I copied this from [1] and I don't know the rights owner. I will ask Albert.

BC2MOD2C is a CSR name. Seeing it on the module probably means that the manufacturer has copied our reference design. This is a good thing - we put a lot of time and effort into our reference designs, we're only too happy if manufacturers copy them exactly.

It's not clear whether they'll have copied just our schematic, or the whole board layout. We encourage manufacturers to copy the layout exactly. This is because the RF routing is quite tricky and very sensitive to changes. Even if they copied the layout, they may have chosen to omit lines they weren't using (such as UART).

If you're lucky, they'll just have copied they whole thing verbatim. We provide manufacturers with all the information they need to make it easy for them. If they've copied the layout, it will look something like this (ASCII art picture follows):

     |<---14.70 mm -->|
   - +----------------+
   ^ ++-----------+=..|
   | ||   Flash   |[#]|
   | ||           |' '|
   2 |+-----------+...|
   5 |'+----------+'++|
   . |,|          | ++|
   0 | |   BC02   |=: |
   0 |'|          |-. |
     |,|          |+-+|
   m | +----------+| ||
   m | '(.),'' +-+|
   | | . . . ++  ,   -|
   | | +--+  ++' ' '++|
   v | +--+    -    ++|
   - +----------------+ 1
     ^^^^^^^ Will be marked BC2MOD2C here.

If it does, then the pinout is (viewed from above, in the orientation shown):

18                   17
 PCM_OUT        GROUND
 PCM_SYNC          3V3
 PCM_IN            1V8
 PCM_CLK       UART_RX
 USB_DP       UART_RTS
 USB_DN        UART_TX
 PIO(7)       UART_CTS
 PIO(6)         ignore
 PIO(5)         ignore
 PIO(4)         ignore
 PIO(3)         ignore
 PIO(2)          RESET
 PIO(1)         AIO(1)
 PIO(0)         AIO(0)
 GROUND         GROUND
 RF         NO CONNECT
 GROUND         GROUND
34                    1

Pins 32 and 34 are the RF signal ground, whereas pins 1, 3 and 17 are just normal grounds. When connecting to an antenna, it's the RF ground you need to use.

If the flash needs 3.3 V then you need to connect just the 3V3 supply on pin 16 and an internal voltage regulator will supply the 1.8 V for BlueCore and will output 1.8 V on pin 15. If the flash is running off 1.8 V then I think you can run the same way, or you can supply 1.8 V on pin 15. If I read the schematic correctly, then supplying both of 1.8 V and 3.3 V at the same time would be a bad idea.

You need to pay close attention to the power up sequence. The flash supply needs to be stable before the BlueCore is allowed to boot. If the flash is running at 3.3 V then I think that the BC2MOD2C design contains the appropriate circuitry to delay the powering up of the 1.8 V supply. You can check this by monitoring pin 15 with a scope while applying power to pin 16. If the flash is running at 1.8 V, then you'll need to hold the BlueCore in reset until the flash is running. You can find out more about power up sequencing by reading BlueCore2-External Power-Up Sequence (bc2x-an-001Pa) on the CSR support web site. You'll need to register to get access to that document, but it should be available at the basic access level.

You'll need to supply an antenna. Antenna design is deep black magic. Since the UART and USB pins are separate on the module, you may be able to keep it soldered onto the module to keep access to the existing antenna and just solder on some flying leads to get to the UART. Strictly speaking, antenna performance is affected even by the presence of plastic nearby. There can be a noticeable change in the RF performance of a module when you put it into a new housing. For a hobby project, you'll probably get away with it, but for a commercial design, you'd need to requalify.