p.Brain-SMB & Sparkfun BluSmirf Connection

Updated: 30-Dec-2008

This guide will explain how to connect your p.Brain-SMB to a BlueSmirf bluetooth module.

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By Matt Denton & PaulP

Number02 Connection
Number02 Configuration




p.Brain-SMB V1.0

Number02 Connection
2 4 6 8 10
1 3 5 7 9




To implement Bluetooth with a ‘Smirf, firstly ensure that the ESD200 unit is not fitted and None of the jumpers on JP1 are fitted.

All the connections necessary are provided via CN17, the layout of which is shown opposite.

The pins on the ‘Smirf are labeled as follows:

  • CTS
  • PWR
  • GND
  • TX
  • RX
  • RTS

The ‘Smirf does not require flow control so CTS should be linked to RTS.

PWR 5V Supply
GND 0V Supply
TX Data Transmit
RX Data Receive


Number02 Configuration
Baud rate Decimal Hex
1200 5 5
2400 10 A
4800 20 14
9600 39 27
19.2K 79 4F
38.4K 137 9D
57.6K 236 EC
115.2K 472 1D8
230.4K 944 3B0
460.8K 1887 75F
921.6K 3775 EBF

BlueSmirf Baud Rate Table.


Baud Rate CBR value
1200 0
2400 1
4800 2
9600 3
19.2K 4


57.6K 6
115.2K 7

HexEngine Baud Rate Table.


Once connected and powered the Green LED on the ‘Smirf should flash apron 2Hz.

Open a Terminal in either Hyperterm or teraterm and connect as you would normally to the Bluetooth COM port.

The Green LED on the ‘Smirf should go off and the RED led should be on solid. On the terminal application, type:

+++ <CR>

Where <CR> is carriage return or enter key.

You may not see the characters being echoed and you may nor may not see the unit respond with OK. This is dependent upon your current settings for the BlueSmirf.



You may get an OK followed by a response such as:


The first part is the baud rate, the second is the Parity, The third is the Stop bits. The baud rate is returned in Hex but must be set in decimal. The Baud rate values are shown in the table opposite.

In the example above, 01D8 indicates the baud rate is set to 115200. To change the baud rate, use the following format: ATSW20,<Baudrate>,<Parity>,<Stop Bits>,<Store><CR> e.g. Type:


This will set the baud rate between the ‘Smirf and the UART of the p.Brain-HexEngine. This must match the baud rate configuration on the HexEngine (CBR command). It does not effect the baud rate between the P.C. and the Bluetooth dongle/device on the P.C.

In order to configure the CBR baud rate on the HexEngine, connect to the HexEngine via the terminal port using a p.Brain-RJ232 lead, open a terminal screen such as Hyperterm or terraterm. Power up the HexEngine, go to the CONFIG menu and type: CBR=X where X= your desired baud rate, see table opposite. For further details on the CBR setting please consult the HexEngine user guide.

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