(25-Aug-2021, 03:31 PM)kafie1980 Wrote: I don't see a 3.3v pad on that FC.

Any 5V and GND pad should work.

The only issue I can think of using 5V is that other devices such as your RC receiver may get powered on during the process and I am not sure if the ST-Link can provide enough current to power everything up.

I bought this one:

https://it.aliexpress.com/item/100500162...4c4dSdYzRE

Is it right ?

In that case i will temprary detach the 5V wire from the receiver, not an issue!

(25-Aug-2021, 03:35 PM)Zanna83 Wrote: I bought this one:

https://it.aliexpress.com/item/100500162...4c4dSdYzRE

Is it right ?

Yes, one like that is fine.

I read somewhere that some of the clones have some of the ST-Link V2 clones have their pinouts mislabelled, so keep that in mind. Before connecting it into the FC, check voltage outputs on the pins.

(25-Aug-2021, 03:52 PM)SnowLeopardFPV Wrote: I read somewhere that some of the clones have some of the ST-Link V2 clones have their pinouts mislabelled, so keep that in mind. Before connecting it into the FC, check voltage outputs on the pins.

This is what I mean. There are two different pin-outs for the clones and some of them had the wrong labelled case fitted on them for the circuit that was actually inside them. An easier way to check is to just pull the case off and check the silkscreen labelling on the actual circuit board to check that it matches the labelling on the outside of the case. I didn't realise the case came off so easy. Just grab the black plastic pin socket and the aluminium case simply just pulls off with a little bit of force. My one has the GND pins in the centre (pins 5 & 6), and the labelling on the case of mine does actually match that of the circuit board inside. So just check yours in the same way before using it.

With the clone ST-Link, most important thing is getting the 5v/3.3v/gnd pins identified so you don’t damage or burn anything.

Thank you both guys, will let you know.

On the discord group of Emuflight someone told me that in some rare cases to make the DFU recognizable by Windows you should detach all the uarts otherwise Impulse RC fixer, Zadig, etc. see multiple devices on that port.

(25-Aug-2021, 09:33 AM)kafie1980 Wrote: I have a similar issue with my Luminier Lux F7 ultimate FC and I have to disconnect the GPS to get it to flash firmware.

I have heard/read similar complaints about receivers connected to a specific uart. I think even JB mentioned something on his recent live streams.

I did mention to detach any devices connected to the UARTS.

Did you try this yet?

(26-Aug-2021, 10:13 AM)kafie1980 Wrote: I did mention to detach any devices connected to the UARTS.

Did you try this yet?

Yes I remeber your suggestion but I still have to try.

I can detach the JST connector to remove Caddx Vista. For CRSF, someone told me that it will be enought to put it in bind mode instead of detaching wires.

Ok, the DFU issue is solved!

Yesterday I desoldered the "5V" wire of CRSF from the flight controller. As soon as no devices were connected to UARTS the FC entered DFU mode with the "press the button and plug the cable" method. I've been able to flash Betaflight again over Emuflight.

Regarding the suggestion of avoiding to desolder any cable and put the CRSF in binding mode.... it does not work.

Out of interest, what UARTs do you have things connected to, and with everything connected to the FC are you able to get into DFU mode with Betaflight flashed to it (i.e. is getting into DFU mode only an issue with Emuflight flashed to the FC)?

(30-Aug-2021, 10:03 AM)SnowLeopardFPV Wrote: Out of interest, what UARTs do you have things connected to, and with everything connected to the FC are you able to get into DFU mode with Betaflight flashed to it (i.e. is getting into DFU mode only an issue with Emuflight flashed to the FC)?

UART 1: Caddx Vista
UART 3: CRSF
UART 7: ESC Telemetry

The one that seems to disturb DFU mode is CRSF.

Even with Betaflight installed it seems not to work with CRSF connected.

My Kakute F7 HDV (v1.4) was going into DFU mode just fine, but since I added GPS I haven't actually needed to do that. Guess which UART I stuck the GPS module on. Yep, it's on UART 3.

I'm away from home until the end of the week so I'll check when I get back. The only saving grace is that the GPS module is connected via a plug so I can simply just unplug it if I can't get into DFU mode with it connected instead of having to desolder it. My Crossfire receiver is on UART4 and my Air Unit MSP connection is on UART1. I haven't bothered configuring ESC Telemetry as it doesn't provide anything useful.

Same DFU issue with the GPS on my Lumenier Lux F7 ultimate but lucky it can be unplugged.

So I'm back home now and I just tested DFU mode with my GPS module connected to UART3 on my Kakute F7 HDV FC.

Nada. Unable to get into DFU mode. I unplugged the GPS module and I was then able to get into DFU mode no problem.

I did some further research and discovered that it is specifically UART1 and UART3 that cause this issue on F4, F7, and H7 FC's. So the takeaway from this is not to connect any peripherals to UART1 or UART3 on a F4/F7/H7 flight controller that power themselves up when a USB cable is connected to the FC, or if you do, make sure it's a peripheral that is connected via a plug so you can temporarily just unplug it if you need to get into DFU mode.

I thought it was FC specific. But seems like it is consistent when wired to specific uarts.

With a GPS we usually have the option to unplug but with an RX directly soldered this is a pain.

Good to know for future builds.

(03-Sep-2021, 11:47 PM)SnowLeopardFPV Wrote: So I'm back home now and I just tested DFU mode with my GPS module connected to UART3 on my Kakute F7 HDV FC.

Nada. Unable to get into DFU mode. I unplugged the GPS module and I was then able to get into DFU mode no problem.

I did some further research and discovered that it is specifically UART1 and UART3 that cause this issue on F4, F7, and H7 FC's. So the takeaway from this is not to connect any peripherals to UART1 or UART3 on a F4/F7/H7 flight controller that power themselves up when a USB cable is connected to the FC, or if you do, make sure it's a peripheral that is connected via a plug so you can temporarily just unplug it if you need to get into DFU mode.

Next time i will update i will try to move CRSF on UART2 or 4 to double check this issue. Will let you know!

In the meantime thank you for your support!