Need st7789 help.

[ccpetersen]

I have a Waveshare PicoLCD 1.14 which I'm trying to get working with an rpi pico or pico2. Both behave the same way. My code gets to the Config sections and blocks never to return.
``
package main

import (
"image/color"

"machine"

"time"

"tinygo.org/x/drivers/st7789"

)

// Define your specific pin assignments here
const (
SPI_SCK = machine.GP10 // clock
SPI_SDO = machine.GP11 // data
SPI_CS = machine.GP9 // select
LCD_DC = machine.GP8 // data/command
LCD_RST = machine.GP12 // reset
LCD_BL = machine.GP13 // lcd backlight
)

var display st7789.Device

func main() {

time.Sleep(time.Second * 2) // delay for monitor connections

println("  configure SPI...")

machine.SPI1.Configure(machine.SPIConfig{
	Frequency: 24_000_000, // Adjust frequency as needed
	SCK:       SPI_SCK,
	SDO:       SPI_SDO,
	Mode:      0,
})

println("  create st7789 driver instance...")

// Create ST7789 driver instance
display := st7789.New(machine.SPI1, LCD_RST, LCD_DC, SPI_CS, LCD_BL)

println("  configure display...")

// Configure display parameters
display.Configure(st7789.Config{
	Width:    135,
	Height:   240,
	Rotation: st7789.NO_ROTATION,
	//FrameRate: st7789.FRAMERATE_60,
	//RowOffset:    0,
	//ColumnOffset: 0,
})

println("  display configured...")

red := color.RGBA{255, 0, 0, 255}

// Example: Fill screen with a color
display.FillScreen(red)

time.Sleep(time.Second)
display.FillScreen(color.RGBA{0, 255, 0, 255})
time.Sleep(time.Second * 1)

// Example: Draw a string
//display.DrawText(10, 10, "Hello TinyGo!", st7789.WHITE, st7789.BLACK)

for {
	// Keep the program running
	time.Sleep(time.Second * 5)
	println("  sleeping...")
}

}
``

Any help would be much appreciated.

[squirrelbob]

I'm just guessing here, but comparing your code to mine, that is working fine with st7789, I can only see 2 differences:

1. I'm configuring these pins as outputs:

LCD_RST.Configure(machine.PinConfig{Mode: machine.PinOutput})
LCD_DC.Configure(machine.PinConfig{Mode: machine.PinOutput})
SPI_CS.Configure(machine.PinConfig{Mode: machine.PinOutput})
LCD_BL.Configure(machine.PinConfig{Mode: machine.PinOutput})

2. I'm using Frequency: 62_500_000, but 24_000_000 should probably also work just fine.

Otherwise your code looks good and should go pass the configuration step if there are no mechanical issues.

[ccpetersen]

I should have mentioned that my setup runs with Micropython and Circuitpython so it should be OK.

Looking in the driver the port setup is done in func NewOf() but I'll add your suggestion and see how it goes.

Thanks for your help

[ccpetersen]

Alas that didn't make any difference.

Thanks for taking the time to look.

[eliasnaur]

Can you try tinygo gdb or some other way to determine how far the driver initializes? I don't see where in Configure your code might block. You may be getting a panic somewhere, and TinyGo has a tendency to lock up before the panic reaches the output.

FWIW, you can clone tinygo-drivers and set up go.work (with go work use <your program module> <path/to/cloned/tinygo-drivers>) to enable local changes to the driver code.

[ccpetersen]

My bad, it's not blocking. I took out the "-monitor" in the command "tinygo flash -target=pico main.go" and the println() now it just exits after a time. Nothing on the display so I assume there is a panic after the config call in main.go.

I don't know how to use gdb so I'm stuck.

Thanks for your help.

[ccpetersen]

Update and new question: I've found a couple of st7789 drivers written in C so my projects can move forward.

In an effort to find out why I can't get the tineygo st7789 driver working I was going to use, as suggested here, gdb. So I tried this which didn't work. Main.go is the file above.
Can anyone tell me whats wrong?

tinygo gdb -target=pico main.go

Reading symbols from /tmp/tinygo2367773633/main...
:3333: Connection timed out.
"monitor" command not supported by this target.
You can't do that when your target is `exec'

[eliasnaur]

If you can get a C driver to work with TinyGo, I guess it's more productive to port that driver, or diff the Go and C driver to see what they're doing differently.

[ccpetersen]

Well I got as far as running a local copy of the driver. It was immediately clear that the first time sendCommand() is called it hangs on:
err := d.bus.Tx(d.cmdBuf[:1], nil) // line 225
I have gone through the init line by line so I'm fairly sure the problem is in machine.go. Probably in DMA or SPI handling. That's as far as I can go so maybe this helps someone.

