Use VGA setup for another project

[Martius108]

Hello,

I successfully created this project and wanted to use this Pico - VGA hardware configuration (because the VGA cable is soldered to my Pico W) for another project (Pong game). I tried to code this in MicroPython but could't get a VGA output. So I started to create a test file at first which looks like this - but still no signal on the screen. This code compiles without problems in Thonny and was saved to the Pico W as main.py so that it should run on boot. Could you please tell me what I'm doing wrong?

`from machine import Pin
import rp2
import time

VGA timing constants for 640x480@60Hz

H_ACTIVE = 640
H_FRONT_PORCH = 16
H_SYNC = 96
H_BACK_PORCH = 48
V_ACTIVE = 480
V_FRONT_PORCH = 10
V_SYNC = 2
V_BACK_PORCH = 33

@rp2.asm_pio(
out_init=rp2.PIO.OUT_LOW,
sideset_init=(rp2.PIO.OUT_HIGH,) * 2,
autopull=True,
pull_thresh=32,
fifo_join=rp2.PIO.JOIN_TX
)
def vga_program():
# Active video area
pull(block) .side(0b11)
out(x, 32) .side(0b11)
pull(block) .side(0b11)

label("active")
out(pins, 1)            .side(0b11)
jmp(x_dec, "active")    .side(0b11)

# Horizontal sync (simplified timing)
nop()                   .side(0b11)  # Front porch
nop()                   .side(0b01)  # HSYNC pulse
nop()                   .side(0b11)  # Back porch

Create a simple test pattern (white screen)

line_words = H_ACTIVE // 32
test_line = [0xFFFFFFFF] * line_words

Initialize pins

video_pin = Pin(18, Pin.OUT) # GPIO18 -> Physical Pin 24
vsync_pin = Pin(19, Pin.OUT) # GPIO19 -> Physical Pin 25
hsync_pin = Pin(21, Pin.OUT) # GPIO21 -> Physical Pin 27

Initialize state machine

sm = rp2.StateMachine(
0,
vga_program,
freq=125_000_000, # Run at maximum frequency
sideset_base=Pin(19),
out_base=Pin(18),
set_base=Pin(21)
)

print("Starting VGA output...")
sm.active(1)

Main loop with VSYNC handling

vsync_counter = 0
try:
while True:
# Output one complete frame
for line in range(V_ACTIVE):
# Send line data
for word in test_line:
sm.put(word)

    # Handle VSYNC
    vsync_counter += 1
    if vsync_counter >= V_ACTIVE + V_FRONT_PORCH + V_SYNC + V_BACK_PORCH:
        vsync_counter = 0
    
    # Set VSYNC signal
    if V_ACTIVE + V_FRONT_PORCH <= vsync_counter < V_ACTIVE + V_FRONT_PORCH + V_SYNC:
        vsync_pin.value(0)  # VSYNC active (low)
    else:
        vsync_pin.value(1)  # VSYNC inactive (high)
    
    time.sleep_us(31)  # Line timing

except KeyboardInterrupt:
sm.active(0)
print("Stopped")`

[evansm7]

No idea! But it looks like you're doing timing-sensitive stuff in Python -- I'd be impressed if it was anywhere near fast/predictable enough to do that. Even though C, it would be less frustrating to try this experiment in C I think... Good luck.

[Martius108]

Thanks. That was a stupid idea :) I didn't know that this kind of project can only be done with C.

[evansm7]

Ah but you don’t know until you try, experimenting is learning, and all that! (Who knows, maybe it’ll work :) but maybe worth trying it second :) :) )