It's easy to use the PiCowbell DVI with CircuitPython and the PicoDVI core module. This module has been added to CircuitPython as of 8.1.0b2 - but note that it uses a lot of memory so in particular if you want to use Pico W with WiFi support, you'll likely only be able to get away with monochrome display.
Wiring
Plug the PiCowbell into a Pico board using headers according to the instructions on the Assembly pages. Then, plug a mini HDMI to HDMI adapter with an HDMI cable into the PiCowbell mini HDMI port.
CircuitPython Usage
To use with CircuitPython, you need to first install the PicoDVI dependencies into the lib folder onto your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file.
Connect your Pico board to your computer via a known good data+power USB cable. The board should show up in your File Explorer/Finder (depending on your operating system) as a flash drive named CIRCUITPY.
Extract the contents of the zip file, and copy the entire lib folder, the Helvetica-Bold-16.pcf font file, blinka_computer.bmp bitmap file and code.py file to your CIRCUITPY drive.
Your CIRCUITPY/lib folder should contain the following folders and file:
- adafruit_bitmap_font/
- adafruit_display_shapes/
- adafruit_display_text/
- simpleio.mpy
Hello World DVI Output Example
Once everything is saved to the CIRCUITPY drive, you can connect the PiCowbell to an HDMI monitor and connect your Pico to USB power. You'll see the Hello World example display on the screen.
# SPDX-FileCopyrightText: 2023 Liz Clark for Adafruit Industries
# SPDX-FileCopyrightText: Adapted from Phil B.'s 16bit_hello Arduino Code
#
# SPDX-License-Identifier: MIT
import gc
import math
from random import randint
import time
import displayio
import picodvi
import board
import framebufferio
import vectorio
import terminalio
import simpleio
from adafruit_bitmap_font import bitmap_font
from adafruit_display_text import label, wrap_text_to_lines
from adafruit_display_shapes.rect import Rect
from adafruit_display_shapes.circle import Circle
from adafruit_display_shapes.roundrect import RoundRect
from adafruit_display_shapes.triangle import Triangle
from adafruit_display_shapes.line import Line
# check for DVI Feather with built-in display
if 'DISPLAY' in dir(board):
display = board.DISPLAY
# check for DVI feather without built-in display
elif 'CKP' in dir(board):
displayio.release_displays()
fb = picodvi.Framebuffer(320, 240,
clk_dp=board.CKP, clk_dn=board.CKN,
red_dp=board.D0P, red_dn=board.D0N,
green_dp=board.D1P, green_dn=board.D1N,
blue_dp=board.D2P, blue_dn=board.D2N,
color_depth=8)
display = framebufferio.FramebufferDisplay(fb)
# otherwise assume Pico
else:
displayio.release_displays()
fb = picodvi.Framebuffer(320, 240,
clk_dp=board.GP12, clk_dn=board.GP13,
red_dp=board.GP10, red_dn=board.GP11,
green_dp=board.GP8, green_dn=board.GP9,
blue_dp=board.GP6, blue_dn=board.GP7,
color_depth=8)
display = framebufferio.FramebufferDisplay(fb)
bitmap = displayio.Bitmap(display.width, display.height, 3)
red = 0xff0000
yellow = 0xcccc00
orange = 0xff5500
blue = 0x0000ff
pink = 0xff00ff
purple = 0x5500ff
white = 0xffffff
green = 0x00ff00
aqua = 0x125690
