nerves_config_pin

A BeagleBone config-pin wrapper for use in Elixir Nerves projects.

Usage

Overlays

The BeagleBone cape manager is not available in a Nerves system. Instead, the overlays are specified by setting U-Boot environment variables. Configuration of capes/overlays is out of the scope of this library. Utilize Nerves.Runtime.KV or provisioning.conf to configure overlays.

Example Commands

The following functions accept the number of the header followed by the number of the pin on that header. See the system reference manual for the pin mux table.

Set header 9, pin 12 to gpio pull-up:

iex> ConfigPin.set(9, 12, :gpio_pu)
:ok

Query the pin configuration for header 9, pin 12:

iex> ConfigPin.query(9, 12)       
{:ok, %{direction: :in, header: 9, mode: :default, pin: 12, value: 1}}

List the valid pin mux modes for header 9, pin 12:

iex> ConfigPin.list_modes(9, 12)
{:ok, [:default, :gpio, :gpio_pu, :gpio_pd, :gpio_input]}

Print info for header 9, pin 12:

iex> ConfigPin.info(9, 12) 
# Pin name: P9_12
# Function if no cape loaded: gpio
# Function if cape loaded: default gpio gpio_pu gpio_pd gpio_input
# Function information: gpio1_28 default gpio1_28 gpio1_28 gpio1_28 gpio1_28
# Kernel GPIO id: 60
# PRU GPIO id: 92

:ok

Set Configuration From A File

A list of pin configurations can be defined in a text file. The format is <header>_<pin> <mode>\n. Comments and white-space are allowed. Each configuration must end with a line terminator.

The file is passed directly to config-pin and is not processed by this library.

Example file:

# <header>_<pin> <mode>
P9_11 gpio_pu
P9_12 gpio_pd

Setting the configuration:

iex> ConfigPin.set_from_file("/root/pinmux")
:ok