[Gustavomurta]

I don't have this board = Waveshare PicoLCD 1.14.
wiki: https://www.waveshare.com/wiki/Pico-LCD-1.14

But I have an oscilloscope and a cheap logic analyzer. Using only the scope I was able to do several tests including this one, but only measuring the GPIO ports.I don't have the ST7899 display module yet.
https://github.com/tinygo-org/drivers/blob/release/examples/st7789/main.go

I think I've discovered the problem that's preventing your program from running correctly.
SPI-1 interface pins are already configured automatically and should not be specified.
I measured these lines and they appear to be correct now.

This is the program I ran, and it appears to be correct. Please test it and let us know the results.
You may need to adjust your display settings. I don't have a display and can't see it.

/*
Waveshare PicoLCD 1.14 - RP2040 Tinygo tests
Gustavo Murta 2025_08_13
tinygo version 0.38.0 windows/amd64 (using go version go1.24.2 and LLVM version 19.1.2)
https://github.com/orgs/tinygo-org/discussions/4983
tinygo flash -target pico main.go
C:\Users\jgust\tinygo\programas\Raspberry_Pico\st7789_TFT
wiki: https://www.waveshare.com/wiki/Pico-LCD-1.14
*/

package main

import (
	"image/color"
	"machine"
	"time"

	"tinygo.org/x/drivers/st7789"
)

// Define your specific pin assignments here
const (
	SPI_CS  = machine.GP9  // select
	LCD_DC  = machine.GP8  // data/command
	LCD_RST = machine.GP12 // reset
	LCD_BL  = machine.GP13 // lcd backlight
)

var display st7789.Device

func main() {

	time.Sleep(time.Second * 2) // delay for monitor connections

	println("  configure SPI...")

	machine.SPI1.Configure(machine.SPIConfig{
		Frequency: 24_000_000, // Adjust frequency as needed
		Mode:      0,
	})

	println("  create st7789 driver instance...")

	// Create ST7789 driver instance
	display := st7789.New(machine.SPI1, LCD_RST, LCD_DC, SPI_CS, LCD_BL)

	println("  configure display...")

	// Configure display parameters
	display.Configure(st7789.Config{
		Width:    135,
		Height:   240,
		Rotation: st7789.NO_ROTATION,
		//FrameRate: st7789.FRAMERATE_60,
		//RowOffset:    0,
		//ColumnOffset: 0,
	})

	println("  display configured...")

	for {
		// Keep the program running		
		display.FillScreen(color.RGBA{0, 255, 0, 255})
		time.Sleep(time.Millisecond * 500)
	}
}

[ccpetersen]

Right now my main.go looks like yours.

One of the issues I had with Pico-1.14 display is that the display reset is connected to GP12 which machine.SPI thinks is a great candidate for the SDI pin and machine.SPI will not allow you to change it. Configuring it later as a reset pin seems to enable the display bit it just shows a black rectangle on a background of color noise. The rectangle comes from the fillScreen(color.RGBA{0, 0, 0, 255}) // Clear screen around line 175 in the driver.

After that the display doesn't respond to any input and appears to be frozen.

I'm running the driver locally and it runs fine but the display just sits there with its black rectangle.

My guess right now is that the st7789 buffer is 320x240 and setWindow(), in the driver has a problem with the displays 240x135 width and height. Somewhere in the data being TXed to the st7789.

I've got the Driver loaded with println() statements but I haven't nailed down the problem. BTW I get the same results from the driver at tinygo/x/drivers so it's not a local issue.

I work on this as time allows but since it doesn't work its not a high priority. Still it would be nice to see progress. I'll have another go tonight.

Thanks for taking the time to look at this!

[Gustavomurta]

I don't think the RESET pin is causing any problems.
Wiki:
"RESX is the reset pin, it is pulled low when the module is powered on, usually set to 1;"

But if you notice that RESET is interfering with functionality, you can try creating a dedicated reset procedure.
(pin low, pin high).

I recommend you do this test (changing to SPI1 config and other pins):
https://github.com/tinygo-org/drivers/blob/release/examples/st7789/main.go

Please test it and let us know the results.

[ccpetersen]

Thanks.
Your code is the same I've be running with a couple of differences.

• I had to change to SPI1. Hardwired in the LCD
• You did not specify SCK, SDO, and SDI, but machine.SPI fills them in, no foul.
• Specifying SDI as the reset pin does not seem to cause any problems,
• You did not specify the LCD width and height. The driver then assumes 240,240.
• After these changes the display looks almost right except its missing the bottom of the display. RowOffset has no effect.
• It appears that the driver is happiest with a square lcd but the Pico-LCD is 240x135

Changing the width, height and the display has colors but is corrupt.

I f found an stt7789 driver that handles 320,240, 240x240, and 240x135 resolutions. I'll attempt to port it over to Tinygo in the next few nights.

I've also ordered a waveshare 240x240 lcd. Should be here in tomorrow for some more testing.

Onward and upward...