[OpenWrt-Devel] [PATCH] ar71xx: add support for the UniFi AP Outdoor Plus

Stefan Rompf stefan at loplof.de
Tue Mar 17 16:15:17 EDT 2015

Hi Sergey,

> If they built SPIoverGPIO or I2CoverGPIO or some other serial bus over
> GPIO, then you do not see any changes between channel switches. Or
> they could use some non GPIO interface to communicate with external
> filter (embedded SPI, I2C or even USB or PCI of SoC).

well, GPIO has been the starting point, but it does not seem to be that easy 
;-) Neither GPIO pins of the CPU nor the wifi chip change their static values 
based on the channel. I haven't yet compiled a tool to poll these memory 
locations fast enough to detect a protocol.

> Possibly, you could see some changes during change. Try check GPIO
> pins with oscillograph during channel change.

Unfortunately opening the case is not an option.

> Or you could put device in continuous scan (e.g. use STA mode and
> enter some not available SSID to put device for infinite AP search)

Interesting enough: When stopping all wifi related software on the device and 
creating a monitor interface, the RF filter seems to follow "iwconfig channel" 
commands (yes it is the madwifi driver). So the magic happens in iwconfig or 
the driver, not in some userspace daemon.

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