This package provides an interface for controlling OLED displays using the common SSD1322 chipset, as available here (or many other vendors). In addition to supporting a number of bitmap formats for display, you can also control various aspects of the display such as contrast values, enabling / disabling the display and other tasks.

This library requires a 4 wire SPI connection to the display board, in addition to two GPIO lines. All connections are made using the Elixir Circuits library.

If using this library via Nerves and wiring your hardware up in the manner described in the 'Putting it together' section of this article, the default values will be sufficient. In other situations, you may need to explicitly set hardware parameters as detailed in the next section.

Common usage looks like so:

# Initialize your connection
{:ok, pid} = SSD1322.start_link()

# You can also override a bunch of options if needed:
{:ok, pid} = SSD1322.start_link(spi_connection_opts: [spi_dev: "spidev0.0", dc_pin: 24, reset_pin: 25], width: 256, height: 64, name: "my_display")

# Display the image defined by data. data is a binary containing row-wise 
# 4-bit greyscale pixel data in linear order. It follows that there data is
# W x H / 2 bytes long. Check out github.com/mtrudel/ex_paint for a library that
# can produce this format with little effort
SSD1322.draw(pid, data)

# You can also turn the display on and off
SSD1322.display_on(pid)
SSD1322.display_off(pid)

# Set the contrast to a value between 0 and 255
SSD1322.contrast(pid, contrast)

# Clear the display to a given grey (black by default)
SSD1322.clear(pid, grey \\ 0x00)

# Or reset the connection if something goes wrong
SSD1322.reset(pid)

Note that although this library serializes access for callers sharing a single connection instance, neither this library nor the underlying Elixir Circuits library provide any protection against multiple concurrent access to an attached display by across multiple connection instances.

This package can be installed by adding ssd1322 to your list of dependencies in mix.exs:

def deps do
  [
    {:ssd1322, "~> 0.1.0"}
  ]
end

Docs can be found at https://hexdocs.pm/ssd1322.