make defaults pico specific

examples/waveshare-epd/epd2in66b/main.go

@@ -27,8 +27,18 @@ func main() {
 
 	println("started")
 
+	// in case you have a Pico module, you can directly use
+	// dev, err := epd2in66b.NewPicoModule()
+
 	display := epd2in66b.New(machine.SPI1)
-	err := display.Configure(epd2in66b.Config{})
+
+	cfg := epd2in66b.Config{
+		DataPin:       machine.GP8,
+		ChipSelectPin: machine.GP9,
+		ResetPin:      machine.GP12,
+		BusyPin:       machine.GP13,
+	}
+	err := display.Configure(cfg)
 	if err != nil {
 		panic(err)
 	}

waveshare-epd/epd2in66b/dev.go

@@ -14,12 +14,6 @@ import (
 const (
 	displayWidth  = 152
 	displayHeight = 296
-
-	// using numerical values to enable generic tinygo compilation
-	dcPin   = 8
-	csPin   = 9
-	rstPin  = 12
-	busyPin = 13
 )
 
 const Baudrate = 4_000_000 // 4 MHz
@@ -42,48 +36,26 @@ type Device struct {
 	redBuffer   []byte
 }
 
-// New allocates a new device. The SPI for the built-in header to be used is picos machine.SPI1 at 4 MHz baudrate.
+// New allocates a new device.
 // The bus is expected to be configured and ready for use.
 func New(bus drivers.SPI) Device {
 	pixelCount := displayWidth * displayHeight
 
 	bufLen := pixelCount / 8
 
 	return Device{
-		bus:  bus,
-		cs:   csPin,
-		dc:   dcPin,
-		rst:  rstPin,
-		busy: busyPin,
-
+		bus:         bus,
 		blackBuffer: make([]byte, bufLen),
 		redBuffer:   make([]byte, bufLen),
 	}
 }
 
 // Configure configures the device and its pins. The 'zero' config will fall back to the defaults.
-//
-// Default pins are:
-//
-//	Data       = GP8
-//	ChipSelect = GP9
-//	Reset      = GP12
-//	Busy       = GP13
 func (d *Device) Configure(c Config) error {
-	if c.ChipSelectPin > 0 {
-		d.cs = c.ChipSelectPin
-	}
-	if c.DataPin > 0 {
-		d.dc = c.DataPin
-	}
-
-	if c.ResetPin > 0 {
-		d.rst = c.ResetPin
-	}
-
-	if c.BusyPin > 0 {
-		d.busy = c.BusyPin
-	}
+	d.cs = c.ChipSelectPin
+	d.dc = c.DataPin
+	d.rst = c.ResetPin
+	d.busy = c.BusyPin
 
 	d.cs.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	d.dc.Configure(machine.PinConfig{Mode: machine.PinOutput})

waveshare-epd/epd2in66b/dev_pico.go

@@ -0,0 +1,34 @@
+//go:build pico
+
+package epd2in66b
+
+import (
+	"machine"
+)
+
+// DefaultConfig contains the default config for the https://www.waveshare.com/wiki/Pico-ePaper-2.66 module
+var DefaultConfig = Config{
+	DataPin:       machine.GP8,
+	ChipSelectPin: machine.GP9,
+	ResetPin:      machine.GP12,
+	BusyPin:       machine.GP13,
+}
+
+// NewPicoModule allocates a new device backed by the https://www.waveshare.com/wiki/Pico-ePaper-2.66 module
+// This will also configure the SPI1 bus and configure the device with the DefaultConfig
+func NewPicoModule() (Device, error) {
+	spi := machine.SPI1
+
+	if err := spi.Configure(machine.SPIConfig{
+		Frequency: Baudrate,
+	}); err != nil {
+		return Device{}, err
+	}
+
+	dev := New(spi)
+	if err := dev.Configure(DefaultConfig); err != nil {
+		return dev, err
+	}
+
+	return dev, nil
+}