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Forum Index : Microcontroller and PC projects : RP2350-Touch-LCD-2.8
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| ehewlett Newbie  Joined: 14/02/2025 Location: CanadaPosts: 9 |
I've just acquired two RP2350-Touch-LCD-2.8 boards from Waveshare, and have put PicoMite BASIC on them, and am loving them. Unfortunately, however, the touchscreen on them is capacitative, rather than resistive - well, fortunately, really, but UNfortunately because I'm unable to get the touchscreens working on them on PicoMite BASIC... probably because they are capacitative. Here's my OPTION LIST: PicoMite MMBasic RP2350A Edition V6.00.03 OPTION SYSTEM SPI GP10,GP11,GP12 OPTION SYSTEM I2C GP6,GP7 OPTION FLASH SIZE 16777216 OPTION COLOURCODE ON OPTION PICO OFF OPTION CPUSPEED (KHz) 150000 OPTION LCDPANEL CONSOLE OPTION DISPLAY 20, 40 OPTION LCDPANEL ST7789_320, LANDSCAPE,GP14,GP15,GP13,GP16 OPTION TOUCH GP17,GP18 OPTION SDCARD GP24, GP19, GP20, GP21 And here's the link to the Waveshare wiki page on the device: https://www.waveshare.com/wiki/RP2350-Touch-LCD-2.8 OPTION PICO is OFF because the RP2350 chip is built in, and setting PICO OFF makes GP24 available to the SDCARD. My biggest hope is to somehow get the touchscreens working under PicoMite BASIC. Any help in this regard that anyone might be able to offer would be much appreciated! I seem to sort of have gotten touch working with "OPTION SYSTEM I2C GP6,GP7" and then "OPTION TOUCH GP17,GP18", but when I use the "GUI CALIBRATE" command, it gets the first touch fine but errors out on the second touch with the error message, "Touch hardware failure 4095,4095,4095,4095". ChatGPT's diagnosis of the problem is that my board 'uses a CST328 capacitive controller over I²C, not SPI. It never drives MISO, and it doesn’t understand the SPI commands PicoMite is sending. So when GUI CALIBRATE runs, PicoMite asks the SPI touch chip for coordinates, gets all 1s (0xFFF = 4095), and reports a “hardware failure.”' Has anyone else tried to get PicoMite BASIC working on one of these boards? If so, any luck with the touchscreen? Or is support for capacitative touch on the drawing board for an upcoming version of PicoMite BASIC? Edited 2025-10-01 14:17 by ehewlett |
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phil99 Guru  Joined: 11/02/2018 Location: AustraliaPosts: 2782 |
Can only find one supported:- Edited 2025-10-01 14:44 by phil99 |
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| ehewlett Newbie Joined: 14/02/2025 Location: CanadaPosts: 9 |
Hmm... I see. Thanks! I missed that option. The touch chip, however, is clearly CST328 over I2C. I'll see if by some chance the option is compatible with my unit's chip... maybe there's a consistent method of communication with capacitative touch chips. What do you think the odds are that the FT6336 and the CST328 are compatible? |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2782 |
You would need to download the data sheets to compare them. Or, as you indicated just give it a go. First remove the resistive touch with OPTION TOUCH DISABLE. |
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| ehewlett Newbie Joined: 14/02/2025 Location: CanadaPosts: 9 |
Sigh. No such luck. The command OPTION TOUCH FT6336 GP17,GP18 returns the following error message: Guess my next option is to dive into the data sheets. I've also glanced at the C code for PicoMite BASIC on the GitHub repo, but that's intimidating... especially since I don't know C! But knowing there's something in there for the FT6336 capacitative touch chip at least gives me something to look for... |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2782 |
LIST SYSTEM I2C should at least tell you what it's address is (in HEX). |
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IanT Senior Member  Joined: 29/11/2016 Location: United KingdomPosts: 114 |
My memory is not what it was but I seem to recall setting up my Waveshare 2.8" for touch when it first arrived (just to test it) but I was using a Pico 1 (directly plugged in) at that time. It is currently set-up with a new Pico 2 (on a Quad Extender) but I haven't enabled 'Touch' because I don't need it for current uses. I'm away at the moment but can try it on return if you've not resolved your issue by then... Regards, IanT |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10493 |
The Waveshare displays I've got all have resistive touch screens using the XPT2046 which has been around forever, seems to be ubiquitous for resistive touch and is of course fully supported by MMBasic. There seem to be an unending variety of capacitive touch controllers - all different - and some extremely difficult to drive (GT911) which makes it impossible to support all of them in MMbasic. I added the FT6336 because it is fairly common and very simple to drive but the driver won't work with any of the other controllers (including another FT variant). The only thing I can suggest with a controller like the CST328 is to write the handler in Basic if you can find how. It's simply not possible to add all these different controllers to MMbasic. I already have more TFT displays sitting in a box that I bought to add support than I know what to do with.  |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1579 |
