I just bought a new computer with a big AMD CPU, but the motherboard only outputs VGA and I have no VGA cables anymore.
I do have an oscilloscope though.
So I can simply read the data out of the scope, like so:
This is what the vsync and hsync lines look like zoomed in:
and what two scan lines of data look like:
The full code to extract the frame:
import siglent_funcs as sf
def load_and_display():
directory_path = '/home/asdf/Downloads/'
bin_files = glob.glob(os.path.join(directory_path, '*.bin'))
fn = max(bin_files, key=os.path.getmtime)
print(f"loading {fn}")
with open(fn, 'rb') as f:
dt, volts = sf.extract_data(f)
vsync, hsync, _, color = volts
vsync_pulse = vsync - np.mean(vsync)
vsync_pulse = np.diff(vsync_pulse, append=[vsync_pulse[-1]])
frame_boundaries, _ = signal.find_peaks(vsync_pulse, height=0.02)
assert(frame_boundaries.size == 2)
volts = volts[:, frame_boundaries[0]:frame_boundaries[1]]
vsync, hsync, _, color = volts
hsync_pulse = hsync - np.mean(hsync)
hsync_pulse = np.diff(hsync_pulse, append=[hsync_pulse[-1]])
hline_boundaries, _ = signal.find_peaks(hsync_pulse, height=0.035)
manual_sz = int(np.median(np.diff(hline_boundaries)))
new_sz = volts.shape[1] - volts.shape[1] % manual_sz
volts = volts[:, 0:new_sz]
vsync, hsync, _, color = volts
image = color.reshape((-1, manual_sz))
plt.figure(figsize=(40, 40))
plt.imshow(image, interpolation='none', aspect='auto')
plt.show()
And the results:
Ta-da!
…It takes like 30sec to get a new image, but much better than nothing. I was able to get video over to the graphics card with it, at least.
It’s also interesting navigating the bios. Lots of the menu items are arranged vertically which then translates to later in time looking at it live on the scope. So to some extent you can know what you are choosing.