defmodule ST7789 do
@moduledoc """
ST7789 Elixir driver
"""
use Bitwise
@enforce_keys [:spi, :gpio, :opts]
defstruct [:spi, :gpio, :opts]
@doc """
New connection to an ST7789
- **port**: SPI port number
Default value: `0`
- **cs**: SPI chip-select number (0 or 1 for BCM).
Default value: `0`.
- **backlight**: Pin for controlling backlight
Default value: `nil`.
- **rst**: Reset pin for ST7789
Default value: `nil`.
- **width**: Width of display connected to ST7789
Default value: `240`.
- **height**: Height of display connected to ST7789
Default value: `240`.
- **offset_top**: Offset to top row
Default value: `0`.
- **offset_left**: Offset to left column
Default value: `0`.
- **invert**: Invert display
Default value: `true`.
- **speed_hz**: SPI speed (in Hz)
Default value: `400_0000`.
**return**: `%ST7789{}`
## Example
```elixir
# default
# assuming device at /dev/spidev0.0
# DC connects to BCM 9
# BL not connected
# RST not connected
# SPI speed: 4MHz
disp = ST7789.new()
```
```elixir
# specify init arguments
port = 0 # spi bus 0
cs = 0 # BCM 8 / CE 0
dc = 9 # BCM 9
backlight = 17 # BCM 17
speed_hz = 80 * 1000 * 1000 # 80MHz
disp = ST7789.new(port: port, cs: cs, dc: dc, backlight: backlight, speed_hz: speed_hz)
```
"""
@doc functions: :exported
def new(opts \\ []) do
port = opts[:port] || 0
cs = opts[:cs] || 0
dc = opts[:dc] || 9
speed_hz = opts[:speed_hz] || 4_000_000
invert = opts[:invert] || true
width = opts[:width] || 240
height = opts[:height] || 240
offset_top = opts[:offset_top] || 0
offset_left = opts[:offset_left] || 0
backlight = opts[:backlight]
rst = opts[:rst]
{:ok, spi} = Circuits.SPI.open("spidev#{port}.#{cs}", speed_hz: speed_hz)
# Set DC as output.
{:ok, gpio_dc} = Circuits.GPIO.open(dc, :output)
# Setup backlight as output (if provided).
gpio_backlight = init_backlight(backlight)
# Setup reset as output (if provided).
gpio_rst = init_reset(rst)
%ST7789{
spi: spi,
gpio: [
dc: gpio_dc,
backlight: gpio_backlight,
rst: gpio_rst
],
opts: [
port: port,
cs: cs,
dc: dc,
speed_hz: speed_hz,
invert: invert,
width: width,
height: height,
offset_top: offset_top,
offset_left: offset_left,
backlight: backlight,
rst: rst
]
}
|> ST7789.reset()
|> init()
end
@doc """
Reset the display, if reset pin is connected.
- **self**: `%ST7789{}`
**return**: `self`
"""
@doc functions: :exported
def reset(self=%ST7789{gpio: gpio}) do
gpio_rst = gpio[:rst]
if gpio_rst != nil do
Circuits.GPIO.write(gpio_rst, 1)
:timer.sleep(500)
Circuits.GPIO.write(gpio_rst, 0)
:timer.sleep(500)
Circuits.GPIO.write(gpio_rst, 1)
:timer.sleep(500)
end
self
end
@doc """
Write the provided 16bit RGB565 image to the hardware.
- **self**: `%ST7789{}`
- **image_data**: Should be 16bit RGB565 format and the same dimensions (width x height x 3) as the display hardware.
**return**: `self`
"""
@doc functions: :exported
def display_565(self, image_data) when is_binary(image_data) do
display_565(self, :binary.bin_to_list(image_data))
end
def display_565(self, image_data) when is_list(image_data) do
self
|> set_window(x0: 0, y0: 0, x1: nil, y2: nil)
|> send(image_data, true, 4096)
end
@doc """
Write the provided 24bit RGB888 image to the hardware.
- **self**: `%ST7789{}`
- **image_data**: Should be 24bit RGB888 format and the same dimensions (width x height x 3) as the display hardware.
