Hubsan h501s - additional ch. advanced TX

Hi everybody,
I am new here and if i am posting in wrong place, sorry, please correct me,

I just have read this topic www.deviationtx.com/forum/protocol-devel...hubsans?limitstart=0

but it is not 100% what i am looking for, but i am sure you guys are able to solve my doubts.

From few months i am thinking how to mount very light gimbal on H501s
I have watched a lot of YT videos where people are mounting regular gimbals to 501s, but in most of them the gimbal with camera is too heavy for 501s. Of course they are flying but not long and ESCs are hot as I suppose - this drone is not for carrying more than 100-120g additional weight....
So i decided to build very light gimbal with micro brushless motors
But iI also want to have possibility for control it by deafult advanced hubsan transmitter.

I am thinking is it possible to use free channel for it? It exist for sure in 501s with advanced transmitter -
advanced TX is the same as for Hubsan h109s standard version, where you can control two axis gimbal by knobs T1 and T2 - but these knobs have nothing to do with h501s.
Both 109s and 501s have A7015 XL.

I suppose that we can be able to use additional channel for gimbal control in 501s - but don`t have so much knowledge which is needed to solve this conundrum. Probably it is needed to modify code of 501s firmware, and add some parts of code from h109s... Secondly probably there is needed to make some additional cable outputs for signals for gimbal driver control (don`t know where...)

Maby you guys have any idea what could I do? Maby somebody is able to give any advice? I really understand that my knowledge is poor about this topic, but i am opened to learn a lot, but need some advice.
It is important for me make very light gimbal for 501s, because 109s is too heavy for free flying in my country,

Cheers

I'm triying to do the same with walkera gimbal 2D.

My first step is to see on hubsan TX what gimbal camera sees. In this video i explain how, is in Spanish



First install a 5,8 ghz fpv transmiter . Dron always OFF
Second, change on Professional TX the video channel receiver to the same channel of fpv tx.
Third,conect gimbal and 5,8 gz tx to the same battery
ourth, tx will tne camera gimbal frequency and you can turn on dron, and you will see gimbal camera on hubsan tx.

.Next step binding Tx to gimbal
Here s where i stay wiht some dudes..
Issues : need to buy a 2,4 receiver , which one? how many channels need, only aux or more?
How to bind hubsan TX to dron and gimbal at the same tine? protocoll, what channels use hubsan tx for 109S o for gimbal??