palette = displayio.Palette(3)
palette[0] = 0x000000 # black
palette[1] = white
palette[2] = yellow
palette.make_transparent(0)
tile_grid = displayio.TileGrid(bitmap, pixel_shader=palette)
group = displayio.Group()
def clean_up(group_name):
for _ in range(len(group_name)):
group_name.pop()
gc.collect()
def show_shapes():
gc.collect()
cx = int(display.width / 2)
cy = int(display.height / 2)
minor = min(cx, cy)
pad = 5
size = minor - pad
half = int(size / 2)
rect = Rect(cx - minor, cy - minor, size, size, stroke = 1, fill=red, outline = red)
tri = Triangle(cx + pad, cy - pad, cx + pad + half, cy - minor,
cx + minor - 1, cy - pad, fill=green, outline = green)
circ = Circle(cx - pad - half, cy + pad + half, half, fill=blue, stroke = 1, outline = blue)
rnd = RoundRect(cx + pad, cy + pad, size, size, int(size / 5), stroke = 1,
fill=yellow, outline = yellow)
group.append(rect)
group.append(tri)
group.append(circ)
group.append(rnd)
rect.fill = None
tri.fill = None
circ.fill = None
rnd.fill = None
time.sleep(2)
rect.fill = red
tri.fill = green
circ.fill = blue
rnd.fill = yellow
time.sleep(2)
clean_up(group)
del rect
del tri
del circ
del rnd
gc.collect()
def sine_chart():
gc.collect()
cx = int(display.width / 2)
cy = int(display.height / 2)
minor = min(cx, cy)
major = max(cx, cy)
group.append(Line(cx, 0, cx, display.height, blue)) # v
group.append(Line(0, cy, display.width, cy, blue)) # h
for i in range(10):
_n = simpleio.map_range(i, 0, 10, 0, major - 1)
n = int(_n)
group.append(Line(cx - n, cy - 5, cx - n, (cy - 5) + 11, blue)) # v
group.append(Line(cx + n, cy - 5, cx + n, (cy - 5) + 11, blue)) # v
group.append(Line(cx - 5, cy - n, (cx - 5) + 11, cy - n, blue)) # h
group.append(Line(cx - 5, cy + n, (cx - 5) + 11, cy + n, blue)) # h
for x in range(display.width):
y = cy - int(math.sin((x - cx) * 0.05) * float(minor * 0.5))
bitmap[x, y] = 1
group.append(tile_grid)
time.sleep(2)
clean_up(group)
def widget0():
gc.collect()
data = [31, 42, 36, 58, 67, 88]
num_points = len(data)
text_area = label.Label(terminalio.FONT, text="Widget Sales", color=white)
text_area.anchor_point = (0.5, 0.0)
text_area.anchored_position = (display.width / 2, 3)
group.append(text_area)
for i in range(11):
_x = simpleio.map_range(i, 0, 10, 0, display.width - 1)
x = int(_x)
group.append(Line(x, 20, x, display.height, blue))
_y = simpleio.map_range(i, 0, 10, 20, display.height - 1)
y = int(_y)
group.append(Line(0, y, display.width, y, blue))
prev_x = 0
_prev_y = simpleio.map_range(data[0], 0, 100, display.height - 1, 20)
prev_y = int(_prev_y)
for i in range(1, num_points):
_new_x = simpleio.map_range(i, 0, num_points - 1, 0, display.width - 1)
new_x = int(_new_x)
_new_y = simpleio.map_range(data[i], 0, 100, display.height - 1, 20)
new_y = int(_new_y)
group.append(Line(prev_x, prev_y, new_x, new_y, aqua))
prev_x = new_x
prev_y = new_y
for i in range(num_points):
_x = simpleio.map_range(i, 0, num_points - 1, 0, display.width - 1)
x = int(_x)
_y = simpleio.map_range(data[i], 0, 100, display.height - 1, 20)
y = int(_y)
group.append(Circle(x, y, 5, fill=None, stroke = 2, outline = white))
time.sleep(2)
clean_up(group)
def widget1():
