Bluetooth

Bluetooth
Status	In Development
menuconfig	I/O->Radio->Bluetooth
Pinning	yes
Ecmd	yes
Control6	-
Uses Timer	-
Depends on	-
Requires	Free UART
Code	https://github.com/ethersex/ethersex/tree/master/hardware/radio/bluetooth

BT0417C is a generic Bluetooth module loaded with SPP firmware for UART wireless cable replacement functions. It allows your target device to both send or receive the TTL data via Bluetooth technology without connecting a serial cable to your computer.

Features:

• TTL data transparent transfer between a host Bluetooth device
• Compatible with all Bluetooth adapters that support SPP
• Default baud rate: 9600,8,1,N
• Pair code: 1234
• Built in antenna
• Bluetooth Technology v2.0 compatible
• Power input:3.3VDC
• Compact Size

Connection

When used with 5V microcontrollers, the TXD output logic swing of the module still falls within the valid 5V TTL range, hence, can be connected directly to the UART RXD of the 5V microcontroller host. The RXD and inputs, however, are not 5V tolerant, and can be damaged by 5V level logic going in. Some level translation circuit must be added to protect the inputs. A simple diode level translator circuit like the ones shown in Figure 2 will suffice in most applications. A better alternative is with the use of 5V input tolerant tiny logic chips such as 74LVC1G125 – a single buffer chip housed in SMD SOT23-5 package.

• 

  BT0417C and breakout board

• 

  BT0417C to MCU (5V)

• 

  BT0417C to MCU (3,3V)

Attention: there are different version of the module and breakout board around with different firmware and pin assignment.

The module is connected to a free USART (TX/RX). In addition it requires at least an free I/O pin.

 /* switch between data and command mode (mandatory) */
 pin(BT_MODULE_KEY,   PC1, OUTPUT)
 /* read back pairing state of module (optional) */
 pin(BT_MODULE_STATE, PC3, INPUT)

Configuration

The base configuration of the module:

 | |                        I/O  --->                                                        | |
 ...
 | |                  Radio  --->                                                            | |
 | |                               [ ] FS20 RF-control  --->                                 | |
 | |                               [ ] RFM12 ASK  --->                                       | |
 | |                               [ ] Generic ASK (433MHz)                                  | |
 | |                               [*] Bluetooth  --->                                       | |
 ...
 | |                             (3)   Bluetooth usart select                                | |
 | |                             (115200) USART Baudrate                                     | |
 | |                                  Device Name: "ethersex"                                | |
 | |                                  Device PIN: "1234"                                     | |
 | |                             --- ECMD                                                    | |
 | |                             [ ] AT Command Interface                                    | |
 | |                             --- Debugging Flags                                         | |
 | |                             [ ] Bluetooth                                               | |

Optionally the module can be used with ECMD:

 | |                        Protocols  --->                                                  | |
 ... 
 | |              [*] ECMD (Ethersex Command) support  --->                                  | |
 ...
 | |                       --- ECMD interfaces                                               | |
 ...
 | |                       [-] USB                                                           | |
 | |                       [*] Bluetooth                                                     | |

Links

Serial Bluetooth RF Transceiver Module RS232
Firmware programmer
Martyn Currey's Blog
AT Command Mode of HC-05 and HC-06 Bluetooth Module