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[* black] And now, some obligatory close-ups of the circuit board.
[* red] The identity of chip in the center of the board (second photo, in the red square) has eluded me for quite a while. The logo appears to read "CSI" but it actually turns out to be "csr". Given the size and mounting, it's probably a BlueCore4 series (not sure of the exact model).
[* icon_note] This one chip handles pretty much everything. It contains the radio, baseband, and microcontroller. It runs off 1.8V to 3.6V controlled by an integrated voltage regulator. It supports v2.0+ EDR and can coexist with nearby 802.11 (WiFi) networks. It can even work directly with up to 8Mbit flash memory (according to the specifications, given the 8x8mm size of the package (mind out of the gutter please), it's likely external to the chip).
[* blue] There could be something under the board the main chip is mounted on, but I don't have a way to get to it.
- [* yellow] This was a lot easier to identify. It's an antenna.
- [* icon_note] It's a "Fractus Slim Reach Xtend™ Bluetooth Wireless Headset Antenna", designed to also support 802.11b/g/n (basically anything in the 2.4Ghz range). It is tiny, only 7x3x1mm. It's not a particularly efficient antenna (rated at >50% radiation efficiency), but it was probably chosen for size. It's still a good one, I can be on the side of the house opposite of my phone and still have good reception.
- [* black] For only 1mm thicker, Bluetrek could have used the more efficient "Compact Reach Xtend™", with a radiation efficiency rating of >70%.
- [* black] There's a few mentions of Innovi on the board. At the time of this writing, Innovi's website seems to be down. From what I've gathered off of Google, Innovi might be either Bluetrek's old name or their parent company.
+ [* black] There's a few mentions of Innovi on the board. According to LinkedIn, Innovi might be either Bluetrek's old name or their parent company.