spi: add MCP3002 A/D converter

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

README.md

@@ -288,6 +288,7 @@ a shared set of drivers provided using the `gobot/drivers/spi` package:
 
 - [SPI](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus) <=> [Drivers](https://github.com/hybridgroup/gobot/tree/master/drivers/spi)
 	- APA102 Programmable LEDs
+	- MCP3002 Analog/Digital Converter
 	- MCP3004 Analog/Digital Converter
 	- MCP3008 Analog/Digital Converter
 

drivers/spi/README.MD

@@ -15,6 +15,7 @@ Gobot has a extensible system for connecting to hardware devices.
 The following spi Devices are currently supported:
 
 - APA102 Programmable LEDs
+- MCP3002 Analog/Digital Converter
 - MCP3004 Analog/Digital Converter
 - MCP3008 Analog/Digital Converter
 - GoPiGo3 Robot

drivers/spi/mcp3002.go

@@ -0,0 +1,86 @@
+package spi
+
+import (
+	"errors"
+	"strconv"
+
+	"gobot.io/x/gobot"
+)
+
+// MCP3002DriverMaxChannel is the number of channels (plus one) of this A/D converter.
+const MCP3002DriverMaxChannel = 1
+
+// MCP3002Driver is a driver for the MCP3002 A/D converter.
+type MCP3002Driver struct {
+	name       string
+	connector  Connector
+	connection Connection
+}
+
+// NewMCP3002Driver creates a new Gobot Driver for MCP3002 A/D converter
+//
+// Params:
+//      a *Adaptor - the Adaptor to use with this Driver
+//
+func NewMCP3002Driver(a Connector) *MCP3002Driver {
+	d := &MCP3002Driver{
+		name:      gobot.DefaultName("MCP3002"),
+		connector: a,
+	}
+	return d
+}
+
+// Name returns the name of the device.
+func (d *MCP3002Driver) Name() string { return d.name }
+
+// SetName sets the name of the device.
+func (d *MCP3002Driver) SetName(n string) { d.name = n }
+
+// Connection returns the Connection of the device.
+func (d *MCP3002Driver) Connection() gobot.Connection { return d.connection.(gobot.Connection) }
+
+// Start initializes the driver.
+func (d *MCP3002Driver) 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 *MCP3002Driver) Halt() (err error) {
+	d.connection.Close()
+	return
+}
+
+// Read reads the current analog data for the desired channel.
+func (d *MCP3002Driver) Read(channel int) (result int, err error) {
+	if channel < 0 || channel > MCP3002DriverMaxChannel {
+		return 0, errors.New("Invalid channel for read")
+	}
+
+	tx := make([]byte, 2)
+	tx[0] = 0x68 + (byte(channel) << 4)
+	tx[1] = 0x00
+
+	rx := make([]byte, 2)
+
+	err = d.connection.Tx(tx, rx)
+	if err == nil && len(rx) == 2 {
+		result = int(((rx[0] & 0x3) << 8) + rx[1])
+	}
+
+	return result, err
+}
+
+// AnalogRead returns value from analog reading of specified pin
+func (d *MCP3002Driver) AnalogRead(pin string) (value int, err error) {
+	channel, _ := strconv.Atoi(pin)
+	value, err = d.Read(channel)
+
+	return
+}

drivers/spi/mcp3002_test.go

@@ -0,0 +1,37 @@
+package spi
+
+import (
+	"testing"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/drivers/aio"
+	"gobot.io/x/gobot/gobottest"
+)
+
+var _ gobot.Driver = (*MCP3002Driver)(nil)
+
+// must implement the AnalogReader interface
+var _ aio.AnalogReader = (*MCP3002Driver)(nil)
+
+func initTestMCP3002Driver() *MCP3002Driver {
+	d := NewMCP3002Driver(&TestConnector{})
+	return d
+}
+
+func TestMCP3002DriverStart(t *testing.T) {
+	d := initTestMCP3002Driver()
+	gobottest.Assert(t, d.Start(), nil)
+}
+
+func TestMCP3002DriverHalt(t *testing.T) {
+	d := initTestMCP3002Driver()
+	d.Start()
+	gobottest.Assert(t, d.Halt(), nil)
+}
+
+func TestMCP3002DriverRead(t *testing.T) {
+	d := initTestMCP3002Driver()
+	d.Start()
+
+	// TODO: actual read test
+}

drivers/spi/mcp3004.go

@@ -17,14 +17,14 @@ type MCP3004Driver struct {
 	connection Connection
 }
 
-// NewMCP3004Driver creates a new Gobot Driver for MCP3004Driver A/D converter
+// NewMCP3004Driver creates a new Gobot Driver for MCP3004 A/D converter
 //
 // Params:
 //      a *Adaptor - the Adaptor to use with this Driver
 //
 func NewMCP3004Driver(a Connector) *MCP3004Driver {
 	d := &MCP3004Driver{
-		name:      gobot.DefaultName("MCP3008"),
+		name:      gobot.DefaultName("MCP3004"),
 		connector: a,
 	}
 	return d
@@ -65,14 +65,14 @@ func (d *MCP3004Driver) Read(channel int) (result int, err error) {
 
 	tx := make([]byte, 3)
 	tx[0] = 0x01
-	tx[1] = 0x80 + (byte(channel) << 4)
+	tx[1] = byte(8+channel) << 4
 	tx[2] = 0x00
 
 	rx := make([]byte, 3)
 
 	err = d.connection.Tx(tx, rx)
 	if err == nil && len(rx) == 3 {
-		result = int(((rx[1] & 0x03) << 8) + rx[2])
+		result = int(((rx[1] & 0x3) << 8) + rx[2])
 	}
 
 	return result, err

drivers/spi/mcp3008.go

@@ -65,14 +65,14 @@ func (d *MCP3008Driver) Read(channel int) (result int, err error) {
 
 	tx := make([]byte, 3)
 	tx[0] = 0x01
-	tx[1] = 0x80 + (byte(channel) << 4)
+	tx[1] = byte(8+channel) << 4
 	tx[2] = 0x00
 
 	rx := make([]byte, 3)
 
 	err = d.connection.Tx(tx, rx)
 	if err == nil && len(rx) == 3 {
-		result = int(((rx[1] & 0x03) << 8) + rx[2])
+		result = int(((rx[1] & 0x3) << 8) + rx[2])
 	}
 
 	return result, err