gc.collect()
data = [31, 42, 36, 58, 67, 88]
num_points = len(data)
bar_width = int(display.width / num_points) - 4
x_mapped_w = display.width + 2
h_mapped_h = display.height + 20
text_area = label.Label(terminalio.FONT, text="Widget Sales", color=white)
text_area.anchor_point = (0.5, 0.0)
text_area.anchored_position = (display.width / 2, 3)
group.append(text_area)
for i in range(11):
_y = simpleio.map_range(i, 0, 10, 20, display.height - 1)
y = int(_y)
group.append(Line(0, y, display.width, y, blue))
for i in range(num_points):
_x = simpleio.map_range(i, 0, num_points, 0, x_mapped_w)
x = int(_x)
_height = simpleio.map_range(data[i], 0, 100, h_mapped_h, 0)
height = int(_height)
group.append(vectorio.Rectangle(pixel_shader=palette, width=bar_width,
height=display.height + 1, x=x, y=height, color_index = 2))
time.sleep(2)
clean_up(group)
def text_align():
gc.collect()
TEXT = "hello world"
text_area_top_left = label.Label(terminalio.FONT, text=TEXT, color=red)
text_area_top_left.anchor_point = (0.0, 0.0)
text_area_top_left.anchored_position = (0, 0)
text_area_top_middle = label.Label(terminalio.FONT, text=TEXT, color=orange)
text_area_top_middle.anchor_point = (0.5, 0.0)
text_area_top_middle.anchored_position = (display.width / 2, 0)
text_area_top_right = label.Label(terminalio.FONT, text=TEXT, color=yellow)
text_area_top_right.anchor_point = (1.0, 0.0)
text_area_top_right.anchored_position = (display.width, 0)
text_area_middle_left = label.Label(terminalio.FONT, text=TEXT, color=green)
text_area_middle_left.anchor_point = (0.0, 0.5)
text_area_middle_left.anchored_position = (0, display.height / 2)
text_area_middle_middle = label.Label(terminalio.FONT, text=TEXT, color=aqua)
text_area_middle_middle.anchor_point = (0.5, 0.5)
text_area_middle_middle.anchored_position = (display.width / 2, display.height / 2)
text_area_middle_right = label.Label(terminalio.FONT, text=TEXT, color=blue)
text_area_middle_right.anchor_point = (1.0, 0.5)
text_area_middle_right.anchored_position = (display.width, display.height / 2)
text_area_bottom_left = label.Label(terminalio.FONT, text=TEXT, color=purple)
text_area_bottom_left.anchor_point = (0.0, 1.0)
text_area_bottom_left.anchored_position = (0, display.height)
text_area_bottom_middle = label.Label(terminalio.FONT, text=TEXT, color=pink)
text_area_bottom_middle.anchor_point = (0.5, 1.0)
text_area_bottom_middle.anchored_position = (display.width / 2, display.height)
text_area_bottom_right = label.Label(terminalio.FONT, text=TEXT, color=white)
text_area_bottom_right.anchor_point = (1.0, 1.0)
text_area_bottom_right.anchored_position = (display.width, display.height)
group.append(text_area_top_middle)
group.append(text_area_top_left)
group.append(text_area_top_right)
group.append(text_area_middle_middle)
group.append(text_area_middle_left)
group.append(text_area_middle_right)
group.append(text_area_bottom_middle)
group.append(text_area_bottom_left)
group.append(text_area_bottom_right)
time.sleep(2)
clean_up(group)
def custom_font():
gc.collect()
my_font = bitmap_font.load_font("/Helvetica-Bold-16.pcf")
text_sample = "The quick brown fox jumps over the lazy dog."
