Sercomm NA502

The Sercomm NA502 is a ZigBee/Z-Wave gateway sold under various brands (e.g. A1 Smart Home Gateway in Austria). It is based on the MediaTek MT7621 SoC with a Gigabit Ethernet port.

Important Some variants, like the Vera gateway, seem to have a crippled U-Boot that don't allow loading code to SDRAM via TFTP. So far, no solution exists for those gateways.

Important: You need to attach a serial console to the unpopulated PIN header on the main PCB in order to install OpenWrt from U-Boot. There is a recovery mode, but the image format is currently unknown!

You need to attach a serial console to the unpopulated 4-pin header near the LEDs. With the front of the device facing towards you, the pinout is: GND - TXD - ? - RXD. The settings are 57600 8N1 and you should see a bunch of messages immediately after start.

• Using the terminal, select option 1. Load system code to SDRAM via TFTP.
• Put the initramfs OpenWrt image on your TFTP server and boot it.
• You can then use SSH to connect to the OpenWrt running from RAM.
• Transfer the OpenWrt squashfs image to the device (for instance to /tmp/openwrt.bin)
• Run sysupgrade -n /tmp/openwrt.bin to install the image to your device.

The device contains a recovery image in the first partition. If the device is brand new, connect it to the Internet so that it auto-updates the second image. Afterwards, the device boots always from image 2 as longs as its checksum is correct.

If you don't install a valid OEM firmware to image 2 first, the auto-update stored in image 1 overwrites OpenWrt right away.

There are Z-Wave and ZigBee modules. Both can be exposed using ser2net so that another gateway solution can connect to it.

• The Z-Wave module is at /dev/ttyS1 with 115200 8N1
• The ZigBee modules is at /dev/ttyS2 with 57600 8N1

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