TheBackShed.com

Forum Index : Microcontroller and PC projects : Touch not working on WaveShare RP2350-Touch-LCD-3.5-C module

Author

Message

Canada_Cold
Regular Member

Joined: 11/01/2020
Location: Canada
Posts: 53

Posted: 03:13pm 25 Apr 2026

Copy link to clipboard

Print this post

Hi,
I have a WaveShare RP2350-Touch-LCD-3.5-C module. This is a 2350B with ST7796 LCD and a FT6336 touch controller. The LCD works great. However, each time I try to setup the Touch option and calibrate (GUI CALIBRATE) the touch the system locks up.
The info is here - https://docs.waveshare.com/RP2350-Touch-LCD-3.5
The schematic - https://files.waveshare.com/wiki/RP2350-Touch-LCD-3.5/RP2350-Touch-LCD-3.5.pdf

Here is the sequence I’m using, am I doing something wrong?

>
> option reset
> option list
PicoMite MMBasic RP2350B V6.02.00
OPTION FLASH SIZE 16777216
OPTION COLOURCODE ON
OPTION PICO OFF
OPTION CPUSPEED (KHz) 200000
>
> OPTION SYSTEM SPI GP18,GP19,GP16
> OPTION LCDPANEL ST7796S,RL,GP20,GP23,GP21,GP22,INVERT
>
>
> GUI TEST LCDPANEL
(The GUI test runs OK)
>
> OPTION SYSTEM I2C GP34, GP35
> OPTION TOUCH FT6336 GP24, GP25
> GUI CALIBRATE

(At this point I now have the first target on the screen and the message “Touch Target and Hold”. The system is now locked up and a power cycle is required to get it restarted.)

PicoMite MMBasic RP2350B V6.02.00
Copyright 2011-2025 Geoff Graham
Copyright 2016-2025 Peter Mather

> option list
PicoMite MMBasic RP2350B V6.02.00
OPTION SYSTEM SPI GP18,GP19,GP16
OPTION SYSTEM I2C GP34,GP35
OPTION FLASH SIZE 16777216
OPTION COLOURCODE ON
OPTION PICO OFF
OPTION CPUSPEED (KHz) 200000
OPTION LCDPANEL ST7796S, RLANDSCAPE,GP20,GP23,GP21,GP22,INVERT
OPTION TOUCH FT6336 GP24,GP25,,50
>
> print MM.INFO$(TOUCH)
Ready
>
>

Any help would be appreciated. Or any suggestions on other testing I should do to debug the issue.

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 8781

Posted: 03:47pm 25 Apr 2026

Copy link to clipboard

Print this post

That's a capacitive touch screen. I *think* it's supported now - the only one that is IIRC. Leave the extra arguments off the OPTION TOUCH.
Edited 2026-04-26 01:54 by Mixtel90

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

mozzie
Senior Member

Joined: 15/06/2020
Location: Australia
Posts: 284

Posted: 04:17pm 25 Apr 2026

Copy link to clipboard

Print this post

G'day Canada,
These are quite a nice display unit.

Try LIST SYSTEM I2C first and see if you get a response at address &H38, this is the touch controller so needs to respond, if not check wiring.

The TOUCH INTERRUPT pin must be working (GP24 in your system), this is a green wire on the unit I have here. If this isn't working you will not get a response from the touch calibration.

Good Luck.

Regards, Lyle.

Print this page

To reply to this topic, you need to log in.