**return**: `self`
"""
@doc functions: :exported
def display(self, image_data) when is_list(image_data) do
display_565(self, to_rgb565(image_data))
end
def display(self, image_data) when is_binary(image_data) do
display(self, :binary.bin_to_list(image_data))
end
@doc """
Set backlight status
- **self**: `%ST7789{}`
- **status**: either `:on` or `:off`
**return**: `self`
"""
@doc functions: :exported
def set_backlight(self=%ST7789{gpio: gpio}, :on) do
backlight = gpio[:backlight]
if backlight != nil do
Circuits.GPIO.write(backlight, 1)
end
self
end
def set_backlight(self=%ST7789{gpio: gpio}, :off) do
backlight = gpio[:backlight]
if backlight != nil do
Circuits.GPIO.write(backlight, 0)
end
self
end
@doc """
Write a byte to the display as command data.
- **self**: `%ST7789{}`
- **cmd**: command data
**return**: `self`
"""
@doc functions: :exported
def command(self, cmd) when is_integer(cmd) do
send(self, cmd, false)
end
@doc """
Write a byte or array of bytes to the display as display data.
- **self**: `%ST7789{}`
- **data**: display data
**return**: `self`
"""
@doc functions: :exported
def data(self, data) do
send(self, data, true)
end
@doc """
Send bytes to the ST7789
- **self**: `%ST7789{}`
- **bytes**: The bytes to be sent to `self`
- `when is_integer(bytes)`,
`sent` will take the 8 least-significant bits `[band(bytes, 0xFF)]`
and send it to `self`
- `when is_list(bytes)`, `bytes` will be casting to bitstring and then sent
to `self`
- **is_data**:
- `true`: `bytes` will be sent as data
- `false`: `bytes` will be sent as commands
- **chunk_size**: Indicates how many bytes will be send in a single write call
**return**: `self`
"""
@doc functions: :exported
def send(self, bytes, is_data, chunk_size \\ 4096)
def send(self=%ST7789{}, bytes, true, chunk_size) do
send(self, bytes, 1, chunk_size)
end
def send(self=%ST7789{}, bytes, false, chunk_size) do
send(self, bytes, 0, chunk_size)
end
def send(self=%ST7789{}, bytes, is_data, chunk_size)
when (is_data == 0 or is_data == 1) and is_integer(bytes) do
send(self, [Bitwise.band(bytes, 0xFF)], is_data, chunk_size)
end
def send(self=%ST7789{gpio: gpio, spi: spi}, bytes, is_data, chunk_size)
when (is_data == 0 or is_data == 1) and is_list(bytes) do
gpio_dc = gpio[:dc]
if gpio_dc != nil do
Circuits.GPIO.write(gpio_dc, is_data)
for xfdata <-
bytes
|> Enum.chunk_every(chunk_size)
|> Enum.map(& Enum.into(&1, <<>>, fn bit -> <<bit :: 8>> end)) do
{:ok, _ret} = Circuits.SPI.transfer(spi, xfdata)
end
self
else
{:error, "gpio[:dc] is nil"}
end
end
defp to_rgb565(image_data) when is_list(image_data) do
image_data
|> Enum.chunk_every(3)
|> Enum.map(fn [r,g,b] ->
bor(
bor(
bsl(band(r, 0xF8), 8),
bsl(band(g, 0xFC), 3)),
bsr(band(b, 0xF8), 3))
end)
|> Enum.into(<<>>, fn bit -> <<bit :: 16>> end)
|> :binary.bin_to_list()
end
defp init(self=%ST7789{opts: board}) do
invert = board[:invert]
