server.py

#!/usr/bin/python

# Python-based HTTP server for requesting sensor data
#
# To run:
#   python server.py [port]
# where port defaults to 8080.
#
# Connect to the server via HTTP to receive latest images in JSON
# format. For example, http://127.0.0.1:8080
# Note:  Chrome seems to work better than MS IE.

# Requires:
# FTDI D2XX driver for your OS (http://www.ftdichip.com/Drivers/D2XX.htm)
# PyWin32 on Windows
#
# Tested with Python 2.7, 3.4 on Windows (32-bit), Mac OS X (10.10),
# and Ubuntu Linux 15.04.
#
# On Mac OS X, make sure the USB serial driver is unloaded. For
# example:
#
#   sudo kextunload /System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBFTDI.kext/
#
# On Linux, make sure the ftdi_sio and usbserial modules are unloaded:
#
#   sudo rmmod ftdi_sio
#   sudo rmmod usbserial
#
# Also, make sure you have permission to write to the USB device:
#
#  lsusb -d 0403:6010 -> get bus and device number
#  sudo chmod ugo+rw /dev/bus/usb/<bus number>/<device number>

# This web server is single threaded because the Sensor class is not
# thread-safe. You can serve multiple clients from it, but not at high
# speeds. If you want to use multiple clients, spawn a worker thread
# that polls the Sensor for more images, then share those images with
# the other threads.
#
# Also, the server only returns the *last* image. This is because the
# web browser demo code can't handle more than 10-20 frames per
# second. However, the sensor class itself can deliver data at 80 Hz
# or more if the downstream code is consuming it fast enough.

from __future__ import print_function

import ftd2xx as FT

import sys

from time import sleep

try:
    import BaseHTTPServer as httpServer
except:
    import http.server as httpServer

print("TESTING")

crcTable = [
  0x0000,0x1021,0x2042,0x3063,0x4084,0x50A5,0x60C6,0x70E7,
  0x8108,0x9129,0xA14A,0xB16B,0xC18C,0xD1AD,0xE1CE,0xF1EF,
  0x1231,0x0210,0x3273,0x2252,0x52B5,0x4294,0x72F7,0x62D6,
  0x9339,0x8318,0xB37B,0xA35A,0xD3BD,0xC39C,0xF3FF,0xE3DE,
  0x2462,0x3443,0x0420,0x1401,0x64E6,0x74C7,0x44A4,0x5485,
  0xA56A,0xB54B,0x8528,0x9509,0xE5EE,0xF5CF,0xC5AC,0xD58D,
  0x3653,0x2672,0x1``611,0x0630,0x76D7,0x66F6,0x5695,0x46B4,
  0xB75B,0xA77A,0x9719,0x8738,0xF7DF,0xE7FE,0xD79D,0xC7BC,
  0x48C4,0x58E5,0x6886,0x78A7,0x0840,0x1861,0x2802,0x3823,
  0xC9CC,0xD9ED,0xE98E,0xF9AF,0x8948,0x9969,0xA90A,0xB92B,
  0x5AF5,0x4AD4,0x7AB7,0x6A96,0x1A71,0x0A50,0x3A33,0x2A12,
  0xDBFD,0xCBDC,0xFBBF,0xEB9E,0x9B79,0x8B58,0xBB3B,0xAB1A,
  0x6CA6,0x7C87,0x4CE4,0x5CC5,0x2C22,0x3C03,0x0C60,0x1C41,
  0xEDAE,0xFD8F,0xCDEC,0xDDCD,0xAD2A,0xBD0B,0x8D68,0x9D49,
  0x7E97,0x6EB6,0x5ED5,0x4EF4,0x3E13,0x2E32,0x1E51,0x0E70,
  0xFF9F,0xEFBE,0xDFDD,0xCFFC,0xBF1B,0xAF3A,0x9F59,0x8F78,
  0x9188,0x81A9,0xB1CA,0xA1EB,0xD10C,0xC12D,0xF14E,0xE16F,
  0x1080,0x00A1,0x30C2,0x20E3,0x5004,0x4025,0x7046,0x6067,
  0x83B9,0x9398,0xA3FB,0xB3DA,0xC33D,0xD31C,0xE37F,0xF35E,
  0x02B1,0x1290,0x22F3,0x32D2,0x4235,0x5214,0x6277,0x7256,
  0xB5EA,0xA5CB,0x95A8,0x8589,0xF56E,0xE54F,0xD52C,0xC50D,
  0x34E2,0x24C3,0x14A0,0x0481,0x7466,0x6447,0x5424,0x4405,
  0xA7DB,0xB7FA,0x8799,0x97B8,0xE75F,0xF77E,0xC71D,0xD73C,
  0x26D3,0x36F2,0x0691,0x16B0,0x6657,0x7676,0x4615,0x5634,
  0xD94C,0xC96D,0xF90E,0xE92F,0x99C8,0x89E9,0xB98A,0xA9AB,
  0x5844,0x4865,0x7806,0x6827,0x18C0,0x08E1,0x3882,0x28A3,
  0xCB7D,0xDB5C,0xEB3F,0xFB1E,0x8BF9,0x9BD8,0xABBB,0xBB9A,
  0x4A75,0x5A54,0x6A37,0x7A16,0x0AF1,0x1AD0,0x2AB3,0x3A92,
  0xFD2E,0xED0F,0xDD6C,0xCD4D,0xBDAA,0xAD8B,0x9DE8,0x8DC9,
  0x7C26,0x6C07,0x5C64,0x4C45,0x3CA2,0x2C83,0x1CE0,0x0CC1,
  0xEF1F,0xFF3E,0xCF5D,0xDF7C,0xAF9B,0xBFBA,0x8FD9,0x9FF8,
  0x6E17,0x7E36,0x4E55,0x5E74,0x2E93,0x3EB2,0x0ED1,0x1EF0,
]

