Repurposing Gramofon FON2415

Hardware Questions and Recommendations
1

Hi all,

I've been working on repurposing a Gramofon FON2415 (also known as FON2515A02),
a discontinued cloud music streamer from Fon Wireless. The cloud infrastructure
has been dead for years, so I'd like to run OpenWrt on it to use the hardware
as an audio streaming device. With help from Claude Code, I would not have started this endeavour without it (I looked for ways of flashing it in the past, but never got where I am now: working OpenWRT, but no sound).

I've successfully gained UART access and have a root shell via U-Boot.
Here's what I know about the hardware:

Hardware specs:

  • CPU: Atheros AR9341 (535MHz MIPS 74Kc)
  • RAM: ESMT M14D5121632A — 64MB DDR2
  • Flash: MXIC MX25L128 — 16MB
  • WiFi: 2.4GHz 802.11b/g/n (built into AR9341)
  • Audio: AKM AK4430ET DAC (3.5mm jack output)
  • Ethernet: 2x ports (WAN + LAN)
  • Board name: "Fonera HUB FON2415 board" (from kernel log)

U-Boot environment (printenv):

bootargs=
bootcmd=bootm 0x9f020000
bootdelay=1
baudrate=115200
ipaddr=192.168.10.1
serverip=192.168.10.100
lu=tftp 0x80060000 fon2415.uboot; erase 0x9f000000 +$filesize; cp.b $fileaddr 0x9f000000 $filesize
lf=tftp 0x80060000 fon2415.image; erase 0x9f020000 +$filesize; cp.b $fileaddr 0x9f020000 $filesize

Flash layout (/proc/mtd):
mtd0: 00020000 00010000 "u-boot"        (128KB)
mtd1: 00fc0000 00010000 "firmware"      (15.75MB)
mtd2: 00ec6684 00010000 "rootfs"
mtd3: 00680000 00010000 "rootfs_data"
mtd4: 00010000 00010000 "fon_data"
mtd5: 00010000 00010000 "art"           (WiFi calibration)

UART: J2 header on PCB, 115200 8N1, 3.3V TTL
U-Boot TFTP flash command: run lf (expects file "fon2415.image" from TFTP server)

The current firmware is a very old OpenWrt-based Fon build
(kernel ~3.x, BusyBox 1.19.4, built 2015).
The filesystem is squashfs (read-only) with jffs2 overlay.

My questions:

  1. Is there an existing OpenWrt profile for this device or something close
    (same AR9341 + 16MB flash layout)?
  2. What would be the correct ath79 DTS to use as a starting point?
  3. The U-Boot lf command flashes starting at 0x9f020000 — is a standard
    OpenWrt factory image compatible with this, or does it need a specific header?

Happy to provide more details or test images.
Thanks!

2

https://openwrt.org/supported_devices/864_warning, sure you want to pour your free time into this ?

3

Ah, maybe not... In that case I am just wondering if ever anyone tried to repurpose the device, but probably not.
Thanks for pointing it out!

4

it's a great sand box if you want to learn how to add support for other devices, if you only want to do this one, not so much.

5

I would of course publish it somewhere! I have 3 of those little devices and they are useless as I stopped using Spotify and the TuneIn version is so old it only works with a very old OnePlusX as there is no way of connecting to the box otherwise.

6

I can def see a purpose for them, but it also depends on use case.
they would last longer if wifi wasn't required for whatever you'd like to use them for.

7

I want to use them as audio devices. I use ethernet for some of them, others wifi. But I don't use it as a wifi extender (Which was one of the purposes of the devices back in the day)

8

the audio part is probably doable if the DAC's supported, etc.

9

I guess the difficult part is to get the sound output to work with the current linux kernel. There used to be some interest in a similar device quite a while ago (see link below). Someone managed to get OpenWrt working but only on a specific kernel version due to the available source of the audio drivers.

10

Yeah, it seems so. Thanks for the links! Very useful.

11

64 MB RAM is quite limiting, but I guess you'd still manage to get it merged at this point (but maybe not 1-2 years further into the future).

12

the initramfs of the OMYlink OMY-X1 might boot for you if you have serial and tftp available.