Converting Upgrades for TEW-673GRU or Dir-825 B1 Into WNDR 3800

For Developers
1

this is more of a FYI of what can be done for hardware upgrades,

I was able to successfully convert a DIR 825 B1 into WNDR 3800 mainly from information from sakatgg https://forum.ixbt.com/topic.cgi?id=14:53410-11 Latest build ( OpenWrt 19.07.7, r11306-c4a6851c72) as of May 3/2021

Highlights:
RAM ( 64MB to 128MB)
Flash (8MB to 16MB),

Reason it works is the WNDR 3800 uses the same hardware as TEW-673GRU and DIR 825, it should also possible to upgrade to 128MB flash although I do not have the chip to try it at time of writing.

All devices use: Atheros AR7161 with radio chips: Atheros AR9220, Atheros AR9223

FLASH: FL128 spansion 16MB NOR (S25FL128 or any 16MB spansion))
RAM: HY5DU121622DTP-D43-C, I also tried the H5DU5162ETR-E3C ( but didnt work not sure if it was a contact issue or the chip was incompatible)

This is not an easy or simple MOD, you have been advised. Easy to destroy your board
You can follow the forum links for instructions to carry out the firmware portion of the Mod.

In my Example the router ( DIR-825 B1) is effectively converted into: (WNDR3800)

2636×3900

2520×4012 

BusyBox v1.30.1 () built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt 19.07.7, r11306-c4a6851c72
 -----------------------------------------------------
# cat /proc/cpuinfo
system type		: Atheros AR7161 rev 2
machine			: NETGEAR WNDR3700/WNDR3800/WNDRMAC
processor		: 0
cpu model		: MIPS 24Kc V7.4
BogoMIPS		: 452.19
wait instruction	: yes
microsecond timers	: yes
tlb_entries		: 16
extra interrupt vector	: yes
hardware watchpoint	: yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa			: mips1 mips2 mips32r1 mips32r2
ASEs implemented	: mips16
Options implemented	: tlb 4kex 4k_cache prefetch mcheck ejtag llsc dc_aliases perf_cntr_intr_bit nan_legacy nan_2008 perf
shadow register sets	: 1
kscratch registers	: 0
package			: 0
core			: 0
VCED exceptions		: not available
VCEI exceptions		: not available

Partition Map:
dev: size erasesize name
mtd0: 00050000 00010000 "u-boot"
mtd1: 00020000 00010000 "u-boot-env"
mtd2: 00f80000 00010000 "firmware"
mtd3: 00189440 00010000 "kernel"
mtd4: 00df6bc0 00010000 "rootfs"
mtd5: 00b80000 00010000 "rootfs_data"
mtd6: 00010000 00010000 "art"

Memory:
total used free shared buff/cache available
Mem: 124612 16816 95668 264 12128 77920
Swap: 0 0 0

2

No, you haven't 'converted' either of those two devices to a WNDR3800, you have just replaced/ extended their flash- and RAM chips. Forcing a WNDR3800 image on these devices, rather than modifying the existing tew-673gru/ dir-825-b1 images to account for the additional flash/ RAM (and ideally adding a special image variant for them) is just wrong, fragile and [CENSORED]. These devices are not the same, they differ in quite serious ways (GPIOs/ LEDs, MAC definitions and everything else relying on the bootloader environment or wireless calibration data, mdio/ switch configuration, and much, much more), not accounted for by the wrong image, doing it this way is both more complex and dangerous (in terms of the process of your 'conversion') and very fragile.

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