Most HD44780 based and similar LCDs have two areas for the fonts, the GCROM and the GCRAM. the GCROM is not editable as this is written by manufacturer, while the GCRAM allows for user defined characters. This area allows the user to define 8 characters, and are usually used for custom symbols.
There are several tutorials online, just search for "HD44780 ...
Yup, it will definitely work. You could even throw together two quick (preferably Schottky) diodes and say... Two 100nF ceramic caps, (like the setup I made as a proof of concept for this answer) instead of an IC charge pump. Anyway, before I get too out of scope...
An LCD's Bias Voltage affects the contrast of the backlight (background) to characters (...
The PCF8574 has no concept of registers, as it has a single data register.
The standard protocol of reading a register means first the register address is transmitted, and then the data is read back.
Therefore, when the I2C library is commanded to do a register read, the PCF8574 understands the transmitted register address as data write. Also, when the I2C ...
If the 328p is signalling at 3.3V logic levels and the LCD wants 5V logic levels it should still work OK, unless it specifically says it won't that is. If you look at the normal thresholds for for 5V TTL logic compared with 3.3V TTL logic. Essentially the LCD will just receive good but weak 1's from the 328p and good strong 0's.
TTL thresholds, where Vdd = ...
There is two methods you can use:
Address individual pins. In XC8 you have such variables as LATBbits.LATB3 which you can set to 1 or 0 to turn an individual pin on or off.
Use bitwise operators and masks. You can "or" and "and" bits together to turn chunks of a port on or off, such as LATB &= 0xF0 will turn off the lower 4 bits. LATB |= 0x03 will ...
This problem occurs in 4 bit mode, the LCD screen misses a data nibble (a character is made of two 4bits nibbles) and then all subsequent characters are offset by 4bit.
You can check that this is your problem by checking that the garbage displayed is always repeated for a known string that is supposed to be shown, for example "Stop" will always show "7Fπ..."....
Looks like a bad LCD. You can try resoldering your connections to the LCD, they look poorly done. The joints should look like this:
See this guide for troubleshooting bad solder joints:
It can be done for some displays. Wide temperature range displays require a negative contrast voltage.
For the narrow temperature range displays, 0V represents maximum contrast, and it may be a bit high even at normal room temperature, but generally if you can adjust the viewing angle, a satisfactory angle can be found.
Personally, I prefer either a ...
Yes, it works and quite common. It's 0V to VCC, inclusive. Ground is 0V. So that works. You can also use a pair of resistors to make a voltage divider for a fixed contrast outside of just Ground. Only draw back is that you can't adjust the contrast, but unless you are taking the display to very different lighting environments all the time, who cares.
With any luck, your compiler already has the itoa() or sprintf() function.
If not, you have to implement it yourself.
The important thing is that this must be done from the right to the left:
const char *number_to_string(unsigned int number)
#define BUFFER_SIZE 12
static char buffer[BUFFER_SIZE]; /* must be static to be able to return it */
I do not have programming experience for TI uCs. I mostly use PICs. In the programs where I need to output numbers on the LCD screen I print char by char on the LCD.
Let's assume that I need to print out the number 123.
First I make a function which divides the number in individual numbers.
Then I display each number on LCD. You can improve the code by your ...
There is no inherent wear-out mechanism except in the backlight LED. The types with zebra connectors are more sensitive to moisture and if there are PCB contamination problems then the part may not tolerate humidity well.
Minimize those problems by keeping them cool, dry, away from vibration and shock, and keep the backlight current well below maximum.
My experience is that the 1602 type LCD display module will last a long time. What will not last a long time is the backlight if your module has one. In particular the ones I've used that have a white LED backlight last about 3 years before the LED brightness dims to the level as to render the display to about 10% of its original light level.
It is ...
In my experience, these displays need at least 4-5V between the VCC pin and the contrast pin, sometimes more. Which means you need to either power them with 5V and adjust the contrast pin to 0..1V, or you can power them with 3.3V, but you'll need negative voltage on the contrast pin. The latter is preferred if your MCU is not 5V-tolerant. Perhaps your ...
Character generator ROM is mask programmed, so the font ROM is not written, the ROM content is just set during chip manufacturing process. They cannot be reprogrammed by user. You can order e.g. HD44780 and other controller chips with custom characters from chip manufacturer.
It would appear that you have "issues" in your code.
The comments refer to PORTD but your code used PORTB.
Timing with the older HD44780 modules can be tricky.
You may find this complete and tested implementation useful:
; Filename: main.asm
; Author: dan1138
; Target: PIC18F452
; Assembler: MPASMWIN v5.22
; Assembler ...
You write "1001001000" into the DDRAM. The controller then searches the CGROM for that value and displays the character it finds at that value.
Because you are currently writing into the DDRAM, and have not sent the command to switch into the CGRAM. It requires an additional command to switch between them.
When you send the CGRAM data, then send the DDRAM ...
I'm trying to display the letter "A" on LM016L. I keep switching the E input but I get nothing.
Your current plan will not work.
Although your linked LCD module datasheet appears to be an abbreviated version, it says this LCD module uses the HD44780 controller. That is what you need to research.
For example, although not all LCD modules which claim to use ...
Like Manjenko said you can use a mask, and this is probably the best option especially in the case of the PIC18 devices since they have a LAT register that will avoid any read-modify-write issue.
If you just want to update the 4 least significant bits with the value of the data variable you can do something like this:
LATB = LATB & 0xF0 | (data & ...
Are there other (not HD44780-compatible) displays that would give this display when only power is supplied (but no controls), or is this specific for HD44780?
This is not specific for the HD44780 or similar controllers, but as a matter of fact most character lcds are HD44780 compatible. You can take it for granted.
The pinout I have used up to now for ...
Since you've already got power/ground/contrast mostly sorted out and - from your top photo - pins 15 and 16 are obviously power to the backlight, the heavy hitting's done and all that's left is data and control.
Since the controller is COB, I don't know of any way to visually tell the difference between data and control lines, but since the ,worst that ...
I'm almost certain that I saw a character LCD just like that in the past. That made me think that this might be a more a less standard module. Google's image search had discovered several.
If it looks like an HD44780 and it smells like an HD44780 then in all probability it is an HD44780. Yes, there are other display chips, but they are few and far between. Most people just stick to what is cheap and easy to use, which means HD44780.
On some models you need to send the initial setup commands multiple times. Also some models that I have consume power in an aggressive, pulsed way, so have a large capacitor close to the power supply (+ -) of the LCD to avoid power rail noise.
The HD44780 protocol only requires a maximum of 14 pins, usually found either along the long edge in a single row or on one of the short edges in a double row. There may be 16 instead, in which case the extra 2 are for the LED backlight. No other connections to the module should be required.
Why too thick?
Probably because the displays that came out were that thick, became widely used, then became the defacto standard. e.g. why make another size if it can't be used for a replacement.
How about this:
Slightly outside your range - 50mm x ...
A typical character LCD controller is designed to control an LCD up to 40 characters wide and two rows high (a matrix of 200x16 dots). Wiring such a controller directly to LCD glass, however, would require that it have 216 pins connected to the glass in addition to the pins needed for power, processor connection, etc. Having that many pins on a single IC ...
I found a workaround for the problem:
I added a 1000milisecond delay at startup, before initializing/configuring the LCD controller.
It worked pretty good for me.
A lower delay(100, 200ms) not worked so well.
Just a note: It happened only in 4bits databuss.