Although a few LEDs can provide a lot of information, a more advanced display is sometimes needed. Different libraries exist for use with assembler or C actually different versions for C exists, since there are different C-compilers that are not fully compatible. PCB dimensions are 80x36mm, and the viewable area of the display is 65x14mm. If you wish to have more than one LCD-module connected to one micro-controller, they can share all signals except this enable-line. Both are 2×16 chars with the Japanese character ROM.

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How do I pass an IO port as a parameter to a function?

Variable definitions Part 3: Data 6 PC 1: In this part we will connect the LCD module to an Atmega8 microcontrollerthen write some code to drive it.

How do I use a define’d constant in an asm statement? You can of course write your own. Shouldn’t I initialize all my variables? The Circuit Our first task is to build the circuit. The displays have single-row pin connections, which should be on the top to have the characters svr correctly on the display. Now the initialization sequence needs to be sent to the module. However, this means that any timing of the data sent must obey the restrictions worst-case from the LCD datasheet, and especially if the microcontroller uses an RC-oscillator for timing this can be a problem because the timing must be set even slower to work in all cases.


Only the lower 5 bits of each byte is used in the character generator, so the higher bits can be set in order to avoid problems with sending certain values such as 00 which would conflict with the 0-termination hx44780 strings in C.

I used a 5K pot, but a range of other values would work as well.

This hd4470 connected to the V0 or Vee -pin of the display and allows the contrast of the display to be adjusted. Go to the shop.


Although the pin connector suggests separate connections for the backlight, the displays I have are wired to supply the backlight from the main power-pins. So I asked him to put some aside, and I still have a bunch of them.

Only one of J1, J2 and J3 should be used. The repeated userdefined characters allows the user to avoid using certain characters such as 0 which is used in C to denote the end of a string. The really big displays have two HDcontrollers, and so have two enable-lines, controlling different parts of the display. Why does the compiler compile an 8-bit operation that uses bitwise operators into a bit operation in assembly?

So why do I have a bunch of these displays? I struggled with this for a long time as well. How do I trace an assembler file in avr-gdb? Why does my code not work? My UART is generating nonsense!

Next article 5 Ways to power an AVR 28 pin board. I use an updated AVRdude, so you may have to change the hd4780 to use a different programmer type, if you are using the standard distribution. In many microcontroller applications some sort of display is needed to present information and status of the controller to the user.


Peter Fleury Online: Interfacing a HD Based LCD to an AVR

Previous article New products for April. It is very simple, and is only made for 2×16 character displays although different sizes could be used with minor changes to the code. To make lcd16 work with newer versions of avr-libc, some changes are required, since the inpoutpsbi and cbi functions are now deprecated.

They have a 2×7 pin connector to the left side of the display when viewed from the front. This is used to switch the data-direction between the module and the mikrocontroller.

If one wants to be able to turn off the backlight, the displays have small solder jumpers or the current-limiting resistors can be removed. Why are many interrupt flags cleared by writing a logical 1? The modules have standard green wvr with black characters.