Opening up my router Tenda fh305

OK, In January 2018, I hv opened up my router to see and understand what it has.  Also downloaded the  schematic Diagram  through a source from tenda china.  To my surprise, I have found out that they are producing routers with same hardware, changing here and there and the router outer shell/box.  My last router was the same of this one but with a bit powerful  wifi amplifier. But this amp. needed a good antenna which the router lacked. It is a Tenda fh305.  

Most routers of 2014/15 they had e-cos os that they cram them into a 2 mb flash chip.  Also they used a 16 Mega Byte ddr ram chip, which is really low even for the features e-cos had!!

So, as a result after few minutes of routing...the router started to falter, Wifi restarts driver automatically as NAT stuff required more ram then it got.

I started to look for other routers.  Usually high end routers are very expensive in my country due to high tax policy . If it cost $90 in china/elsewhere it becomes $200 here in bangladesh.  Then started to look into asus and tp-link routers, low end tp-links are still cheaper but better and more expensive then tenda routers!!. Please note I have bought this router with same or higher price then tp-link standard router,  as it's suppose to be better, but not really!!

Asus and tenda was using Linux and looks similar to pc linux os'es.  

I wanted to see how all these routers were booting, that u can never see from the web interface!!

So, I hv figured, most routers including tenda's got serial interface that is built into the SoC.  I can see this in the diagram I received(Cannot post, sorry). This is needed for the router company engineers to debug their routers and develop software!!

So, this is my chance.  I have bought a USB to Serial TTL Converter cp2102 and also bought a cheap programmer, which is also a Serial converter, very popular in china and the rest of the world.  It's CH341A.

You can buy this off of Ali Express for $2.20(Ch341a). But the cp2102 is available in my local tech shop for also similar price.

So, One day got the cp2102 and some wires and connector pins to connect to the serial port of the router. Here is the one for my fh305,

If u See the Red Box and the text, This is the Serial Port of my Tenda fh305, This is the Mainboard of a typical router i.e. Tenda fh305.  

Here is also see the 2 Mb Flash chip. Router mainboard got,

1. SOC Aka CPU : BCM5357 COKFBG
It's a 300 Mhz Broadcom cpu for value routers
2. Flash : 2 MB
Giga Device 25Q16BSIG
16 M-bit/ 8 Mbit = 2 MB or 2048 K bytes
3. Ram : 16 MB M13S128168A -5T (200 Mhz)
2M X 16Bit x 4 Banks = 128 Mbit/ 8 Mbit = 16 MB
vdd= 2.375v to 2.75v 66 pin tsop II package

Ram chip Cannot be seen in above image...also It's sitting in the Opposite direction to the flash/soc so here is another image for ram,

Now I know what my router got, so Is there any custom os or firmware for this router??, Is it possible to install any firmware other then the default e-cos??!!

My Search continues....