Should this work with a 3xRCA to AV cable? Getting video noise, no sound

[dvilelaf]

I'm trying to make the sketch work in a ESP32 mini, and since I do not have any composite video-capable devices at home, I'm trying a 3xRCA to AV cable. After a few seconds connected, I can see some noisy vertical lines and some noisy colors from time to time, but no sound. Not sure if it's a connection problem of if there is something I'm missing. Maybe I didn't understand the scheme.

What I've done:

• Solder positive of video cable to pin 25
• Solder negative of video cable to ground
• Solder both audio left and right positives to pin 26 through a 1k resistor (and set pin 26 as audio out in video_out.h)
• Solder both audio left and right negatives to ground through a 10nf capacitor

[cziter15]

Please note that these signals should be 75Ohm impedance matched. Do you have all shieldings connected to gnd?

Try this: To pin 25 - positive video (yellow), outer/shield directly to GND To pin 26 - throug capacitor 10uF to left and right positive audio, outer/shield directly to GND

Regards, Chris

niedz., 13 gru 2020 o 14:34 David Vilela [email protected] napisał(a):

I'm trying to make the sketch work in a ESP32 mini, and since I do not have any composite video-capable devices at home, I'm trying a 3xRCA to AV cable. After a few seconds connected, I can see some noisy vertical lines and some noisy colors from time to time, but no sound. Not sure if it's a connection problem of if there is something I'm missing. Maybe I didn't understand the scheme.

What I've done:

• Solder positive of video cable to pin 25
• Solder negative of video cable to ground
• Solder both audio left and right positives to pin 26 through a 1k resistor (and set pin 26 as audio out in video_out.h)
• Solder both audio left and right negatives to ground through a 10nf capacitor

[image: photo_2020-12-13_14-24-55] https://user-images.githubusercontent.com/1871782/102013285-51432e00-3d4f-11eb-8455-2d035ac67780.jpg

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/rossumur/esp_8_bit/issues/31, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABGFTPCNW54DMYITRJVRV6DSUS7ERANCNFSM4UZP4FVQ .

https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail Wolny od wirusów. www.avast.com https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

[dvilelaf]

@cziter15, I read here the following comment:

If you're having the same problem as me the capacitor goes on the negative of the audio line, not T'd off the positive like it seems to newbs.

That's why I soldered the audio L/R outter/negative/shielding through the capacitor to ground. So should I solder the capacitor to the positive then?

What about the resistor? The scheme lists a 1k resistor in the audio line. Should I remove it? I'm a little confused about the 750 ohm impedance matching.

    -----------
    |         |
    |      25 |------------------> video out
    |         |
    |      18 |---/\/\/\/----|---> audio out
    |         |     1k       |
    |         |             ---
    |  ESP32  |             --- 10nf
    |         |              |
    |         |              v gnd
    |         |
    |         |     3.3v <--+-+   IR Receiver
    |         |      gnd <--|  )  TSOP4838 etc.
    |       0 |-------------+-+   (Optional)
    -----------

This is how I have it:

Video positive/yellow cable -----------------------------------PIN 25
Video negative/outter cable ---------------------------------- GND
Audio L/R positives (red & white) -------- 1k resistor --------PIN 26
Audio L/R negatives/outter ---------- 10 nF capacitor ---------GND

[Martin-Laclaustra]

Verify that you are using the correct connections for your device on the other end. TRRS is far from being standardized: https://en.wikipedia.org/wiki/Phone_connector_(audio)#TRRS_standards

[dvilelaf]

Verify that you are using the correct connections for your device on the other end.

Interesting. How should I do that? The device is a cheap projector that has no instructions manual. Concerning the connections I listed on my last message, do you feel they're correct?

[dvilelaf]

I've tried with another ESP32 on a breadboard. I've tried plugging pin 25 to every of the 3 different lines and none seems to output a video signal. Surely I must be doing something very wrong.

[dvilelaf]

I can confirm that Bitluni CompositeVideo repository works with the actual cabling, and I can see the composite video demo. Still, esp_8_bit does not output video nor audio yet.

Edit: Corn64 fork also seems to output both video and audio (resoldering was needed due to TRRS), but as soon as my DualShock4 is detected in pairing mode, the program crashes.

[bootrino]

try changing the board type. I had video noise until I switched board type in the arduino IDE.

[CornN64]

You can not use pin 26 for audio! In fact both pin 25 & 26 outputs video and can't be changed to anything else. You'll need to use some other pin like the one suggested (pin 18 or reconfigure it to some other), the reason being that the second DAC can not be used when running the APLL at these frequencies and another scheme is used for audio (PWM modulator) and thus it will not be compatible with bitlunis wiring.