Touch Panels and Screens

[KansaiRobot]

Hello and thank you always.

Lately I have become interested in touch panels, and I am thinking of doing something related with this and PIC microprocessors.
However my knowledge of these is still very poor so I would appreciate some advice.

First, I have made some browsing and notice that there are either small (2.8, 3.5 , at most 7 inches) panels that can be controlled with say AVR micros or PICs, or there are big industrial solutions that I assume are completed products , so how can you integrate them to a more complex system...

Is my impression correct? If I were to require a medium size touch screen that I can use to do menu choosing and other finger commands, where can I find a list of available resources....

Thanks in advance for the help

 

[Ian Rogers]

The size plays no part!! There are several technologies.... Resistive / Capacitive Single point or multipoint.

The resistive 4 wire are the easiest to interface... The 5 wire and capacitive panels really need a controller... Multipoint needs a controller for sure... Most controllers with connect to a micro via a serial interface... The serial controllers can be very complex and allow you complete control without extra software.... There are some that just report touch and position, there are some that report touch, position and gesture!!

 

[MaxHeadRoom78]

ELO are one of the largest manuf of touch screens, it may be worth picking up one of the older RS232 resistive types rather than the USB type, I have never analyzed the data but if one were hooked up to a RS232 port the data could be analyzed when a touch is made using one of the serial capture programs to see if it is X/Y coordinates.
Max.

 

[nsaspook]

The older ELO serial (SmartSet controllers) CarrollTouch infrared technology is my basic workhouse for machine interfaces for clean rooms. It can't do all the fancy multi-touch stuff but for a basic operator interface they're hard to beat as they work with anything thing that breaks the XY beams and they work well with gloved fingers on a perfectly smooth and ultra-clean surface. Most of my work with them is to emulate some strange proprietary OEM touchscreen from a company that's been out of business for 10 years so we can have one standard screen with a PIC emulation controller to translate standard ELO codes to what the tool needs.
**broken link removed**
https://www.elotouch.com/products/touchscreens/CarrollTouch/default.asp

I've got a few hacker boxs to reverse-engineer the codes and a standard interface box for the tool interface.

Standard interface controller in shielded box.

Replaces the monster 19" CRT touchscreen that was once in this spot.

19" ELO LCD touchscreen.

 

[KansaiRobot]

The size plays no part!! There are several technologies.... Resistive / Capacitive Single point or multipoint.

The resistive 4 wire are the easiest to interface... The 5 wire and capacitive panels really need a controller... Multipoint needs a controller for sure... Most controllers with connect to a micro via a serial interface... The serial controllers can be very complex and allow you complete control without extra software.... There are some that just report touch and position, there are some that report touch, position and gesture!!

Thank you for your reply! I have research a bit about the resistive 4 wire. Already understood the gist of it. Now, if I were interested in controllers (and in panels models) could you give some notable examples?? and i they support touch position and/or gesture?

I read microchip has its own controllers too.

(note: when I ask you about examples, I am just asking for a link or resource, not pretending someone else do the research for me )

 

[KansaiRobot]

ELO are one of the largest manuf of touch screens, it may be worth picking up one of the older RS232 resistive types rather than the USB type, I have never analyzed the data but if one were hooked up to a RS232 port the data could be analyzed when a touch is made using one of the serial capture programs to see if it is X/Y coordinates.
Max.

analyze the data? doesn't the shape of these data come as specs of the products??

 

[nsaspook]

analyze the data? doesn't the shape of these data come as specs of the products??

It should but there are many variations of the serial codes and sub-modes in modes.
ELO has an old program to see what you have.
**broken link removed**
**broken link removed**

From the Linux serial touch driver

/*
* This driver can handle serial Elo touchscreens using either the Elo standard
* 'E271-2210' 10-byte protocol, Elo legacy 'E281A-4002' 6-byte protocol, Elo
* legacy 'E271-140' 4-byte protocol and Elo legacy 'E261-280' 3-byte protocol.
*/

 

[KansaiRobot]

I have been reading and it turns out Microchip has its own set of controllers: AR1000 and similars
and its own development kits called mTouch...

I am wondering if AVR has something similar...

