Computer Nerd Kev  wrote:
> It also has a built-in broadcast FM radio receiver, controlled via
> the same UART interface as the Bluetooth controller. This is able to
> output analogue stereo audio, or provide a digital stream. Most
> likely the pin that the FM antenna needs to be connected to isn't
> connected on the Pi circuit board, though you never know maybe it
> goes to one of the undocumented test pads?

Nice idea.  The pin is pad E1 which is actually on one edge of the chip.
Here's a picture:

https://i.stack.imgur.com/EuIHC.jpg

The orientation is unclear from that photo but it looks like pin A1 is the
bottom left, and the small capacitor to the right of the writing 'C252' is
connected to F1 and G1.  I can't see what E1 does from behind it, and
whether something could get at the ball from the side, or whether it's
grounded.

You can always try bonding an antenna to the PCB anyway, and relying on
capacitive coupling ;-)

> The commands for controlling it over the UART connection are probably
> documented in Cypress' WICED SDK package.
> https://community.cypress.com/message/179340

It's likely Android sources include it too, since FM using the wifi chip is
common on phones.

Theo

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