text_sample = "\n".join(wrap_text_to_lines(text_sample, 28))
text_area = label.Label(my_font, text="Custom Font", color=white)
text_area.anchor_point = (0.0, 0.0)
text_area.anchored_position = (0, 0)
sample_text = label.Label(my_font, text=text_sample)
sample_text.anchor_point = (0.5, 0.5)
sample_text.anchored_position = (display.width / 2, display.height / 2)
group.append(text_area)
group.append(sample_text)
time.sleep(2)
clean_up(group)
del my_font
gc.collect()
def bitmap_example():
gc.collect()
blinka_bitmap = displayio.OnDiskBitmap("/blinka_computer.bmp")
blinka_grid = displayio.TileGrid(blinka_bitmap, pixel_shader=blinka_bitmap.pixel_shader)
gc.collect()
group.append(blinka_grid)
time.sleep(2)
clean_up(group)
del blinka_grid
del blinka_bitmap
gc.collect()
def sensor_values():
gc.collect()
text_x = "X: %d" % randint(-25, 25)
text_y = "Y: %d" % randint(-25, 25)
text_z = "Z: %d" % randint(-25, 25)
x_text = label.Label(terminalio.FONT, text=text_x, color=red)
x_text.anchor_point = (0.0, 0.0)
x_text.anchored_position = (2, 0)
y_text = label.Label(terminalio.FONT, text=text_y, color=green)
y_text.anchor_point = (0.0, 0.0)
y_text.anchored_position = (2, 10)
z_text = label.Label(terminalio.FONT, text=text_z, color=blue)
z_text.anchor_point = (0.0, 0.0)
z_text.anchored_position = (2, 20)
group.append(x_text)
group.append(y_text)
group.append(z_text)
for i in range(40):
if i == 10:
group.scale = 2
elif i == 20:
group.scale = 3
elif i == 30:
group.scale = 4
x_text.text = "X: %d" % randint(-50, 50)
y_text.text = "Y: %d" % randint(-50, 50)
z_text.text = "Z: %d" % randint(-50, 50)
time.sleep(0.1)
time.sleep(0.1)
clean_up(group)
group.scale = 1
display.root_group = group
while True:
show_shapes()
sine_chart()
widget0()
widget1()
text_align()
custom_font()
bitmap_example()
sensor_values()
This example is a port of the Arduino 16bit_hello code written by Phil B. with some slight variation to show off some of the unique abilities of displayio.
The example begins by showing a rectangle, circle, triangle and rounded rectangle and changing the fill attribute from None to a color.
Then, a few chart variations are shown, including a sine wave pattern, line graph and bar graph.
Next is a text alignment example, showing how to use the anchor_point and anchor_position functions in the adafruit_display_text library.
Following that is a custom text example, loading a bitmap font instead of the built-in terminalio font.
Then there is a quick break from fonts to show off a bitmap image, specifically Blinka happily using her computer.
Finally, an example shows how to update the text in a Label object for projects where you want to display text information that updates over time.
It's important to note that the example code is optimized to be able to run all of the examples in a loop, which you more than likely won't want to do for your projects. As a result, the clean_up(group) function is run after each example to use pop() to remove all of the graphical elements of the displayio group. Garbage collection (gc.collect()) is also run to conserve memory. Additionally, each graphical element is created and deleted each time in each of the functions.
If you were to run, for example, the sensor_values() function on its own for a project, you would instantiate the graphical elements once, before the loop, and then update the text with the "values" in the loop:
...
text_x = "X: %d" % randint(-25, 25)
text_y = "Y: %d" % randint(-25, 25)
text_z = "Z: %d" % randint(-25, 25)
x_text = label.Label(terminalio.FONT, text=text_x, color=red)
x_text.anchor_point = (0.0, 0.0)
x_text.anchored_position = (2, 0)
y_text = label.Label(terminalio.FONT, text=text_y, color=green)
y_text.anchor_point = (0.0, 0.0)
y_text.anchored_position = (2, 10)
z_text = label.Label(terminalio.FONT, text=text_z, color=blue)
z_text.anchor_point = (0.0, 0.0)
z_text.anchored_position = (2, 20)
group.append(x_text)
group.append(y_text)
group.append(z_text)
while True:
for i in range(40):
if i == 10:
group.scale = 2
elif i == 20:
group.scale = 3
elif i == 30:
group.scale = 4
x_text.text = "X: %d" % randint(-50, 50)
y_text.text = "Y: %d" % randint(-50, 50)
z_text.text = "Z: %d" % randint(-50, 50)
time.sleep(0.1)
Text editor powered by tinymce.
