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Airlink101 AR725W

Supported Versions

Version/Model Launch Date S/N OpenWrt Version Supported Model Specific Notes
v1 - 14.07 -

Hardware Highlights

CPU Ram Flash Network USB Serial JTag
Ralink RT2880 32MiB 4MiB 5 x 100Mbit No Yes ?


The SoC's builtin Ethernet is connected to a IP175E 5-port 100mbit switch. VLAN setup is supported in OpenWRT.

Serial Port

The serial port is located at J6 on the board. The baud rate is 57600.

TXD 0 0 VCC 3.3V
    0 0 VCC 3.3V
    0 0 GND


The factory firmware expects a header, apparently proprietary to routers based on Gemtek boards.

/* Gemtek */
typedef struct {
        unsigned char   magic[4];       /* ASCII: GMTK */
        unsigned char   version[4];     /* x.x.x.x */
        unsigned int    pid;            /* Product ID */
        unsigned int    imagesz;        /* The length of this image file ( kernel +
                                         * romfs + this header) */
        unsigned int    checksum;       /* CRC32 */
        unsigned int    fastcksum;      /* Partial CRC32 on (First(256),
                                         * medium(256), last(512)) */
        unsigned char   build[4];
        unsigned char   language[4];
} gt_imghdr_t;

The program mkheader_gemtek, part of firmware-utils, generates this header from a uImage. The header is not written to flash.

Default layout

The bootloader is uBoot.

Mapped starting at 0xbc400000:

0x000000 - 0x050000 uBoot
    0x30000 uBoot environment variables
    0x40000 RT2872 EEPROM data
    0x40004 MAC address

0x050000 - 0x130000 Linux Kernel
0x130000 - 0x390000 RootFS
0x390000 - 0x3e0000 LANGUAGE_PACK
0x3e0000 - 0x3f0000 NVRAM
0x3f0000 - 0x400000 NVRAM_FACTORY

Since the language and NVRAM partitions are only used by the factory firmware, OpenWRT uses a single partition starting at 0x50000 and running to the end of the 4MB.

toh/airlink101/ar725w.txt · Last modified: 2014/12/06 14:16 by leitec