def crc16(packet):
    rem = 0
    for p in packet:
        #print("%04X %02X %04X" % (rem,p,crcTable[(rem>>8) ^ p]))
        rem = (rem << 8) ^ crcTable[(rem>>8) ^ p]
        rem = rem & 0xFFFF
    return rem

class SensorInterface(object):
    def __init__(self):
        self.sensor = None
        self.buffer = []

    def connect(self, id=None):
        """Connects to a sensor

        Use the optional id argument to specify a non-default sensor"""
        if id == None:
            id = 0;
        try:
            self.sensor = FT.open(id)
        except FT.DeviceError:
            print("Error: Device not found")
            raise

        self.sensor.setUSBParameters(8192)
        self.sensor.setLatencyTimer(2)
    def close(self):
        "Closes the connection to the sensor"
        if self.sensor:
            self.sensor.close()
        self.sensor = None

    def getAllImages(self):
        "Returns a list of all images found in the FTDI buffer"
        self.readBuffer()
        images = []
        while True:
            p = self.getPacket()
            if not p:
                return images
            if p[0] == 2: # image packet
                rows = p[14]
                cols = p[15]
                imgBuf = p[16:]
                pixels = []
                for i in range(rows):
                    pixels.append(imgBuf[(i*cols):((i+1)*cols)])
                img = { 'timeStamp' : p[5] + (p[6] << 16),
                        'sequence' : p[10],
                        'rows' : rows,
                        'cols' : cols,
                        'image' : pixels }
                images.append(img)

    def getPacket(self):
        while True:
            if len(self.buffer) == 0:
                return None

            # find BOM: 7 FFs followed by A5
            ffCount = 0
            while len(self.buffer) > 0:
                b = self.buffer.pop(0)
                if b == 0xFF:
                    ffCount += 1
                    if ffCount == 15:
                        print("Warning: Sensor buffer overflow")
                elif ffCount >= 7 and b == 0xA5:
                    break
                else:
                    ffCount == 0

            # Read length word
            if len(self.buffer) < 2:
                print("Discarded packet because buffer is empty")
                continue

            length = self.buffer[1] + (self.buffer[0] << 8)
            if length > len(self.buffer):
                # Allow this packet to be processed next time
                self.buffer.insert(0, 0xA5)
                for i in range(7):
                    self.buffer.insert(0, 0xFF)
                return None

            if length < 32:
                print("Discarded packet shorter than minimum (%d bytes vs 32 bytes)" % (length))
                continue # packet is shorter than minimum size

            packet = self.buffer[0:length]

            calcCrc = crc16(packet[4:])
            txCrc = packet[3] + (packet[2] << 8)
            if calcCrc != txCrc:
                print("Warning: Transmitted CRC %04X != %04X Calculated" % (txCrc, calcCrc))
                continue
            packet = self.removeEscapedFFs(packet)

