HELP.

While working on my BEAST build, I had soldered the Camera output to the CAM pad on the iFlight BEAST 55A AIO flight controller. I caught the wire on something and pulled the pad from the FC. Although I attempted to repair the pad, that was not successful. 

I need to remap a UART pad on the FC for the CAM input.

Post #13 of the iFlight BEAST thread has all of the Betaflight files attached and decent picture of the BEAST flight controller.

The attached graphic shows the wiring diagram. As per one of TMac's options for faster satellite acquisition, I am powering the GPS with an external 5V BEC.

TX1-RX1 is at the top right corner above the block of pads.
TX2-RX2 is inside the connector where the Rx receiver is wired.

UART1 = Open
UART2 = Open
UART3 = Rx Receiver
UART4 = VTX Tramp/SmartAudio
UART5 = is not listed in the Betaflight Ports Tab
UART6 = ? Can't find Tx-Rx pads.
UART7 = GPS
UART8 = ?  Can't find Tx-Rx pads.

Unfortunately the camera input can't be remapped because it isn't controlled by and doesn't go through the MCU. If you are unable to locate / scrape back the trace that went to the CAM pad then your only other option is to direct solder a wire to the appropriate pin on the OSD chip. This is the large rectangular 28-pin MAX7456 chip on the board next to the grey inductor with "100" written on it. On the iFlight Beast H7 55A AIO they use a Chinese clone of that chip called the AT7456E but it has exactly the same pinout as a MAX7456. See the image below.

You need to solder to pin #22 (VIN). EDIT: Please see the correction in post #5.

HI Snow,

Thank you very much. I really appreciate your assistance.

Thank you for providing options even though remapping is not possible. Hardwiring also works for me. 

I will first try to reconnect at the pad location.
If that doesn't work, I will try directly connecting to the Chip.

Thanks

Just to confirm that I have the correct chip and pin.

Yes, that's the correct chip. One correction however is that you won't be soldering directly to pin #22, but instead to the other side of a 0.1uF capacitor which is connected to that pin. So you need to trace which capacitor on the board has continuity from one side of it with pin #22 on the AT7456E ISD chip. You then need to solder to the other side of that capacitor. It's likely to be one of the capacitors (beige coloured components) close to the OSD chip.

Hi Snow,

Check the attached graphic and see if I understood you correctly.

My presumption is that it goes between the capacitor and the resistor; or maybe it doesn't matter?

Thanks

Doesn't matter. Between the resistor/cap or before the resistor, the circuit is the same.

The caps are usually bigger than the resistors so the best and easiest place to solder a wire to is to the end of the cap itself.

Well, here is a close up picture of the OSD Chip and pull off pad space. 

As you can see, the traces appear to be embedded in the layers of the PCB, so very little chance of getting a connection there. 

Not sure I can get in there, but can I attach directly to the cap (on the right side)    If I can get my paws in there   

Now, here's a thought...

What about running the feed through an external capacitor between the camera feed and the pin on the OSD chip. 

I think that I have the best chance soldering directly to the pin on the OSD chip.   

Snow, voodoo, others...What do you think 

If you connect to the VIN pin (pin #22) on the AT7456E OSD chip, in addition to the 0.1uF capacitor, you are also going to need to add a 75Ω resistor to ground. So you will effectively have to replicate that sub-circuit off the board. Below is a magnified area of the circuit for the MAX7456 / AT7456E that you will need to rebuild off the circuit.

(21-Dec-2020, 02:04 PM)SnowLeopardFPV Wrote: If you connect to the VIN pin (pin #22) on the AT7456E OSD chip, in addition to the 0.1uF capacitor, you are also going to need to add a 75k resistor to ground. So you will effectively have to replicate that sub-circuit off the board. Below is a magnified area of the circuit for the MAX7456 / AT7456E that you will need to rebuild off the circuit.

Hi Snow,

Presumably, I can ground it to any ground pad on the FC.

Ok, one more question {I think}. The CVBS IN; is that just where the video input {wire} connects?  The diagram also shows a ground there, but is that ground just for sheilding on the input? So, I don't need to ground at that point since I will only have a single wire attaching to that part of the circuit? 

I have already found a source for the capacitor and the resistor. I am waiting on some 40 gauge magnet wire to use for the connection to the pin on the OSD chip. Now, I am looking for a small circuit board for that assembly rather than just leave things hanging. 

This looks more and more like the best workable solution.

I  REALLY  appreciate your help on this. You are AMAZING  

Thank You

No problem  

Please note that I corrected my previous post where I inadvertently typed 75k instead of 75Ω. That now reads correctly.

You can connect the other side of the resistor to any ground pad on the FC. The ground for CVBS IN is just the shielding as you already suggested so you don't need to worry about that. Just twist the ground and signal wire from the camera together (twisted pair) which will help to mitigate any external interference on the signal wire.

Obviously it goes without saying that you need to be really careful soldering a wire to that pin because the pin next to it (pin #21) is supplied with 5V so you want to try and avoid shorting that to the VIN pin because it may not tolerate 5V being injected into it.

I wonder if the resistor is the one left of the T4 pad in your photo? Can you get in there?

(21-Dec-2020, 04:33 PM)voodoo614 Wrote: I wonder if the resistor is the one left of the T4 pad in your photo? Can you get in there?

Hi voodoo,

No, don't think I can, even with a "needle" tip on the iron. It is just too small of a space and too tiny of a component. I can barely see it even with +6.0 reading glasses. Although it looks pretty big in that pic, fact is that image is zoomed in quite a bit; both optically with the camera and then again with the graphic software. 

In fact, the largest thing that I have available is the actual pin on the OSC chip; yeah, even that is pretty tiny. I might actually have to buy a microscope in order to work on this thing.  

Having examined the board every which way with my +6.0 glasses and using optical and software magnification, I believe the best approach is to build the additional circuitry and connect it directly to Pin 22 on the OSD chip. Probably, my best chance at success.

I really appreciate all of your help and suggestions. 

Thanks