sdcard: add support for spi sdcard driver

examples/sdcard/console/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/sdcard"
+)
+
+var (
+	spi    machine.SPI
+	csPin  machine.Pin
+	ledPin machine.Pin
+)
+
+func main() {
+	waitSerial()
+	fmt.Printf("sdcard console\r\n")
+
+	led := ledPin
+	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	sd := sdcard.New(spi, csPin)
+	err := sd.Configure()
+	if err != nil {
+		fmt.Printf("%s\r\n", err.Error())
+		for {
+			time.Sleep(time.Hour)
+		}
+	}
+
+	go RunFor(&sd)
+
+	for {
+		led.High()
+		time.Sleep(200 * time.Millisecond)
+		led.Low()
+		time.Sleep(200 * time.Millisecond)
+	}
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}