Swift package SenseHat for Raspberry Pi Sense Hat

Features:

• ✅ blink with LED - that what everyone starts from playing with Raspberry Pi;
• ✅ get/set color to individual pixels;
• ✅ set color to all pixels in one shot;
• ✅ get/set all pixels in one shot (to/from Data);
• ✅ show 8x8 characters on LCD matrix (supported ascii, extended latin, box drawings elements, block elements, Hiragana, Greek, sga);
• ✅ show arbitrary text (8x8 font, horizontal scroll);
• ✅ rotating of LED matrix 0º/90º/180º/270º;
• ✅ set orientation of LED matrix 0º/90º/180º/270º and make all get/set primitives respect it;
• ✅ read joystick;
• ✅ read humidity and pressure sensors;
• ✅ read gyroscope/accelerometer/magnitometer sensors;
• ✅ snake game;
• ✅ life game;

TODO:

• improve gyroscope/accelerometer/magnetometer sensors reading;
• add conversion of RGB color to Rgb565;
• add Cyrillic font 8x8;
• add 3x5 font;
• replace C fonts with Swift ones;
• show arbitrary image on LED matrix;
• show preprocessed video;
• menu to show readings from any of available sensors;
• mode for rotating screen depending on gyro readings;
• emulator of SenseHat LED matrix for Web;
• Kalman filtering for accelerometer/gyro/magnetometer;
• add analog clock demo app.

Usage

Instantiating

// Look over all frame buffer devices in `/dev/` for one of Sense Hat. 
// Use default orientation `.up`
guard let senseHat = SenseHat() else {
    fatalError("Can't initialise Raspberry Pi Sense Hat")
}

Parameter orientation could be used for other orientations” SenseHat(orientation: .left). Parameter frameBufferDevice could be use for specific frame buffer device: SenseHat(frameBufferDevice: "/dev/fb0"). Both parameters could be used: SenseHat(frameBufferDevice: "/dev/fb0", orientation: .down).

Parameter orientation defines where top of the LED matrix will be. Here are example of the same character "1" shown with different orientations:

.up	.left	.right	.down
			

Set all LEDs of matrix to specific color

senseHat.set(color: .red) // sets all LEDs of matrix to red


senseHat.set(color: .black) // sets all LEDs of matrix to black, literally turns them off


Set specific LED of matrix to specific color

senseHat.set(color: .black) // clear
senseHat.set(x: 0, y: 0, color: .white) // set most top left LED to white using function syntax
senseHat[7, 7] = .green // set most bottom right LED to green using subscript syntax


Coordinates x and y should belong to 0..<7 range.

Show character on LED matrix

senseHat.show(character: Character("A"), color: .blue)


senseHat.show(character: Character("π"), color: .yellow, background: .blue)


Show string on LED matrix

senseHat.show(string: "Hello! ", secPerChar: 0.5, color: .yellow, background: .blue)


senseHat.orientation = .left
senseHat.show(string: "Απόλλων ", secPerChar: 0.5, color: .red, background: .darkGray)


senseHat.orientation = .right
senseHat.show(string: "ここからそこまで ", secPerChar: 0.5, color: .white, background: .brown)


senseHat.orientation = .down
senseHat.show(string: "Fußgängerübergänge ", secPerChar: 0.5, color: .white, background: .purple)


Reading humidity sensor

if let h = senseHat.humidity() {
    let strH = String(format: "%.1lf", h.H_rH)
    senseHat.show(string: "Humidity \(strH)% rH ", secPerChar: 0.5, color: .yellow, background: .black)
    let strT = String(format: "%.1lf", h.T_DegC)
    senseHat.show(string: "Temperature \(strT)ºC", secPerChar: 0.5, color: .yellow, background: .black)
} else {
    print("Cannot read humidity sensor")
}


Reading pressure sensor

if let p = senseHat.pressure() {
    let strP = String(format: "%.1lf", p.P_hPa)
    let strT = String(format: "%.1lf", p.T_DegC)
    senseHat.show(string: "Pressure \(strP) hPa ", secPerChar: 0.5, color: .yellow, background: .black)
    senseHat.show(string: "Temperature \(strT)ºC", secPerChar: 0.5, color: .yellow, background: .black)
} else {
    print("Cannot read pressure sensor")
}


Useful links

Unfortunately Data sheet or Programmer’s manual for Raspberry Pi Sense Hat doesn’t exist or I have failed to find it. Here are some useful links:

• Official page on raspberrypi.org Sense HAT;
• Astro Pi: Flight Hardware Tech Specs names all sensors of SenseHat with links on datasheets;
• Official documentation Documentation for Sense HAT;
• Official Python module sense-hat;
• Source of Python module sense-hat;
• Getting started with the Sense HAT;
• Rust library sensehat-screen where it’s explained how RGB is packed in two bytes in so called Rgb565;
• Linux The Frame Buffer Device API used to access pixel buffer;
• Data sheet for LSM9DS1, this might be useful Reading from FIFO;
• Guide to install Swift on Raspberry Pi buildSwiftOnARM used to install prebuilt Swift 5.1.5 TODO: describe what I’ve done differently;
• 3D printing Astro Pi case.