CLCD.

David.

T4h232: Also david says graphic LCD is cheaper than character LCD.

No, he didn't say that at all and we know it is not the case. :roll_eyes:

He sad that getting a graphic LCD would be less trouble than mucking about to a ridiculous degree - which is in the long run, cheaper! :grinning:

You can store your custom characters where you like - on IBM punch cards if you like - but you will nevertheless only be ever able to display eight at any one time. :sunglasses: