scd4x: implement driver for CO2 sensor

Signed-off-by: deadprogram <ron@hybridgroup.com>

examples/scd4x/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/scd4x"
+)
+
+var (
+	i2c    = machine.I2C0
+	sensor = scd4x.New(i2c)
+)
+
+func main() {
+	time.Sleep(1500 * time.Millisecond)
+
+	i2c.Configure(machine.I2CConfig{})
+	if err := sensor.Configure(); err != nil {
+		println(err)
+	}
+
+	time.Sleep(1500 * time.Millisecond)
+
+	if err := sensor.StartPeriodicMeasurement(); err != nil {
+		println(err)
+	}
+
+	time.Sleep(1500 * time.Millisecond)
+
+	for {
+		co2, err := sensor.ReadCO2()
+		if err != nil {
+			println(err)
+		}
+		println("CO2", co2)
+		time.Sleep(time.Second)
+	}
+}