I am looking to start a project using a monochrome LCD with touch capibiliies. I am wondering what sort of microcontroller I will need. Will be able to get away with using a PIC or will I need something with a little more power? Anyone have any idea what sort of program space I will need? There will be no animation and mostly graphic buttons and text.
I assume you are using a STN type LCD module with a touch screen interface. You'll need a 4-wire touch controller (assuming you are using a 4-wire system). it's possible to make your own, but existing parts to do this are common (Philips UCB14000 for instance).
LCD video controllers implement huge amounts of logic to control the pixel drawing. you might get away with a PIC if you were using dual ported RAM - otherwise you might well need something more beefy.
A lot depends on exactly what style (resolution, type etc) of LCD display you are using.
The versions I dealt with (mostly Optrex) typically had their own processor board for the LCD and an encoder for the touch screen. This meant two serial connections and not much to do for the system uC. The fact that is was two serial connections did present a wee problem though and we sometimes needed a mux for that.
It looks like I might be able to get my hands on a 320x240 monochrome display using the SED1335 controller chip (not sure of other details yet). I have seen many examples of this using an 8051, has anyone had any success using other uCs? If I do use a PIC, it will something with a little horsepower from the 18F series.
snipped-for-privacy@gmail.com (Brian Kidney) wrote in news: snipped-for-privacy@posting.google.com:
Hi Brian,
I'm currently working on an control-interface for an 640x480 stn color lcd. As I didn't have any knowledge on driving such lcds before, I had to learn a lot. Depending on the size of your lcd microcontrollers like pic or atmega will be to "small". It starts with the ammount of ram they provide. Just calculate the memory needed to represent one frame on your display. The other side is the timing for driving the lcd. It might be possible to do with fast microcontrollers, but not even easy. There are some controller-chips out there which are able to interface lcds directly. I currently work on an EPSON S1D13A04, which does the whole driving/interfacing timing of the lcd. It has buildin RAM and some graphics-functions. Just have a look at the datasheet for details. On the other side it has some kind of "universal" host-controller interface, which you are able to connect to a wide range of microcontrollers/cpus. My project for example is based on a Freescale/Motorola ColdFire.
Using a touchscreen is another story. There are touchscreens with mainly three different interfaces out there: 4-wire, 5-wire and 8-wire. Second they differ in technology, which will also require a different controller. Most touchscreen are resistive. There also exist a lot of controller chips or even ready controller boards which can be interfaced to RS232 or USB for example. National provides such controller chips with LM8300/LM8500. As I know 3M manufactures controllers boards. There are also a few other manucatureres of those chips/board. If you have some knowledge of electronic engineering and some programming skills it will be easy to build your own touchscreen controller with a microcontroller with buildin a/d converter, as resistive touchscreens are really easy to measure/interface. You will find some of the offerend ready controller chips aren't anymore than a standard microcontroller with builtin adc. As I use a touchscreen in my project too, I use an Atmel ATmega16 to interface between touchscreen and host.
In principle you could use almost any microcontroller. But why not take a look at some of the others out there? AVR, MSP430, ARM. Perhaps something like the Philips LPC2138. Buy a low-cost development board and hook it up to the display. Good community supported free tools (including C compilers) are available for all the families mentioned.
Why don't you use one of our iLCD modules? They have touch screen included and allow you make your project within days instead of months - they have graphic support included and you may use any (Windows) font stored in the flash memory of the module.
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