Question on Hantouch HT043A-NCOFD52

Archive SparkFun Site Questions/Comments
1

Hi,

anyone played with this touch panel overlay? I was wondering if anyone knows if 4-wire resistive can support multitouch, or do you have to use optical touch panels for that?

thanks

'mark

2

You can’t do multitouch very well. You can sorta detect that there are two fingers pressed, but thats about it.

Just as an overview of how 4 wire resistive touch screens work:

You essentially have two big resistors overlaid on one another. The X resistor has its endpoints vertically at each end, and vice versa for the Y. When you touch the screen, you bridge the two resistors at the point you touch, with another resistor, labelled Rt below.

The following is an example with 1 point of contact.

X+            Y+
      
|              |
\              \
/   Rxp    Ryp /
\              \
/              /
|      Rt      |
+----/\/\/\----+
|              |
\              \
/              /
\   Rxm    Rym \
/              /
|              |

X-            Y-

From this you can determine the X/Y and pressure of contact; for example, drive X+ / X- with 5 + 0 respectively, and measure either Y+ or Y- to find the X point of contact, same deal for Y. You can then drive X+ and Y-. and measure Y+ and X- to get the Rt voltage drop, which is inversely proportional to pressure.

Effectively when you add a second touch point, you add a Rt2 in parallel, which decreases the Rt voltage drop below what you can normally get, even when pressing on the touchscreen extremely hard.

So in summary, you can detect multiple touches occuring, but not exactly where.

Cheers,

–David Carne

3

Where do I plug in the ribbon cable? I ordered one a week ago and it arrived today. i completely took apart my PSP, and I can’t find a spot to plug in the ribbon cable… the analog stick has 4 connectors, so i would probably plug it in there, but the ribbon cable is too short… help please?

4

Er… this product isn’t designed to be added to a PSP.

This product is named the PSP touchscreen simply because it has the same size as a standard PSP lcd, which we also carry. These products are designed to be used by electronics hobbyists / engineers in their own designs… not added to an existing PSP.

Cheers,

–David Carne

5

yay, i bought for no reason… :stuck_out_tongue:

… misleading item description.

6

We will happily do a refund on that item for you assuming its still in good condition [aka, has the original protective films on it / etc].

Contact spark@sparkfun.com if you want to do the return.

We have clarified the item description.

Cheers,

–David Carne