Noureddine Benabadji writes:
Embedded systems frequently use HD44780-type LCD displays as it is considered the most popular alphanumeric display controller. The interface comprises at least 14 pins: eight for data, three for control (EN, WR, RS), two for power supply (Vdd, Vss), and one for contrast (Vre). Configured in 8-bit mode, it requires at least 10 I/O lines (D0..D7, EN, RS). Configured in 4-bit mode, it requires at least six I/O lines (D4..D7, EN, RS). This last case seems usable when using an 8-pin PICmicro. However, 8-pin PICmicros have one pin as an input-only pin.
One wire brings power & data to LCD module - [Link]
EA DIP series displays from company Electronic Assembly provide an uncommon possibility to choose a graphic or a character display without a change of your device´s hardware.
A quality display with a high contrast and an automatic temperature compensation, easy mounting by soldering of pins into a PCB, a display maximally utilizing the module size – without overhangs and mounting openings, compatibility with industry standard graphic controllers (HD44780), low power consumption – all these are the features saying in favor of EA DIP series displays. To these benefits of EA DIP series, we can also add another uncommon feature – a possibility to change a character display for a graphic one without a change in hardware (at types of the same size). EA DIP series consists of several types as you can see in the following table.
Types with the same dimensions, for example the graphic EA DIP122J (122×32) and character EA DIP162J (2×16) and EA DIP203B (4×20) feature the same pinout, that´s why it is possible to use these types into the same PCB (at a modification of firmware of your device and meeting requirements of given types). It provides an elegant way how to create various versions of a product or to maintain a possibility of “upgrade” of your device from a character- to a graphic display.
Detailed description will provide you the EA DIP flyer, as well as datasheets at particular types. A novelty in our portfolio is the type EA DIP203B, which will replace the EA DIP204.
In case of interest in Electronic Assembly products, please contact us at email@example.com.
EA DIP displays – a free hand at a choice of a character or graphic display - [Link]
Embedded Lab has started a new tutorial series on Netduino programming and interfacing. This is the second tutorial in the series where interfacing between an HD44780 based character LCD and Netduino Plus is discussed.
Netduino and LCD interfacing tutorial – [Link]
Ian @ dangerousprototypes.com writes:
We came across Scott Harden’s brief article describing how to control an HD44780 LCD using an Attiny2313. After a number of unsuccessful attempts with other code he found this LCD library written by Martin Thomas for use with AVR-GCC. With a few mods to the code Scott produced the above results controlling his 2×20 LCD in 4-bit mode. The code provides for scrolling and wrapping and can even display Japanese characters. A handy tip for ATTiny2313 users.
ATTiny2313 controlling a HD44780 LCD via AVR-GCC - [Link]
Then I thought about it and I gave it a go. The result is positive! However, there is a gotcha; if you are using LCDs from different manufacturers or different types, the contrast setting might differ, as it did in my example. In order to overcome this, I would suggest putting two potentiometers in your board to adjust the contrasts individually. And don’t forget, you are using one more LCD, meaning more back light current. If you are using a 7805 without a heat-sink, you should re-calculate your thermal values.
Driving two character LCDs in parallel - [Link]
Chris @ PyroElectro.com writes:
There are quite a few articles that I’ve written that feature the 16×2 HD44780 LCD. However I never got the chance to make a simple example of how you can use an FPGA or CPLD with some verilog or VHDL to tell the LCD what to display.
This article will show the process of choosing parts, building a schematic, connecting the hardware and writing the hardware description to control a HD44780 LCD interface and output a few characters to the 16×2 LCD screen. To make things a little easier, we’ll use a familiar board, the CPLD Dev Board that I introduced a few years ago. It’s dated but still a good learning platform!
FPGA / CPLD 16×2 LCD Interface - [Link]
GPS for accurate synchronization and position measurement must use precise clock, so GPS satellites are equipped with atomic clocks. Clock accuracy is amazing ± 1 second in 1 million years. Using GPS module is available not only acquire position, speed, bet also time and date, so in this post I’ll explain how to do it.
Sirf II module has RS-232 interface for communication and it can be connected to PC Com port. Atmega in Arduino board has UART interface. RS-232 basically is the same UART, only zeros and ones voltage levels are different. To match levels MAX232 driver is used. Today’s GPS modules have UART port, so there isn’t any need for MAX232.
Arduino GPS clock using NMEA protocol - [Link]
Ishan Karve writes:
I generally tend to spend a lot of time working on my PC, not realising what the time it is. A bit of ponder made me realise that I did not have a clock in my room (Thats the Xcuse!!).. Clock in the deskbar/panel/Taskbar is so Uncool.. So I decided to make a custom made digital clock.
An immediate rummaging of my component inventory revealed that I had the necessary gear to accomplish the task..
Large Digit LCD Clock - [Link]
After our recent post about the commercial semi-conductor tester we started a discussion about building a similar open source project. What came up is this AVR based transistor tester (machine translation) by Markus.
It’s built around an ATmega8 IC that interfaces with a standard HD44780 16×2 character LCD. The circuit that does the testing is simplicity itself. Three pairs of resistors are connected to 6 pins of the microcontroller, and each pair is connected on the other end to one of the transistor pins.
The theory of operation is also relatively simple. The microcontroller cycles through different patterns on its output pins until a recognizable pattern is read on its input pins. It supports a very large range of devices:
- NPN and PNP bipolar junction transistors.
- P and N channel, enhanced and D type mosfet transistors.
- P and N channel JFET transistors.
- Common anode and common cathode dual diodes.
- Two diodes in connected in anti-parallel or series configuration.
- Single diode.
AVR-based transitor tester - [Link]
Giorgos Lazaridis writes:
Most of you probably know the popular HD44780 character LCD controller from Hitachi. Usually you find it on LCD display boards with 16 pins. One of these pins is called “Contrast Adjustment” and does exactly this: It adjusts the LCD contrast. This pin requires a voltage level. If a microcontrollers has a Digital to Analog module, then this pin can be directly interfaced with this module. But the D/A module is not very common, instead, the PWM module is.
In such applications, the backlit is usually done with LEDs, so a simple PWM driver can directly adjust the brightness. Unfortunately, the PWM module cannot be directly used to adjust the contrast. So, i made a very simple and small circuit to interface the PWM output of a microcontroller to the contrast adjustment pin of an HD44780 Character LCD.
PWM LCD Contrast Adjustment - [Link]