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neurosky_driver.go
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neurosky_driver.go
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package neurosky
import (
"bytes"
"github.com/hybridgroup/gobot"
)
const BTSync byte = 0xAA
// Extended code
const CodeEx byte = 0x55
// POOR_SIGNAL quality 0-255
const CodeSignalQuality byte = 0x02
// ATTENTION eSense 0-100
const CodeAttention byte = 0x04
// MEDITATION eSense 0-100
const CodeMeditation byte = 0x05
// BLINK strength 0-255
const CodeBlink byte = 0x16
// RAW wave value: 2-byte big-endian 2s-complement
const CodeWave byte = 0x80
// ASIC EEG POWER 8 3-byte big-endian integers
const CodeAsicEEG byte = 0x83
type NeuroskyDriver struct {
name string
connection gobot.Connection
gobot.Eventer
}
type EEG struct {
Delta int
Theta int
LoAlpha int
HiAlpha int
LoBeta int
HiBeta int
LoGamma int
MidGamma int
}
// NewNeuroskyDriver creates a NeuroskyDriver by name
// and adds the following events:
//
// extended - user's current extended level
// signal - shows signal strength
// attention - user's current attention level
// meditation - user's current meditation level
// blink - user's current blink level
// wave - shows wave data
// eeg - showing eeg data
func NewNeuroskyDriver(a *NeuroskyAdaptor, name string) *NeuroskyDriver {
n := &NeuroskyDriver{
name: name,
connection: a,
Eventer: gobot.NewEventer(),
}
n.AddEvent("extended")
n.AddEvent("signal")
n.AddEvent("attention")
n.AddEvent("meditation")
n.AddEvent("blink")
n.AddEvent("wave")
n.AddEvent("eeg")
n.AddEvent("error")
return n
}
func (n *NeuroskyDriver) Connection() gobot.Connection { return n.connection }
func (n *NeuroskyDriver) Name() string { return n.name }
// adaptor returns neurosky adaptor
func (n *NeuroskyDriver) adaptor() *NeuroskyAdaptor {
return n.Connection().(*NeuroskyAdaptor)
}
// Start creates a go routine to listen from serial port
// and parse buffer readings
func (n *NeuroskyDriver) Start() (errs []error) {
go func() {
for {
buff := make([]byte, 1024)
_, err := n.adaptor().sp.Read(buff[:])
if err != nil {
n.Publish(n.Event("error"), err)
} else {
n.parse(bytes.NewBuffer(buff))
}
}
}()
return
}
// Halt stops neurosky driver (void)
func (n *NeuroskyDriver) Halt() (errs []error) { return }
// parse converts bytes buffer into packets until no more data is present
func (n *NeuroskyDriver) parse(buf *bytes.Buffer) {
for buf.Len() > 2 {
b1, _ := buf.ReadByte()
b2, _ := buf.ReadByte()
if b1 == BTSync && b2 == BTSync {
length, _ := buf.ReadByte()
payload := make([]byte, length)
buf.Read(payload)
//checksum, _ := buf.ReadByte()
buf.Next(1)
n.parsePacket(bytes.NewBuffer(payload))
}
}
}
// parsePacket publishes event according to data parsed
func (n *NeuroskyDriver) parsePacket(buf *bytes.Buffer) {
for buf.Len() > 0 {
b, _ := buf.ReadByte()
switch b {
case CodeEx:
n.Publish(n.Event("extended"), nil)
case CodeSignalQuality:
ret, _ := buf.ReadByte()
n.Publish(n.Event("signal"), ret)
case CodeAttention:
ret, _ := buf.ReadByte()
n.Publish(n.Event("attention"), ret)
case CodeMeditation:
ret, _ := buf.ReadByte()
n.Publish(n.Event("meditation"), ret)
case CodeBlink:
ret, _ := buf.ReadByte()
n.Publish(n.Event("blink"), ret)
case CodeWave:
buf.Next(1)
var ret = make([]byte, 2)
buf.Read(ret)
n.Publish(n.Event("wave"), int16(ret[0])<<8|int16(ret[1]))
case CodeAsicEEG:
ret := make([]byte, 25)
i, _ := buf.Read(ret)
if i == 25 {
n.Publish(n.Event("eeg"), n.parseEEG(ret))
}
}
}
}
// parseEEG returns data converted into EEG map
func (n *NeuroskyDriver) parseEEG(data []byte) EEG {
return EEG{
Delta: n.parse3ByteInteger(data[0:3]),
Theta: n.parse3ByteInteger(data[3:6]),
LoAlpha: n.parse3ByteInteger(data[6:9]),
HiAlpha: n.parse3ByteInteger(data[9:12]),
LoBeta: n.parse3ByteInteger(data[12:15]),
HiBeta: n.parse3ByteInteger(data[15:18]),
LoGamma: n.parse3ByteInteger(data[18:21]),
MidGamma: n.parse3ByteInteger(data[21:25]),
}
}
func (n *NeuroskyDriver) parse3ByteInteger(data []byte) int {
return ((int(data[0]) << 16) |
(((1 << 16) - 1) & (int(data[1]) << 8)) |
(((1 << 8) - 1) & int(data[2])))
}