Trouble getting Peter's CWriter to work on Waveshare 1.14" display

[donmerchant]

I've searched around and different setups I've tried don't work. All I get is a blank dark display. I know it works as the Waveshare demo works fine. I'm trying to get larger font text on the display. Hopefully someone here can help me out.

Here's my latest:

#import machine
from machine import Pin, SPI
import gc
from writer import CWriter
import freesans20  # Font to use

from drivers.st7789.st7789_4bit import *
SSD = ST7789

gc.collect()  # Precaution before instantiating framebuf
# Conservative low baudrate. Can go to 62.5MHz.
spi = SPI(1, 30_000_000, sck=Pin(10), mosi=Pin(11), miso=None)
pcs = Pin(9, Pin.OUT, value=1)
prst = Pin(12, Pin.OUT, value=1)
pbl = Pin(13, Pin.OUT, value=1)
pdc = Pin(8, Pin.OUT, value=0)

ssd = SSD(spi, height=135, width=240, dc=pdc, cs=pcs, rst=prst, disp_mode=LANDSCAPE, display=TDISPLAY)

# Define a few colors
GREEN = SSD.rgb(0, 255, 0)
RED = SSD.rgb(255,0,0)
BLACK = SSD.rgb(0, 0, 0)

# Demo drawing geometric shapes using underlying framebuf methods
rhs = ssd.width -1
ssd.line(rhs - 20, 0, rhs, 20, GREEN)
square_side = 10
ssd.fill_rect(rhs - square_side, 0, square_side, square_side, GREEN)

# Instantiate a writer for a specific font
wri = CWriter(ssd, freesans20)  # Can set verbose = False to suppress console output
CWriter.set_textpos(ssd, 0, 0)  # In case a previous test has altered this
wri.setcolor(RED, BLACK)  # Colors can be set in constructor or changed dynamically
wri.printstring('Testing')
ssd.show()

Here's the terminal output:

>>> %Run -c $EDITOR_CONTENT
Orientation: Horizontal. Reversal: False. Width: 240. Height: 135.
Start row = 0 col = 0
>>> 

[peterhinch]

The problem arises because this display driver uses 4-bit color. Creating a color involves populating a lookup table: in your script the LUT is un-initialised so all colors are black. This is discussed in the nano-gui docs here.

The simplest approach is to use and import the colors.py file which creates a number of colors and also shows how you can create your own. You also need the boolpalette.py in the drivers directory. The following script works here, with directory paths amended to match the nanogui directory structure.

from machine import Pin, SPI
import gc
from gui.core.writer import CWriter
import gui.fonts.freesans20 as freesans20 # Font to use
from gui.core.colors import *

from drivers.st7789.st7789_4bit import *
SSD = ST7789

gc.collect()  # Precaution before instantiating framebuf
# Conservative low baudrate. Can go to 62.5MHz.
spi = SPI(1, 30_000_000, sck=Pin(10), mosi=Pin(11), miso=None)
pcs = Pin(9, Pin.OUT, value=1)
prst = Pin(12, Pin.OUT, value=1)
pbl = Pin(13, Pin.OUT, value=1)
pdc = Pin(8, Pin.OUT, value=0)

ssd = SSD(spi, height=135, width=240, dc=pdc, cs=pcs, rst=prst, disp_mode=LANDSCAPE, display=TDISPLAY)

# Demo drawing geometric shapes using underlying framebuf methods
rhs = ssd.width -1
ssd.line(rhs - 20, 0, rhs, 20, GREEN)
square_side = 10
ssd.fill_rect(rhs - square_side, 0, square_side, square_side, GREEN)

# Instantiate a writer for a specific font
wri = CWriter(ssd, freesans20)  # Can set verbose = False to suppress console output
CWriter.set_textpos(ssd, 0, 0)  # In case a previous test has altered this
wri.setcolor(RED, BLACK)  # Colors can be set in constructor or changed dynamically
wri.printstring('Testing')
ssd.show()

[donmerchant]

Thanks Peter. It works. I've also been working with the Waveshare 2" Pico display and finally got that working and understanding your code. Thanks again. Great work!

[peterhinch]

Glad it's sorted, I'll revisit the writer docs which were written before the advent of 4-bit drivers.