# Ht16k33Multi
`Ht16k33Multi` is a library for controlling one or more `Ht16k33` microchips,
which are commonly used to drive 7-segment displays, such as these shown below:
The docs can be found at <https://hexdocs.pm/ht16k33_multi>.
## Features
The main features of `Ht16k33Multi` include:
- Displaying numbers on a 7-segment display
- Displaying words using a special 7-segment font
- Supporting multiple displays (hence the "multi" in the library name).
You can easily chain multiple `Ht16k33` devices to display full sentences or other content across them.
- Utilizing the built-in blinking and dimming features of the `Ht16k33` microchip
## Usage
A typical setup involves using the `Ht16k33` with a 7-segment display and a Raspberry Pi — such as the Raspberry Pi Zero.
You can use the [Nerves Project](https://hexdocs.pm/nerves/getting-started.html)
to build firmware for the Raspberry Pi and other embedded systems like the BeagleBone.
See the [list of supported targets](https://hexdocs.pm/nerves/supported-targets.html) (Nerves Project) for more information.
## Installation
1. **Connect the `Ht16k33` to your embedded system**.
See the [Connect the device to the I²C bus and power](#connect-the-device-to-the-i2c-bus-and-power) section for details.
2. **Add the library to your dependencies**
```elixir
# mix.exs
defp deps do
[
{:ht16k33_multi, "~> 0.1"}
]
end
```
3. **Fetch the dependencies**
```shell
mix deps.get
```
4. **Start the `Ht16k33Multi` GenServer**
You can start it manually in `iex`:
```elixir
iex> Ht16k33Multi.start_link()
```
Or supervise it within your application:
```elixir
children = [
# Single device with default I²C bus ("i2c-1") and address (0x70)
Ht16k33Multi,
# OR with explicit options
{Ht16k33Multi, i2c_bus: "i2c-1", address: 0x70}
]
```
If you're using multiple devices (all on the default I²C bus `"i2c-1"`), assign each a name and address:
```elixir
children = [
{Ht16k33Multi, name: :red_leds, address: 0x70},
{Ht16k33Multi, name: :blue_leds, address: 0x71},
{Ht16k33Multi, name: :yellow_leds, address: 0x72}
]
```
> 💡 See the [Device Address](#device-address) section to learn how to detect your I²C bus and device address.
5. **Write to the display**
Display a message:
```elixir
iex> Ht16k33Multi.write("Hola")
```
Enable blinking:
```elixir
iex> Ht16k33Multi.blinking_on()
```
Dim the display:
```elixir
iex> Ht16k33Multi.dimming(6)
```
## Connect the Device to the I2C Bus and Power
### Using Qwiic with a Raspberry Pi Zero (rpi0)
You can easily chain multiple `Ht16k33` devices using Qwiic cables. This allows you to have multiple displays showing full sentences or other content.
### Wiring Overview:
| Wire Color | Function | Raspberry Pi Zero Pin | GPIO Pin |
|------------|--------------------|-----------------------|-----------|
| Black | GND | 6 | GND |
| Red | 3.3V | 4 | 5V |
| Blue | SDA (Serial Data) | 3 | GPIO2 |
| Yellow | SCL (Serial Clock) | 5 | GPIO3 |
## Device Address
You can detect the I²C bus and device addresses using [`Circuits.I2C`](https://hexdocs.pm/circuits_i2c/Circuits.I2C.html):
```elixir
iex> Circuits.I2C.bus_names()
["i2c-1"]
iex> Circuits.I2C.detect_devices()
Devices on I2C bus "i2c-1":
* 112 (0x70)
1 devices detected on 1 I²C buses
```
The device address is configurable in hardware.
You can set it by soldering the address pins (shown at the bottom right in the image below).
See the [HT16K33 datasheet](https://www.holtek.com/webapi/116711/HT16K33Av102.pdf) for more details.
## Testing
This library has been tested with the **Adafruit 7-Segment LED HT16K33 Backpack**.
## Documentation
The docs can be found at <https://hexdocs.pm/ht16k33_multi>.
