spi: add support for MCP3004 A/D converter

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

drivers/spi/mcp3004.go

@@ -0,0 +1,74 @@
+package spi
+
+import (
+	"strconv"
+
+	"gobot.io/x/gobot"
+)
+
+// MCP3004Driver is a driver for the MCP3008 A/D converter.
+type MCP3004Driver struct {
+	name       string
+	connector  Connector
+	connection Connection
+}
+
+// NewMCP3004Driver creates a new Gobot Driver for MCP3004Driver A/D converter
+//
+// Params:
+//      a *Adaptor - the Adaptor to use with this Driver
+//
+func NewMCP3004Driver(a Connector) *MCP3004Driver {
+	d := &MCP3004Driver{
+		name:      gobot.DefaultName("MCP3008"),
+		connector: a,
+	}
+	return d
+}
+
+// Name returns the name of the device.
+func (d *MCP3004Driver) Name() string { return d.name }
+
+// SetName sets the name of the device.
+func (d *MCP3004Driver) SetName(n string) { d.name = n }
+
+// Connection returns the Connection of the device.
+func (d *MCP3004Driver) Connection() gobot.Connection { return d.connection.(gobot.Connection) }
+
+// Start initializes the driver.
+func (d *MCP3004Driver) Start() (err error) {
+	bus := d.connector.GetSpiDefaultBus()
+	mode := d.connector.GetSpiDefaultMode()
+	maxSpeed := d.connector.GetSpiDefaultMaxSpeed()
+	d.connection, err = d.connector.GetSpiConnection(bus, mode, maxSpeed)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Halt stops the driver.
+func (d *MCP3004Driver) Halt() (err error) {
+	d.connection.Close()
+	return
+}
+
+// Read reads the current analog data for the desired channel.
+func (d *MCP3004Driver) Read(channel int) (int, error) {
+	tx := make([]byte, 3)
+	tx[0] = 0x01
+	tx[1] = 0x80 + (byte(channel) << 4)
+	tx[2] = 0x00
+
+	d.connection.Tx(tx, nil)
+
+	return 0, nil
+}
+
+// AnalogRead returns value from analog reading of specified pin
+func (d *MCP3004Driver) AnalogRead(pin string) (value int, err error) {
+	channel, _ := strconv.Atoi(pin)
+	value, err = d.Read(channel)
+
+	return
+}

drivers/spi/mcp3004_test.go

@@ -0,0 +1,35 @@
+package spi
+
+import (
+	"testing"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/drivers/aio"
+	"gobot.io/x/gobot/gobottest"
+)
+
+var _ gobot.Driver = (*MCP3004Driver)(nil)
+
+// must implement the AnalogReader interface
+var _ aio.AnalogReader = (*MCP3004Driver)(nil)
+
+func initTestMCP3004Driver() *MCP3004Driver {
+	d := NewMCP3004Driver(&TestConnector{})
+	return d
+}
+
+func TestMCP3004DriverStart(t *testing.T) {
+	d := initTestMCP3004Driver()
+	gobottest.Assert(t, d.Start(), nil)
+}
+
+func TestMCP3004DriverHalt(t *testing.T) {
+	d := initTestMCP3004Driver()
+	d.Start()
+	gobottest.Assert(t, d.Halt(), nil)
+}
+
+func TestMCP3004DriverRead(t *testing.T) {
+	d := initTestMCP3004Driver()
+	d.Start()
+}