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smiller29
USA
Asked
Resolved by DJ Sures!
OK guys I have another question for everyone can you use the UART on the EZB V4 to connect to a USB rather than the camera port?
I want to hardwire my EZB's to my onboard PC but I also want to use my ez-robot camera with one of my EZB V4.
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- Confirmed PL2303TA USB-TTL adapter is rated to a maximum 6Mbaud of communication speed
- Confirmed that the USB-TTL adapter is working using remote echo
- LED on the camera is on but doesn't blink, this is normal for V2 camera, I believe only the Camera v1 blinked during communication
- I confirmed that the camera does work by connecting it directly to an EZ-Bv4, double-checked the LED was solid while working
- Tried multiple V2 cameras with different firmware versions (Green LED versus Blue)
- Tried swapping TX/RX in case of mislabelling
- Tried tying RTS and CTS to GND in separate tests
- Tried lowering the communication speed (COM4:115200) but it didn't have an effect
Here are the two errors I get depending on which way TX/RX are connected:
@DJ any ideas?
1) the baudrate isn’t supported and the data is unreadable and garbled
2) there’s too many missing because the converter can’t keep up so the packets and the header can’t be found. or there’s too much noise on the line. Although you’d think at least one header would be detected
Did you happen to try that?
Just a guess on my part.
@Herball yeah I was mostly testing at the default speed (ex:COM4) without the additional baudrate added.
-I went with the revision "D", the PL2303HDX, because I knew it would be running on Win 10 (for drivers).
-Voltage supplied was 3.3v
-Post #36 was the final wiring diagram that I got it to work.
-Once I had a video feed I got "ripped frames" where the feed seemed to lose sync between frames.(post #37)
-That was resolved by moving to a new computer and therefore a newer USB socket. All my issues went away after that. Not sure why that was. (post #48)
I have these in all my robot heads and they work great. Hope this helps?!
Can I ask you if you are using the latest version of ARC with the PL2303HXD, just to rule out if there's something in the software that's different?
Well I'm starting to suspect it's my Laptop at this point. I have tried force switching different COM ports, verifying that I truly have 3.3V powering the camera (I do), tried another USB port, did continuity checks on all the connected GNDs (all good), tried 2 different FDTI FT232RL adapters (at lower baudrate COM8:115200), and tried messing around with connecting RTS/CTS to GND on the adapter side, I can't seem to get it to work. Is there a setting I'm missing somewhere maybe? Do I need flow control on?
Changing the baud rate by specifying it (i.e., COM8:11500) will never work. This is because the camera transmits at 3,333,333 baud, not 115,200.
uart serial requires both parties involved in the communication to have the same baud. The baudrate is how fast the two devices transmit and receive. If one is not at the same baud as the other, there’s no way either can understand each other.
this is because one is speaking a different speed than the other. They need to speak the same speed or it’ll never work.
what’s happening with your setup is there’s data, but it’s skipping bytes or being garbled. That could be due to a slower USB port or the uart usb converter.
the ARC parser is looking for a header which is EZIMG. It needs to find those 5 characters. Then the next 2 bytes is the packet size as an unsigned int.
if the data is missing bytes or garbled, it’ll never find the text EZIMG and therefore just continue receiving what ever data is on the wire.
If you want to test it at a different baud rate, then use an esp32 cam with the firmware I made a few months ago. There’s a version of the esp32 cam that replaces the ezrobot camera and can connect directly to an ezb. But rather than connecting it to an ezb, just connect it to your uart adapter.
In that firmware, you can change the baudrate to what ever you want including 115200
*Edit: Yeah thinking more about it, I feel that it's likely the advertised baud rate of the PL2303TA is likely not up 6Mbaud, or maybe it is under very strict circumstances. The PL2303GC and PL2303HXD are rated to go to 12Mbaud so that's much higher than 3.3Mbaud, I have much more faith that those will work.
Hopefully, you have better luck with a newer laptop like I did, or get yourself the PL2303HXD or a completely different brand. Although I did have trouble finding one that was that high of baud. (maybe more avail now i think that was back in 2017/2018?)
Good luck!
I just don't want you to pull your hair out on this on my account...
After investing in 3 different USB-to-TLL adapters and doing quite the hack to the third one, which was supposed to be a USB-to-RS-232 adapter, today I was finally successful!
The only PL2303HXD chip I could find available was on an RS-232 adapter so I had to make it work. I removed the RS-232 chip and ohmed out the pads where the PL23203HXD RX, TX, and GND pins went to and soldered on some jumpers. I connected everything like Will did, except that I didn't even need to attach the camera RTS to GND, and it worked right away. All I had to do is to connect to COM3 in the camera skill and the picture appeared. It even looked great! No artifacts. Nice and crispy!
So word to the wise the FT232RL, PL2303HXA, and PL2303TA UART-to-TTL adapters aren't able to communicate at the 3.33 Mbaud needed by the EZ-camera but it seems that the only UART-to-TTL chip that can is the PL2303HXD (and possibly the PL2303GC - untested).
Thanks to everyone who contributed, and Will who originally posted the tutorial!