            # convert packet to words from bytes
            lo = packet[5::2]
            hi = packet[4::2]
            packet = [lo[i] + (hi[i] << 8) for i in range(len(lo))]

            # accept the packet, remove it from buffer
            self.buffer[0:length] = []
            # print("Accepting packet, %d bytes long" % length)
            return packet

    def removeEscapedFFs(self, packet):
        # packets have 00 bytes inserted after each 4 FFs because
        # strings of FFs are used by hardware for signaling purposes
        i = 4
        while i < len(packet)-4:
            if packet[i] != 0xFF or packet[i+1] != 0xFF or packet[i+2] != 0xFF or packet[i+3] != 0xFF:
                i += 1
                continue
            print(packet[i+4])
            if packet[i+4] != 0:
                print("Warning, saw incorrect escape in FF sequence: %d" % packet[i+4])
            del packet[i+4]
            i += 1
        return packet

    def readBuffer(self):
        if not self.sensor:
            return
        # flush out buffer so we don't get old images
        rx = 65536
        while rx == 65536:
            (rx, tx, stat) = self.sensor.getStatus()
            buf = self.sensor.read(rx)
            # print("Read %d bytes" % len(buf))
            if rx == 65536:
                print("Discarding buffer...")

        if sys.version_info[0] < 3:
            buf = [ord(x) for x in buf]
        self.buffer.extend(buf)

class MyHttpHandler(httpServer.BaseHTTPRequestHandler):
    def imageToJSON(self, image):
        # JSON requires double-quotes around dict keys, Python's standard
        # __str__ gives single-quotes. Also it annotates long integers. So
        # here's a method to create actual JSON.
        self.writeStr("{")
        keys = list(image.keys())
        for j in range(len(keys)):
            k = keys[j]
            self.writeStr('"%s":%s' % (k, image[k]))
            if j != len(keys)-1:
                self.writeStr(",")
        self.writeStr("}")

    def writeStr(self, s):
        self.wfile.write(s.encode("utf-8"))

    def send_sensorData(self):
        global sensor
        self.send_response(200)
        self.send_header("Content-type", "application/json")
        self.end_headers()
        images = sensor.getAllImages()
        if len(images) > 0:
            self.imageToJSON(images[-1])
        else:
            print("Warning: no image available")
            self.writeStr("{}")

    def send_file(self, file):
        f = open(file)
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()
        for line in f:
            self.writeStr(line)
        f.close()

    def do_GET(self):
        files = ['index.html', 'jquery-1.9.1.min.js']
        if self.path == '/':
            self.path = '/index.html'

        if self.path == '/sensorData':
            self.send_sensorData()
        elif self.path[1:] in files:
            self.send_file(self.path[1:])
        else:
            self.send_response(404)
            self.send_header("Content-type", "text/html")
            self.end_headers()
            self.writeStr("<html><head><title>Not Found</title></head>")
            self.writeStr("<body><h1>Not Found</h1></body></html>")

def Main(port):
    global sensor
    sensor = SensorInterface()
    try:
        sensor.connect()
    except:
        print("Error connecting to sensor")
        raise
        return

    server = httpServer.HTTPServer(('', port), MyHttpHandler)

    try:
        server.serve_forever()
    except KeyboardInterrupt:
        pass

    sensor.close()

def Legit_Main():
    global sensor
    sensor = SensorInterface()
    try:
        sensor.connect()
    except:
        print("Error connecting to sensor")
        raise
        return

    while True:
        try:
            images = sensor.getAllImages()
            for image in images:
                print(image['timeStamp'] / 1000000) 
        except KeyboardInterrupt:
            break

    sensor.close()

runningWeb = False

if __name__ == '__main__':
    if runningWeb:
        port = 8080
        if len(sys.argv) > 1:
            port = int(sys.argv[1])
        print("running server on port " + str(port))
        Main(port)
    else:
        Legit_Main()