sermon

Serial communication with a SIM808 GPRS module via usb-ttl adapater

Introduction

sermon is a light-weight curses-based terminal serial monitor used for reading and writing to serial devices during embedded development sessions. The sermon text interface uses vim inspired key bindings to switch between insert mode and command mode.

Command line usage allows optional specification of three arguments, namely the device port to open a serial connection on, the terminating character to send after submitting input to the serial device, and the baud rate.

Dependencies

sermon makes use of the serial module, installable via the pyserial Pip package. Install using the requirements.txt file

sudo pip3 install -r requirements.txt

Usage

./sermon [ -p ] [ PORT ] [ -t ] [ TERMINATION CHAR ] [ -b ] [ BAUD RATE ]

Port

Without arguments sermon isn't very useful. At minimum a serial device should be specified with the -p argument. The following opens a serial session on /dev/USB0

./sermon -p /dev/USB0

Termination Character

Some serial enabled devices are picky about what constitutes a complete transmission. When sending messages to a serial device with sermon, the default behavior is to append a \n character to the message.

However this can be changed by specifying the -t argument with the the following options.

• nl -> Newline/line feed \n

• cr -> Carriage return \r

• nlcr -> Newline/linefeed + Carriage return \r\n

The following opens a serial session on /dev/USB0, and specifies the termination sequence as \n\r

./sermon  -p /dev/USB0 -t nlcr

Baud Rate

sermon also allows you to set the baud rate for the serial communication session with the -b flag. This option defaults to 9600 if no baud rate is specified.

Runtime Command Modes

To begin entering commands, enter command mode using the ESC key and then open the command buffer by typing the character ':'

Port

In command mode you can specify on the fly the serial port to read/write from by using the 'port' command.

• Usage: :port [ PORT ]
• Example: :port /dev/ttyACM0

Raw Byte Transmission

In addition to entering ASCII range input, you can also write raw bytes directly to the device by using the 'byte' command.

• Usage: :byte [ BYTE INTEGER VALUE ]
  
• Example: :byte 26 ( sends CTRL-Z )

Contact

sermon is slowly being revived as I continue with my own embedded projects. The latest release, v1.1, fixes a handful of annoying bugs that were present in the previous iterations. To report a bug, please open an issue at https://github.com/xdmtk/sermon/issues , though I may not get around to it.