ateccx08: inttial implementation for ATECCx08

This working implementation for the ATECCx08 family of cryptgraphic processors
has random number generation and other needed supporting functions.

It also includes a sample of how to connect it to the Go crypto/rand package.

More cryptographic functions await a future interation.

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

examples/ateccx08/random/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"machine"
+
+	"crypto/rand"
+	"encoding/hex"
+	"time"
+
+	"tinygo.org/x/drivers/ateccx08"
+)
+
+var atecc *ateccx08.Device
+
+func main() {
+	time.Sleep(5 * time.Second)
+	println("Looking for ATECCx08...")
+
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	atecc = ateccx08.New(machine.I2C0)
+	atecc.Configure()
+
+	if !atecc.Connected() {
+		for {
+			println("could not connect to ATECCx08")
+			time.Sleep(time.Second)
+		}
+	}
+
+	version, _ := atecc.Version()
+
+	println(version.String(), "started")
+
+	if !atecc.IsLocked() {
+		for {
+			println(version.String(), "is not locked. Random numbers will not actually be random.")
+			time.Sleep(time.Second)
+		}
+	}
+
+	var result [13]byte
+	for {
+		rand.Read(result[:])
+		encodedString := hex.EncodeToString(result[:])
+		println(encodedString)
+		time.Sleep(500 * time.Millisecond)
+	}
+}