Recent model WaveShare hats have a different ST7789 screen

[jdlcdl]

Today in the "SeedSigner Devs" telegram group, User "BitK" shared info learned from speaking to WaveShare reps in Korea about late-model screens being too bright, then BitK shared a cut/paste of ST7789 code recomendations after referring WafeShare reps to review seedsigner's code base.

After white-space cleanup, the diff with changes and current release for src/seedsigner/hardware/ST7789.py is below

diff -a --strip-trailing-cr /tmp/BitK-ST7789.20250411 ~/seedsigner/src/seedsigner/hardware/ST7789.py

48c48
<         self.data(0x00)                 #self.data(0x00)
---
>         self.data(0x70)                 #self.data(0x00)
61c61
<         self.data(0x00) 
---
>         self.data(0x35) 
64c64
<         self.data(0x3F)
---
>         self.data(0x19)
73c73
<         self.data(0x0D)   
---
>         self.data(0x12)   
86,103c86,87
<         self.data(0xF0)
<         self.data(0x00)
<         self.data(0x02)
<         self.data(0x01)
<         self.data(0x00)
<         self.data(0x00)
<         self.data(0x27)
<         self.data(0x43)
<         self.data(0x3F)
<         self.data(0x33)
<         self.data(0x0E)
<         self.data(0x26)
<         self.data(0x2E)
< 
< 
<         self.command(0xE1)
<         self.data(0xF0)
<         self.data(0x07)
---
>         self.data(0xD0)
>         self.data(0x04)
104a89,95
>         self.data(0x11)
>         self.data(0x13)
>         self.data(0x2B)
>         self.data(0x3F)
>         self.data(0x54)
>         self.data(0x4C)
>         self.data(0x18)
107,110c98,107
<         self.data(0x16)
<         self.data(0x26)
<         self.data(0x43)
<         self.data(0x3E)
---
>         self.data(0x1F)
>         self.data(0x23)
> 
>         self.command(0xE1)
>         self.data(0xD0)
>         self.data(0x04)
>         self.data(0x0C)
>         self.data(0x11)
>         self.data(0x13)
>         self.data(0x2C)
112,115c109,115
<         self.data(0x19)
<         self.data(0x19)
<         self.data(0x31)
<         self.data(0x3A)
---
>         self.data(0x44)
>         self.data(0x51)
>         self.data(0x2F)
>         self.data(0x1F)
>         self.data(0x1F)
>         self.data(0x20)
>         self.data(0x23)
162c162
<         self._spi.writebytes2(pix) 
---
>         self._spi.writebytes2(pix)	
169c169
<         self._spi.writebytes2(_buffer) 
---
>         self._spi.writebytes2(_buffer)

[jdlcdl]

Noticing that the paste into telegram changed the source, BitK shared the py file... here changed to .txt

BitK-ST7789-20250411.txt

[kdmukai]

On my screen:

Original gamma curve (our current ST7789 driver) is too dark. Gray is too dark, orange renders too reddish.

        # Original settings
        self.command(0xE0)
        self.data(0xD0)
        self.data(0x04)
        self.data(0x0D)
        self.data(0x11)
        self.data(0x13)
        self.data(0x2B)
        self.data(0x3F)
        self.data(0x54)
        self.data(0x4C)
        self.data(0x18)
        self.data(0x0D)
        self.data(0x0B)
        self.data(0x1F)
        self.data(0x23)

        self.command(0xE1)
        self.data(0xD0)
        self.data(0x04)
        self.data(0x0C)
        self.data(0x11)
        self.data(0x13)
        self.data(0x2C)
        self.data(0x3F)
        self.data(0x44)
        self.data(0x51)
        self.data(0x2F)
        self.data(0x1F)
        self.data(0x1F)
        self.data(0x20)
        self.data(0x23)

---

The newer st7789_mpy driver ends up a bit too light, the orange gets a bit too washed out, but is a closer to match to our UX design target:

    # uses a different command setting format
                                            # Set gamma curve positive polarity
    ( b'\xe0', b'\xd0\x00\x02\x07\x0a\x28\x32\x44\x42\x06\x0e\x12\x14\x17', 0),
                                            # Set gamma curve negative polarity
    ( b'\xe1', b'\xd0\x00\x02\x07\x0a\x28\x31\x54\x47\x0e\x1c\x17\x1b\x1e', 0),

# Converted to the ST7789 driver format:
        self.command(0xE0)
        self.data(0xd0)
        self.data(0x00)
        self.data(0x02)
        self.data(0x07)
        self.data(0x0a)
        self.data(0x28)
        self.data(0x32)
        self.data(0x44)
        self.data(0x42)
        self.data(0x06)
        self.data(0x0E)
        self.data(0x12)
        self.data(0x14)
        self.data(0x17)

        self.command(0xE1)
        self.data(0xd0)
        self.data(0x00)
        self.data(0x02)
        self.data(0x07)
        self.data(0x0a)
        self.data(0x28)
        self.data(0x31)
        self.data(0x54)
        self.data(0x47)
        self.data(0x0e)
        self.data(0x1c)
        self.data(0x17)
        self.data(0x1b)
        self.data(0x1e)

---

The curve in the "BitK" attachment above is even brighter with the orange rendering closer to yellow:

        self.command(0xE0)
        self.data(0xF0)
        self.data(0x00)
        self.data(0x02)
        self.data(0x01)
        self.data(0x00)
        self.data(0x00)
        self.data(0x27)
        self.data(0x43)
        self.data(0x3F)
        self.data(0x33)
        self.data(0x0E)
        self.data(0x0E)
        self.data(0x26)
        self.data(0x2E)

        self.command(0xE1)
        self.data(0xF0)
        self.data(0x07)
        self.data(0x0D)
        self.data(0x0D)
        self.data(0x0B)
        self.data(0x16)
        self.data(0x26)
        self.data(0x43)
        self.data(0x3E)
        self.data(0x3F)
        self.data(0x19)
        self.data(0x19)
        self.data(0x31)
        self.data(0x3A)

---

A "goldilocks" gamma curve isn't quite present, but the st7789_mpy gets the closest for my screen.

We should probably offer at least these three curves to be options in Settings.

Nice to have: get a more precise middle curve for what we assume to be the majority of screens.