Main board Chips 1xEM8621-Rev.C 1x K8D6316UTM-PI07 2x HY5DU561622DT-5 1x WM8728S 1x PL-2507 1x VT6212L 1x RTL8100B or RTL8100CL (depending on board revision) 1 x RT2561ST Memory map of the MG-350HD ROM/RAM remapping Serial header J2 USB interface External IR receiver

 

Main board

 

The heart of this board is the Sigma Designs EM8621, a digital media processor incorporating a 166MHz ARM CPU, an integrated IDE controller, and the audio and video decoders.

 

The CPU info, as in /proc/cpuinfo is:

Processor : ARM pt110 rev 0 (v4l)

BogoMIPS : 82.94

Hardware : EM86XX

Revision : 0000

Serial : 0000000000000000

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Chips

Note that some devices may be different to your MG-350HD, particularly flash and SDRAM, but it's roughly this.

 

1xEM8621-Rev.C

Sigma Dev = Digital media processor with MPEG-4.10 (H.264), SMPTE 421M (VC-1), WMV9, MPEG-4.2 and MPEG-2 decoding. This is equivalent to a 200MHz pt110 (a clone of the ARM7) processor with no MMU.

 

1x K8D6316UTM-PI07

Samsung = 64Mb dual bank NOR flash memory (that's 64 megabit, not 64 megabyte!)

 

2x HY5DU561622DT-5

Hynix = 256Mb DDR SDRAM

 

1x WM8728S

Wolfson = 192kHz Stereo DAC.

 

1x PL-2507

Prolific = USB2.0 to IDE bridge controller.

Functional description here

 

1x VT6212L

VIA = PCI USB 2.0 4-port host controller

 

1x RTL8100B or RTL8100CL (depending on board revision)

Realtek = single chip 10/100 Mbps ethernet controller with power management

 

1 x RT2561ST

Ralink 802.11a/b/g WiFi chip on a MiniPCI card

 

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Memory map of the MG-350HD

 

 

Here is the content of /proc/iomem file:

 

0006c100-0006c13f : serial_em86xx
60100000-6010ffff : PCI device 10ec:8139
60110000-601100ff : PCI device 10ec:8139
  60110000-601100ff : 8139too
60110100-601101ff : PCI device 1106:3104
  60110100-601101ff : ehci_hcd
90090000-91f8ffff : System RAM
  900b3000-9023e7bf : Kernel code
  9023e7c0-902a333f : Kernel data

 In addition, from the bootloader messages we know that config data is apparently stored beginning at 0x90080000, and that flash is mapped to 0x46000000 - 0x46800000

 

 

ROM/RAM remapping

 

Using this as a peek

./busybox dd if=/dev/mem of=b8191.0 bs=1 skip=8191 count=2

 

and this as a poke

./busybox dd if=/dev/zero of=/dev/mem bs=1 seek=8191 count=2

 

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Serial header J2

We can connect a RS232 level converter to this header, to have console access. This is important to de-brick a dead device, but only if the flash bootloader is still intact.

 

These are the voltages on the header (pin 1 is the one with the silk screen arrow on the top):

 

 

2  4  6  8  10
1  3  5  7  9
            J2

1 - TxD from board
3 - 3.3V VCC
5 - RxD to bard
7 - Gnd

 

A good converter to use is the one found here. It costs from about $10.00 USD (bare board) to about $25.00 USD (assembled and tested). The one offered comes with a max232 chip that needs a 5V supply, and since the MB connector only provides 3.3V, you will want to populate the board with a MAX3232E IC since it operates at both 5V and 3.3V.

 

Maxim makes a number of MAX3232E chips, in various packages. If you want to swap the chip on the above board, the MAX3232ECPE is a 16-pin through-hole package similar to that shown on the page for the RS-1 above. If you can't get that one, a MAX3232ECAE would work, but it's surface-mount and so the soldering is a little more tricky.

 

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USB interface

The USB interface has direct access to the HDD, without passing through the firmware. We suspect the Prolific USB->IDE chip is wired directly onto the IDE bus and acts as sole master when USB is connected. It probably holds the EM8621 in reset at this time.

 

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External IR receiver

See MG35Hardware ExternalIRreceiver .

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