 

[Ian Rogers]

I have been reading and it turns out Microchip has its own set of controllers: AR1000 and similars
and its own development kits called mTouch...

I am wondering if AVR has something similar...

mTouch is very complex... I looked at this and then left it alone.. The results you can get by reading a 4 wire interface directly with your own micro can be excellent.. I am using MikroC from MikroElektronika!! They have a builtin TFT touch driver.... It works for me and I can use the same driver to do small mono or large colour screens...

 

[KansaiRobot]

Yes, it seems so. I am a little confused, since on one hand it seems they rely on capacitive sensing only... and then I found one doc (havent read it yet) that says they handle resistive touch also....
Currently I am reading about CSM (Capacitive Sensing Module) but I think will go back to resistive touch next week .

The mikroElectronika resource you refer to... is this one **broken link removed**

or do you have any other link???


Also, can resistive support multitouch???

 

[Ian Rogers]

That's the one However!! They do a TFT_Touch library as well... That's the one I use

 

[Wade Hassler]

Nextion have an inexpensive HMI product in several, mostly-tiny sizes.
Be warned that the feature-set is ever-evolving, their English is not perfect, and you'll spend a half-day learning the content editor.
But... less than $15 gets you a 320x240 resistive touch-screen with a high-speed UART interface. (To name the part I've actually used.)

 

[KansaiRobot]

That's the one However!! They do a TFT_Touch library as well... That's the one I use

I found this video

in which the author uses mikroElectronica's MikroC to use a touch panel. I also noticed that he uses several TFT_ functions. I guess that is the library you refer...
Do you have to use their products? I ask this because in the video I see he uses a XPT2046 touch screen controller and a SSD1963 , so I dont see what is mikroElectronica there...

Can this libraries be used with other compilers... or the MPLABX IDE??

 

[Ian Rogers]

No! I don't use a controller.... I use the PIC32 direct... The pic reads the x, y and z... If you notice, the z is missing from the video.... When you detect z, you can stop all that jitter... I can draw far more precisely than that

 

[KansaiRobot]

No! I don't use a controller.... I use the PIC32 direct... The pic reads the x, y and z... If you notice, the z is missing from the video.... When you detect z, you can stop all that jitter... I can draw far more precisely than that

May I ask what is the LCD model and touch panel you use?? (Maker etc).

 

[Ian Rogers]

At the moment a 240 x 128 t6963c and a bog standard 4.8" 4 wire touch panel... **broken link removed**

Works just fine... The MikroC software driver is pretty good...

 

[KansaiRobot]

Thank you for your reply.
I am reading some more literature, and I wonder, in some examples the 4 wires of the panel go directly to the micro.
In other examples, they use some transistors to connect the micro pins to the 4 wires of the panel...

wonder why....

If there is no suitable reason, i plan to connect them directly.....

 

[Ian Rogers]

There are two ways to read the panel.... Hardware or software.. If you need speed then hardware will be slightly faster

BUT!! The pic32 samples very fast so it makes no difference to me... To read the X you power the Y plane and read any of the X connections... To read Y you power the X plane then read any of the Y connections..

To read Z you power one of the X connections and ground one of the Y connections the difference between the two remaining connections is the Z.. From this information you can work out the pins..

 

[KansaiRobot]

Nextion have an inexpensive HMI product in several, mostly-tiny sizes.
Be warned that the feature-set is ever-evolving, their English is not perfect, and you'll spend a half-day learning the content editor.
But... less than $15 gets you a 320x240 resistive touch-screen with a high-speed UART interface. (To name the part I've actually used.)

I am browsing through Nextion. Do their LCDs use controllers??? I am reaing datasheets etc (like https://wiki.iteadstudio.com/images/8/86/Datasheet_NX4827T048.pdf
or https://wiki.iteadstudio.com/NX4827T043 ) and it says nothing about it. I asked them directly and they just sent me the links... so I am not sure...

I am thinking controlless driving should be a pain so I am checking the controllers (if they use one) before purchasing. Any help greatly appreciated

 

[Ian Rogers]

That screen is what is known as an "Intelligent" screen... Very similar to4D systems... A string of RS232 data to run functions on the onboard GPU.... Functions and images are stored on the SD card, you can then instruct the screen when and where!!