blepty

Create a PTY interface for an HM-1x Bluetooth LE module on Linux.

This program makes it possible to use applications which expect to talk to a normal serial port (/dev/ttySx or /dev/ttyACMx) with devices that use HM-1x BLE adapters. It does this by creating a pseudo-terminal (PTY) and forwarding data between the PTY and the BLE adapter.

Prerequisites

1. A Bluetooth LE adapter on the host computer.
2. A Bluetooth LE device using a JNHuaMao BLE modules.
3. A supported OS on the host computer (Linux for now)
4. The necessary Python Bluetooth and GATT suport libraries. (pybluez and gattlib)

Usage

blepty.py connects to a JNHuaMao Bluetooth Low Energy module and creates a pseudo-terminal (pty) that can be opened like a serial port. The program writes the path to the terminal program and then runs in the foreground, passing data between the BLE module and the PTY.

First, find the BLE device you wish to connect to.

$ sudo ./blepty.py -l
Devices
    name: TNC5 BLE, address: 00:0E:0B:03:05:FA

Then, run the program, connecting to the device's MAC address:

$ sudo ./blepty.py -m 00:0E:0B:03:05:FA
Listening on /dev/pts/9
data: 00

Note that it created a PTY here at /dev/pts/9. Any program that can talk to a serial port can connect to the PTY at this path.

Capabilities

This program must be run as root because interpreted programs cannot have capabilities assigned to them. If they could, then

sudo setcap 'cap_net_raw,cap_net_admin+eip' blepty.py 

would allow this program to run without root privileges.

Another work-around is to use cython to compile the program into a standalone executable and then apply the capabilities to that executable.

$ cython --embed blepty.py 
$ make blepty CFLAGS="-I/usr/include/python2.7" LDFLAGS="-lpython2.7"
$ sudo setcap 'cap_net_raw,cap_net_admin+eip' blepty