Flashing DevKitC from external Serial Converter

[uberrice]

Hey guys.

So, I want to flash my DevKitC as a test from an external Serial Converter, namely the ESP-PROG which works on the basis of the FT2232. However, it doesn't connect. I suspect this is because of insufficient power supply when only supplying through the FT2232. However, then again if I power the DevKitC from the USB Port, the DevKitC's serial converter also powers up. This is a problem, as 2 UART chips will likely interfere.

Anyways, I can't get it to upload over external UART. I tried supplying 3V3 from an Arduino UNO I had lying around connected to the mains via USB wall charger, however this wasn't enough. I suspect it would work if I was to power it from the 3v3 pin directly, but I do currently not have any 3v3 PSU just lying around.

Any workarounds - anyone experienced this before?

I'm specifically not getting across the "connecting...--" step, so I guess it has not enough juice to boot into programming mode.

[mikemoy]

How are you going to program your DevKitC with the ESP-PROG when the DevKitC has its own onboard programmer circuit?
You can't have 2 circuits trying to program the same device.

[WiFive]

Are you manually putting it in download mode with the buttons?

[uberrice]

How are you going to program your DevKitC with the ESP-PROG when the DevKitC has its own onboard programmer circuit?
You can't have 2 circuits trying to program the same device.

Yes, the onboard serial converter is pulling down the RX/TX signals when it's active. Which is why I tried disabling it by only supplying the ESP with 3.3V. I was hoping to somehow go around it. I'm trying to do this to test whether serial programming works with the ESP-PROG for a custom board that won't have an onboard serial converter.

Are you manually putting it in download mode with the buttons?

I am, but it doesn't connect. I expect that is either because the 3.3V supply isn't enough from just the ESP-PROG or the other sources i tried, or the serial converter either pulls down TX signals even when inactive or it also gets turned on by the 3v3 supply. Honestly, it isn't a "doesn't work" issue. I'm merely trying to test whether I can use the ESP-PROG to program an ESP because I'm gonna build a custom board that won't have its own serial converter.