david_prentice:
The instructions are in the showBMP_not_Uno sketch.
If you have a question, quote the instruction that you do not understand.
This will help me to improve the instructions.
Especially for non-English speakers but improvements for Brits / Americans would be good too.
David.
Hello David,
To get back to the annoying topic of running TFT's for UNOs on MEGAs. I'm doing a little project where I was supposed to use this TFT with an UNO - but then the need to use softwareserial popped up - now the UNO is out the window, in with the mega. I connected the wiring as you mentioned earlier in this post and the display works like a dream, as quick as on the UNO. Problem is the touch screen. The touch screen works well on the UNO but no response on the MEGA.
Please tell me there's something I can do to get the touch screen going on the mega...
RM68140 320x480 ID=0x6814. Picture below.
Think about it. The calibration sketch is designed for the shield. So it only diagnoses data pins on 2-9 and A0-A5.
If you have moved data pins to 22-29 on the Mega, you need to map the Uno diagnosed pins.
E.g. if XP, YM were diagnosed on 6,7 they would now be 28, 29.
It looks very painful to connect lots of jumper cables. I would make a proper Adapter with a Protoshield.
If you map data to 22-29 and SD pins to 50-52, the TFT, Touch and SD will work fast and efficiently.
David.
David, another question on this same TFT - I just loaded an exact copy of a sketch on a second identical tft screen (picture in post #21) but the area where touch work is notably smaller on the bottom of the second screen, I guess with about 5mm.
Loaded touch_shield_kbv and sure enough, one can clearly see the difference when painting lines along the edges.
Is this software related? Same chip, according to the serial output:
Found unknown LCD driver
ID=0x6814
Screen is 320x480
Calibration is:
LEFT = 920 RT = 150
TOP = 940 BOT = 120
Wiring is: SWAPXY
YP=55 XM=56
YM=29 XP=28
What's this all about?
Please use the TouchScreen_Calibr_native sketch from the v2.9.8 examples on a Uno.
Copy-paste the debug output from the Serial Terminal.
It is not uncommon for Touch Panels to be a bit vague in one corner. I doubt that many people ever notice.
Most apps use "buttons" which are not very critical. A Paint sketch might follow the stylus over the screen. A calibrated screen should give you a perfect point. But possibly with one missing corner.
David.
I tried that, and changed the pins to this: int XP = 28, YP = A1, XM = A2, YM = 29; since I'm using it on a MEGA.
Says "broken screen" in small font in the middle of the screen, Serial output:
TouchScreen.h GFX Calibration
MTouchScreen.h GFX Calibration
Making all control and bus pins INPUT_PULLUP
Typical 30k Analog pullup with corresponding pin
would read low when digital is written LOW
e.g. reads ~25 for 300R X direction
e.g. reads ~30 for 500R Y direction
BROKEN TOUCHSCREEN
ID = 0x6814
If you have a DMM you can measure the resistance in the normal way.
A single crack in the Touch glass will render it "broken".
A fellow member sent me a Red 0x6814 shield. The Touch works ok.
I presume that the screen in #0 is a 3.5" Blue ILI9481. It does not have a Touch Panel.
You can recognise Touch Panels by a 4-way ribbon with gold printed traces. Sometimes with printed icons.
David.
Hi David,
When using my 3.5" MCUfriend touch tft it suddenly started registering fake "touches" on the bottom left corner, seems to be at random time intervals. I thought the MIN_PRESSURE may be too low causing the touch feature to be too sensitive, but increasing that value even up to 500 from the default 20 made no difference.
Any idea what this can be? Any test I can run to try and debug this issue?
Thanks,
Hein
There will always be occasional glitches. I did not write the TouchScreen.h library. I would prefer a different algorithm for processing a "valid" touch. e.g. median from 5 readings.
But you can always do some processing of your own. e.g. has the touch registered in the same place for several milliseconds?
This is pretty easy to do with buttons. Not so easy if you are drawing a work of Fine Art.
David.
david_prentice:
But you can always do some processing of your own. e.g. has the touch registered in the same place for several milliseconds?
Is there a sketch in the examples that can tell me where and for how long it was pressed for?
To answer my own question above, I revisited my 3.5" MCUfriend touch screen and getting phantom screen touches every now and then. This is the code I inserted in the loop, just before the touch screen conditions. It forces a wait of 120ms before a touch is registered as a real touch.
boolean tapped;
unsigned long newTapTime;
int tapSensitivity = 120;
void loop
{
if ((tp.z > MINPRESSURE) && (tp.z < MAXPRESSURE) && !tapped) // NEW TAP
{
tapped = true;
newTapTime = millis();
}
if (!(tp.z > MINPRESSURE && tp.z < MAXPRESSURE) && (millis() - newTapTime > tapSensitivity)) // NO TAP
{
tapped = false;
realTouch = false;
}
if (tapped && millis() - newTapTime > tapSensitivity)
{
Serial.println(F("<<< REAL TOUCH >>>"));
realTouch = true;
}
else
realTouch = false;
if (realTouch)
{
..... rest of touch screen directions here.
A simpler method is to configure the Touch library to make multiple reads.
Or you make the multiple reads yourself. Then wait for N identical reads.
Think about your keyboard. You only accept a keypress that has a steady state for 20ms or so. i.e. a reasonable time for a typist but long enough to debounce the key.
If you wait for 180ms it will appear sluggish response.
YMMV.
David.
