Question: Redmi Router AC2100 USB Mod

Is there any way to add usb to redmi ac2100 because mt7621 support it?

i've seen this thread

but i have different types of router and cpu

how can i find d+ and d- in motherboard? since those object are not written in the board

or is there any way to add pcie support in this board? since the log mention pcie in it

Check the datasheet of the MT7621. It's a BGA chip, so most of the pins are underneath the chip. However, D- is near the edge of the chip, so it's maybe possible to identify it. With a bit of luck, D- and D+ are brought out to some via or resistor or whatever, similar to the device you linked to.

I was about to do look for the USB pins on the ZyXEL WSM20, but after doing this research, I decided that it's not worth the hassle.

underneath means, in the flip side of the board?

No, on the underside of the chip! There are no solder legs but small balls that need to be heated in an oven. No way to access them if the manufacturer hasn't brought them out to some pad or resistor.

Hello, best way is to get a hold of broken router same hardware version usualy its just couple euros or free. Use hot air soldier station to remove chip. Then use tracking instrument to find is there a surface occurance of mentioned pad. If there is enable it on hardvare description file in compiling.
While at it do some more job and find pci traces and more pads of interest and post back findings.

PS. Tracking tool is that i soldiered on hand held isolated pins on transmiter and reciever. Just conect transmiter on pad and hover ower board with reciever. When i hear tone i just touch close pads on board surface to determine strongest tone and after that check with multimeter for continuity. 9 out 10 times you'll get it on first try.

Best regards.

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hello there, finally got some help from author who make usb mod

i want to ask, if i want to enable ohci and ehci (after doing usb mod)
do i need to compile andflash the firmware?
or simple editing on the file will do just fine? *since i already have a lot of customization on the router, and flashing it will remove all my settings...

In that matter you must compile it from ground up. Kernel must be compiled with usb support. But before all, check the hardware description file in openwrt git clone localy, maybe hardware usb is already enabled and need only to install drivers. I had cases when usb hardware is enabled and all that had to be done is to install uhci, ahci or ehci drivers and all work ok.
Fast check would be to install all usb host control interface drivers and usbutils. Notice some of this will faill because you dont have it all on your hardware.

opkg update
opkg install kmod-usb-core
insmod usbcore
opkg install kmod-usb-uhci
insmod uhci_hcd
opkg install kmod-usb-ohci
insmod ohci
opkg install kmod-usb2
insmod ehci-hcd
opkg install kmod-usb3
insmod xhci-hcd
opkg install kmod-usb-ohci-pci
opkg install kmod-usb2-pci
opkg install usbutils

And just do "lsusb" command. If get error or 99 response or similar without description on usb host controler then u have kernel without usb support.

Best regards

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thanks a lot for this valuable information, never done this before... and i think i need a lot of information before doing this...

by the way i plan to add this 4g cat16 module on my router (by using this usb mod)

is the power from usb enough to power this unit?
i plan to put this inside the redmi ac2100 router, since i think there's plenty of space there

or is it safer to me to use module like this? i think it use jst connector instead of usb

also, i try to read the pdf, and find out there is 2 connector in this chip

M4&M5 = USB Data (+) and Data (-) for USB 3.0
K1&K2 = USB Data (+) and Data (-) for USB 2.0

i try to read some information regarding usb, and it says usb 3.0 might cause interference with 2.4ghz wifi
is it safer for me to use usb 2.0 pin (k1&k2)? or i can use 3.0 pin (m4&m5) with usb 2.0 connector?

You have a bit conundrum on your hand that only can be resolved empirically.

1st u had to have external power supply for that device. Just aperance of heatsink on some device tells you that is powerhungry.

2nd yes 2.4GHz devices sometimes have problems with usb 3.

3rd speed of rf comunication equipement of any kind depends on speed of usb port and host that process that information. Do not expect that 1Gbit device have speed of 1Gbit if speed of usb 2 port is 480 Mbit (bottleneck), allso if have usb 3 speed, does host of device have raw proccessing power to process and releay the packets.

Hello everyone, have a great afternoon! I would like to know if it is possible to obtain the USB MOD for the Xiaomi Mi 4A Gigabit V2, I left a photo of the hardware below. I was looking at the usb mod post and realized that the hardware was totally different.

i see...
so in short, i just connnect D+ and D- pin near cpu
and the other two cables (ground), is from external power source

do i need any capacitor for this mod? (since i don't use internal power source)

i think we have almost same cpu on router (MT7621)
have you tried other mod as well? so far i've tried adding 512mb ram to router and success (don't need any modification on software)

as for usb mod, just like @nikola.kojovic says... you need to remove the cpu first (MT7621), and use tracking instrument to find the usb pin (either usb 2.0 or usb 3.0)

Just a bit digress, and confirmation. That 512MB mod, it worked out of box? Just slap on memmory on a board and it see AND USE propper size of new memmory?
If that true im confused a bit, i missed something in changelogs on updates of kernel trough OpenWRT versions...

Can u post link for that mod pls. Or send me in PM.

i read some comments on this thread

and find this comment (he doesnt post any pic of this mod), i just do it based on his guide (preparing ram from android tv box), and put the 512mb ram into redmi ac2100, it detect new ram automatically without any configuration...

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You need to use appropriate bootloader and RAM chip.

I have tested that using BREED will indeed automatically detect your RAM (128, 256 or 512 MB for mt7621, or 128 and 256 MB for mt7620). Use appropriate one for your board, for example r3g for NAND, and pbr-m1 for SPI NOR. But beware, the newest release (r1416) is unbootable on redmi ac2100 and R3P.

You can also try compiling your own u-boot for mt7621 from this github repo.

OpenWrt will automatically detect your RAM.

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I have installed Padavan on the Redmi ac2100; I plan to make the usb mod to be able to enable the Transmission client. Can you please give me detailed information about how to do the usb mod ? Thank you in advance

Many low-end 7621 router with USB port, no need to mod/add for this.

Xiaomi Mi Router 3 Pro (R3P)
Xiaomi Mi WiFi R3G (Mi Wifi Router 3G / MIR3G / MI3G)
Xiaomi 3 (MIR3, USB2.0)

very lower cost in 2nd hands....