Another job for Claude?  |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1579 |
The manual is too big to upload but Claude requests: |
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| ehewlett Newbie Joined: 14/02/2025 Location: CanadaPosts: 9 |
Wow! A reply from the great Peter Mather himself! (Thanks, Peter. Big fan here!) That’s about as definitive as it gets, I guess. Unfortunately for me, it’s a definitive no. I totally understand, of course. I remember back in the days of the TRS-80 Color Computer, someone lamenting, in an edition of the Rainbow Magazine dedicated to printers, how frustrating it was to support every new printer that came on the market. I’d offer to send you a RP2350-Touch-LCD-2.8, ‘cause it’s such a nice piece of kit, but I don’t want to add to your frustration - or your box of discarded touchscreens! I’m not a hardware guy - and, despite that, I actually have a working PS2/VGA PicoMite, for which I learned to solder and soldered myself, as well as two HDMI/USB PicoMites (since JCLPCB had a minimum order of two boards at the time), because I love BASIC and I love what you guys are doing. My hope, as not-a-hardware-guy, was that the RP2350-Touch-LCD-2.8 could be the platform for my project of porting my favourite BASIC game to a PicoMite, as it not only has capacitative touch, but also has a battery charging circuit built in - and it’s only about $30CAD. I’ve been at this project for a while now, chronicling the ups and downs of it on my blog. https://blog.ehewlett.net/2025/02/stellar-distractions-building-boot-to.html https://blog.ehewlett.net/search/label/Stellar%20Empires I’ve finally got my basic port up and running (haven’t done a post on that yet), and was hoping to move to adapting the interface for touchscreen, which seemed the most promising route to go - and still does, given the challenges of keyboard input on the Pico. (Plus, my vision is for a self-contained portable BASIC gaming device.) Maybe I’ll just have to go back to my old resistive touch Waveshare screens, which inspired the project. Or maybe I’ll have to get Claude to help me. ChatGPT volunteered to write me a handler for the touchscreen in BASIC, but what it gave me was an unusable mess. I have enough experience programming in other languages, that I also figure I might be able to do C, if I could figure out how and where the various drivers are in Peter and Geoff’s codebase on GitHub (especially now that I know that one does exists for one capacitative screen!), but if a BASIC subroutine will do, I suppose that would be the easier way to go. Anyhow, thanks for the help and feedback everyone. Reminds me of the “good old days” of BBSs and discussion boards! Any further help and suggestions would also be greatly appreciated! Edited 2025-10-02 01:37 by ehewlett |
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| Arne Newbie Joined: 05/01/2025 Location: GermanyPosts: 39 |
Hello, I played in the past with this touchscreen. Here you can find my test program based on the datasheet. Due it is multitouch I implemented „2 fingers“ only. TouchTST.zip Have Fun, Arne |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4096 |
If you still have hardware issues (USB / reset / ...) you might like to put them on here (new thread?) as people here may be able to figure what's wrong. John |
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| ehewlett Newbie Joined: 14/02/2025 Location: CanadaPosts: 9 |
Thank you all, and especially, thanks to Arne for his code. His test program got me started, as I saw it was detecting touches and doing something... although I wasn't entirely sure how it was working. So, following PhenixRising's suggestion, I turned to Claude. I began by uploading the code Arne provided and asking Claude how it worked. Eventually I thought to download and add the Python library for interacting with the CST328 touch-controller chip on the RP2350-Touch-LCD-2.8. That was actually the breakthrough, as the Python library contained everything Claude needed to "know" the specs for writing the touch-handler code, but Arne's code still came in handy, as it gave Claude the lead it needed to debug its own code. For anyone out there using this screen, here is the touch-handler that Claude wrote: 'Initialize touch controller reset pin (GP17) SetPin gp17, dout Pin(gp17) = 1 Pause 10 Pin(gp17) = 0 Pause 10 Pin(gp17) = 1 Pause 100 'Setup interrupt on GP18 SetPin gp18, intb, SUB_TEST 'Main loop Do Loop Sub SUB_TEST 'Check if there are any touch points (register 0xD005) I2C2 write &H1A,0,2,&HD0,&H05 I2C2 read &H1A,0,1,touch_flag num_touches = touch_flag And &H0F If num_touches = 0 Then Exit Sub 'Read first byte to validate I2C2 write &H1A,0,2,&HD0,&H00 I2C2 read &H1A,0,1,byte0 If (byte0 And &H0F) <> &H06 Then Exit Sub 'Read first touch point coordinates I2C2 write &H1A,0,2,&HD0,&H01 I2C2 read &H1A,0,1,byte1 'X low byte I2C2 write &H1A,0,2,&HD0,&H02 I2C2 read &H1A,0,1,byte2 'Y low byte I2C2 write &H1A,0,2,&HD0,&H03 I2C2 read &H1A,0,1,byte3 'X/Y high nibbles I2C2 write &H1A,0,2,&HD0,&H04 I2C2 read &H1A,0,1,pressure 'Calculate coordinates (already in screen pixels) x_pixel = (byte1 * 16) Or ((byte3 And &HF0) / 16) y_pixel = (byte2 * 16) Or (byte3 And &H0F) Print "Touch at pixel: X=";x_pixel;" Y=";y_pixel;" Pressure=";pressure End Sub And then here's a program I wrote to test out its interaction with some of the Color Computer emulation code (the PRINTAT function is replicating TRS-80 CoCo BASIC's PRINT @ X,"" command, where X is a text screen position from 0 to 511 - or 0 to 479 on this device's 32x15-line screen) that I'm using in my Stellar Empires porting project: Font 4 Sub PRINTAT loc, text$, fgColour If fgColour=0 Then fgColour=RGB(black) locY = Int(loc/32) locX = loc - (locY*32) locY = locY * 16 locX = locX * 10 Text locX, locY, text$, , , , fgColour End Sub 'Initialize touch controller reset pin (GP17) SetPin gp17, dout Pin(gp17) = 1 Pause 10 Pin(gp17) = 0 Pause 10 Pin(gp17) = 1 Pause 100 'Setup interrupt on GP18 SetPin gp18, intb, SUB_TOUCH Dim touch_char_x, touch_char_y, touch_detected CLS Do If touch_detected Then touch_detected = 0 PRINTAT touch_char_x + (touch_char_y * 32), "X", RGB(red) EndIf Pause 10 Loop Sub SUB_TOUCH I2C2 write &H1A,0,2,&HD0,&H05 I2C2 read &H1A,0,1,touch_flag num_touches = touch_flag And &H0F If num_touches = 0 Then Exit Sub I2C2 write &H1A,0,2,&HD0,&H00 I2C2 read &H1A,0,1,byte0 If (byte0 And &H0F) <> &H06 Then Exit Sub I2C2 write &H1A,0,2,&HD0,&H01 I2C2 read &H1A,0,1,byte1 I2C2 write &H1A,0,2,&HD0,&H02 I2C2 read &H1A,0,1,byte2 I2C2 write &H1A,0,2,&HD0,&H03 I2C2 read &H1A,0,1,byte3 x_pixel = (byte1 * 16) Or ((byte3 And &HF0) / 16) y_pixel = (byte2 * 16) Or (byte3 And &H0F) 'Convert pixels to character grid position (LANDSCAPE MODE) '320 pixels / 32 chars = 10 pixels per char (X axis uses the 320 dimension) '240 pixels / 16 rows = 15 pixels per row (Y axis uses the 240 dimension) touch_char_x = 31 - Int(y_pixel / 10) 'Note: y_pixel maps to X character position touch_char_y = Int(x_pixel / 15) 'Note: x_pixel maps to Y character position touch_detected = 1 End Sub |
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| ehewlett Newbie Joined: 14/02/2025 Location: CanadaPosts: 9 |
Note: For anyone interested in BASIC touch-handler, I have identified an error in the code. This will not matter much to anyone who simply uses it to identify pixel positions, but the FONT 4 selection is actually 16 pixels high, resulting in 15 rows of text on this device's 240-pixel high display. Hence the fourth-to-last line in the touch-handler should readtouch_char_y = Int(x_pixel / 16) and the corresponding comment in the line above should read '240 pixels / 15 rows = 16 pixels per row (Y axis uses the 240 dimension) Also, if anyone with any knowledge of this display knows how to tweak the touch-handler and/or the test code to detect when a touch is released, I'd very much appreciate some guidance. I've made this code work (with the above modification), but not being able to detect when a touch is released has made the implementation of touch controls more than a little challenging! |
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| Arne Newbie Joined: 05/01/2025 Location: GermanyPosts: 39 |
Hello, Here some expanded demo-code for the touch control with detailed comments. WS_28_Touch.zip Due I was lazy the evaluation of coordinates is implemented for 2 fingers only (can easy be expanded as needed; see comments in the program). Function of demo: - Draw with 1 finger on LCD - Draw with 2 fingers LCD - Clear LCD screen with 3 fingers - Show text on LCD with 4 fingers - Display raw data with 5 fingers With the possibility to use up to 5 fingers also gesture-operations can easy be implemented. P.S.: A.) With „OPTION AUDIO I2S GP2,GP4“ you have full sound support. B.) To the RTC: I was not able to set the correct year. Has anyone an Idea? Arne |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2782 |
Set Date$ and Time$ then:- RTC SETTIME DateTime$(now) or RTC SETTIME Date$+" "+Time$ And if you have a GPS module connected (and the time-zone with daylight saving configured) :- If GPS(Valid) then RTC SETTIME GPS(Date)+" "+GPS(Time) Edited 2025-10-19 19:07 by phil99 |
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| Arne Newbie Joined: 05/01/2025 Location: GermanyPosts: 39 |
Maybe I did not specify correctly… My problem is that if I set the year of the RTC to e.g. 2025 and then ask the date the year „2005“ is displayed, means that the correct date cannot be set to the RTC. It seems to be a problem with the RTC-chip implemented to the board (that mmBasic officially does not support). With the demo which came with the board the year (2024) was correct. I tried to set the year direct to the registers of the RTC but had no success. Maybe setting of date and time has to follow a specific sequence… Arne |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2782 |
Ok, that is a problem. This is a long shot but costs little to try - use a 2 digit year:- So:- RTC SETTIME "19/10/25 11:05" |
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