CSR8645 bluetooth module pins

[reynard80]

I just received a CSR8645 bluetooth module from China. It does contain some pinholes that I can't figure out what they are for (not even with the datasheet).

It's the module in the attachment, and I mean the IKBOEVG pin holes. Only thing I can think of is that they are serial pins?

[Buriedcode]

I have that bluetooth module (blue CSR8645, with EEPROM) - but on a different breakout board, where all pins are broken out, and there is only minimal circuitry on board (power-on enable, and mic input paossives).

As thats a nice big image of it I think I can name the pins from where they are connected on that module - the blue board, not the carrier. 

If we number the pins from the top left, down, across the bottom, then up the right...
1 = optional antenna, NC.
2 = LED1
3 = LED0
4 = AI0, NC
5 = SPI_MISO
6 = SPI_CS
7 = SPI_CLK
8 = SPI_MOSI
9 = SPI/PCM. - note I2S/PCM is most likely disabled on the ROM, so this pin must be high to enable the SPI port for configuration.

It seems the smaller half pitch holes are indeed for the SPI connection.  One would need 7 pins... two for power and ground, 4 for the SPI port, and one to enable the SPI port.  I am guessing this is just a config header for use with CSR's USB adapter (there's an open source one that just uses an FT232R, google "csr-spi-ftdi").

As for the naming, you'll have to check which pins are connected to the module
K is connected to pin 6, which is SPI_CS.
E is connected to pin 9, which is SPI/PCM, should be pulled high to IO voltage (1.8V on this module, but you can get away wtih 3.3V via a 10k resistor).
I'm guessing 'I' is input, as this is a slave device, that would me MOSI.
Also guessing 'O' is output.. MISO.
That leaves 'B, which might be clock.  Note these are guesses.

As I said you'll have to check with a continuity tester.

Link to pinout of the actual module: http://www.electrodragon.com/w/File:8645_pin_definition.png

[reynard80]

Thanks, that's a nice and clear reply!

I'll try to use the SPI. Still one question though; regular pin headers won't fit into those pin holes, obviously. What would be the best way to connect to those pins with the small holes?

[Buriedcode]

Well, there are half-pitch  (0.05"/1.27mm) headers available, and whilst that's neat, it doesn't really help as it just moves the problem to... using a half pitch socket.. with wires soldered to it.  So I would just solder individual wires to the holes, then these to a standard 0.1" header. 

For a semi 'neat' way, use ribbon cable with a 10-way IDC header on the other end. https://cdn-shop.adafruit.com/1200x900/556-00.jpg  IDC ribbon cable naturally has a pitch of 1.27mm, but i always found it a sod to solder onto boards with the same pitch.

Both the above will have no strain relief on the wires, and so, will happily break off after moving them about lots.  I think JST and molex to shrouded pin headers, cable-board connectors like this:

http://www.elechouse.com/elechouse/images/large/product/1.27mm10p_LRG.jpg

If you are planning on constantly plugging and unplug wires to the board for config. But for just fiddling about, changing the bluetooth modules name, and parameters a few times, wires -> header would be easiest.

[reynard80]

Thanks all,

After some continuity testing I got the following results:

I MOSI
K CLK
B CSB
O MISO
E SPI-PCM
V 3V3
G GND

I think I'll opt for some neat JST connector while I am waiting for my FT232RL to arrive. Let's see if it'll be possible to play a bit with the module.