On my windows machine I used Putty for this purpose. In mac there is Zterm as an alternative, but I wanted to use the terminal. Screen is the perfect alternative for this job. The workflow is the following:
1. Find out the serial number of your BusPirate
To be able to communicate your BusPirate you have to know it’s serial number. List the connected devices before you connect your Buspirate with the following command:
$ ls /dev
This command will list all the connected devices. Save them somewhere, and then connect your BusPirate and list the devices again. Find the one that is only present when you connect your BusPirate to your machine.
There you go, mine was:
2. Connect to your device
Use screen to connect to your BusPirate:
$ screen /dev/tty.usbserial-AD01W63E 115200 8N1
The BusPirate console should appear on your terminal. To exit the session press control+a then k and after the prompt press y to kill the screen.
Screen could be weird at first, but there are tons of shortcuts that will help you. Screen manual for osx.
3. Make your life easier
Create an alias for the connection by writing into your ~/.bashrc file.
alias buspirate='screen /dev/tty.usbserial-AD01W63E 115200 8N1'
Source the modified file or restart the terminal, and type in
the BusPirate terminal should open.