README.md

Analog Terminal Bell Software

The Analog Terminal Bell uses the GPIO pin of an MCP2221a to fire a solenoid and hit the bell. This is all done over USB.

Configuring the Analog Terminal Bell

By default, the MCP2221a doesn't use GP0 as a general purpose IO, so we need to configure it before using it. This only needs to be done once, ever. I use a Ruby library called "UChip" to do the initial configuration:

require "uchip/mcp2221"

# This example changes the "startup" GPIO settings of the chip.

# Find the first connected chip
chip = UChip::MCP2221.first || raise("Couldn't find the chip!")

# Get the GPIO settings
settings = chip.gp_settings

settings.gp0_designation = 0   # We want to use this pin as a GPIO
settings.gp0_output_value = 0  # Set the default value to 0
settings.gp0_direction = 0     # Set the direction to output

# Write the settings to the chip.  Next time the chip starts, the default
# settings for GP0 will reflect these settings
chip.gp_settings = settings

Controlling the Analog Terminal Bell

The Analog Terminal Bell can be controlled with Circuit Python, but I don't know how. I've been testing it with a Ruby library called "UChip". To install the gem, just do gem install uchip.

Here is the code to control the bell with Ruby:

require "uchip/mcp2221"

def hit_bell pin
  pin.value = 0
  pin.value = 1
  sleep 0.009
  pin.value = 0
end

# Find the first connected chip
chip = UChip::MCP2221.first || raise("Couldn't find the chip!")

pin = chip.pin 0
pin.output!

loop do
  hit_bell pin
  sleep 2
end

Analog Terminal Bell and iTerm2

Currently the Analog Terminal Bell requires a custom build of iTerm2 to work. Building from this branch will enable the Analog Terminal Bell feature in iTerm2.