# Initialize the display.
command(self, kSWRESET()) # Software reset
:timer.sleep(150) # delay 150 ms
self
|> command(kMADCTL())
|> data(0x70)
|> command(kFRMCTR2())
|> data(0x0C)
|> data(0x0C)
|> data(0x00)
|> data(0x33)
|> data(0x33)
|> command(kCOLMOD())
|> data(0x05)
|> command(kGCTRL())
|> data(0x14)
|> command(kVCOMS())
|> data(0x37)
|> command(kLCMCTRL()) # Power control
|> data(0x2C)
|> command(kVDVVRHEN()) # Power control
|> data(0x01)
|> command(kVRHS()) # Power control
|> data(0x12)
|> command(kVDVS()) # Power control
|> data(0x20)
|> command(0xD0)
|> data(0xA4)
|> data(0xA1)
|> command(kFRCTRL2())
|> data(0x0F)
|> command(kGMCTRP1()) # Set Gamma
|> data(0xD0)
|> data(0x04)
|> data(0x0D)
|> data(0x11)
|> data(0x13)
|> data(0x2B)
|> data(0x3F)
|> data(0x54)
|> data(0x4C)
|> data(0x18)
|> data(0x0D)
|> data(0x0B)
|> data(0x1F)
|> data(0x23)
|> command(kGMCTRN1()) # Set Gamma
|> data(0xD0)
|> data(0x04)
|> data(0x0C)
|> data(0x11)
|> data(0x13)
|> data(0x2C)
|> data(0x3F)
|> data(0x44)
|> data(0x51)
|> data(0x2F)
|> data(0x1F)
|> data(0x1F)
|> data(0x20)
|> data(0x23)
|> init_invert(invert)
|> command(kSLPOUT())
|> command(kDISPON())
:timer.sleep(100)
self
end
defp init_backlight(nil), do: nil
defp init_backlight(backlight) when backlight >= 0 do
{:ok, gpio} = Circuits.GPIO.open(backlight, :output)
Circuits.GPIO.write(gpio, 0)
:timer.sleep(100)
Circuits.GPIO.write(gpio, 1)
gpio
end
defp init_backlight(_), do: nil
defp init_reset(nil), do: nil
defp init_reset(rst) when rst >= 0 do
{:ok, gpio} = Circuits.GPIO.open(rst, :output)
gpio
end
defp init_reset(_), do: nil
defp init_invert(self, true) do
# Invert display
command(self, kINVON())
end
defp init_invert(self, _) do
# Don't invert display
command(self, kINVOFF())
end
defp set_window(self=%ST7789{opts: board}, opts = [x0: 0, y0: 0, x1: nil, y2: nil]) do
width = board[:width]
height = board[:height]
offset_top = board[:offset_top]
offset_left = board[:offset_left]
x0 = opts[:x0]
x1 = opts[:x1]
x1 = if x1 == nil, do: width - 1
y0 = opts[:y0]
y1 = opts[:y1]
y1 = if y1 == nil, do: height - 1
y0 = y0 + offset_top
y1 = y1 + offset_top
x0 = x0 + offset_left
x1 = x1 + offset_left
self
|> command(kCASET())
|> data(bsr(x0, 8))
|> data(band(x0, 0xFF))
|> data(bsr(x1, 8))
|> data(band(x1, 0xFF))
|> command(kRASET())
|> data(bsr(y0, 8))
|> data(band(y0, 0xFF))
|> data(bsr(y1, 8))
|> data(band(y1, 0xFF))
|> command(kRAMWR())
end
@doc functions: :constants
def kSWRESET, do: 0x01
@doc functions: :constants
def kSLPOUT, do: 0x11
@doc functions: :constants
def kINVOFF, do: 0x20
@doc functions: :constants
def kINVON, do: 0x21
@doc functions: :constants
def kDISPON, do: 0x29
@doc functions: :constants
def kCASET, do: 0x2A
@doc functions: :constants
def kRASET, do: 0x2B
@doc functions: :constants
def kRAMWR, do: 0x2C
@doc functions: :constants
def kMADCTL, do: 0x36
@doc functions: :constants
def kCOLMOD, do: 0x3A
@doc functions: :constants
def kFRMCTR2, do: 0xB2
@doc functions: :constants
def kGCTRL, do: 0xB7
@doc functions: :constants
def kVCOMS, do: 0xBB
@doc functions: :constants
def kLCMCTRL, do: 0xC0
@doc functions: :constants
def kVDVVRHEN, do: 0xC2
@doc functions: :constants
def kVRHS, do: 0xC3
@doc functions: :constants
def kVDVS, do: 0xC4
@doc functions: :constants
def kFRCTRL2, do: 0xC6
@doc functions: :constants
def kGMCTRP1, do: 0xE0
@doc functions: :constants
def kGMCTRN1, do: 0xE1
end
