retina.py

import serial
import time
import thread
import numpy as np

class Retina(object):
    def __init__(self, port='/dev/ttyUSB0', record=None):
        self.serial = serial.Serial(port, baudrate=8000000, rtscts=True)
        time.sleep(0.1)
        self.serial.write("E+\nZ+\n")
        self.image = np.zeros((128, 128), dtype=float)
        if record is not None:
            self.record = open(record, 'w')
        else:
            self.record = None
        thread.start_new_thread(self.update_loop, ())

    def clear_image(self):
        self.image *= 0.5

    def update_loop(self):
        events = 0
        while True:
            byte0 = ord(self.serial.read())
            if byte0 & 0x80 == 0:
                #print 'invalid byte', byte0, chr(byte0), 'good:', events
                continue
            byte0 = byte0 & 0x7F   # strip the top byte
            byte1 = ord(self.serial.read())
            sign = byte1 >= 0x7F
            byte1 = byte1 & 0x7F   # strip the top byte
            self.image[byte1, byte0] += 1 if sign else -1
            if self.record is not None:
                self.record.write('%d %d %d %f\n' % (byte0, byte1, sign,
                    time.time()))
            events += 1

class RetinaRecord(object):
    def __init__(self, filename):
        self.data = open(filename)
        self.image = np.zeros((128, 128), dtype=float)
        thread.start_new_thread(self.update_loop, ())

    def clear_image(self):
        self.image *= 0.5

    def update_loop(self):
        offset = None

        for line in self.data.readlines():
            x, y, sign, t = line.strip().split()
            y = int(y)
            x = int(x)
            sign = int(sign)
            t = float(t)
            if offset is None:
                offset = time.time() - t

            while time.time() < t + offset:
                time.sleep(0.001)
                pass

            self.image[y, x] += 1 if sign else -1

class RetinaView(object):
    def __init__(self, retina):
        self.retina = retina
        thread.start_new_thread(self.update_loop, ())

    def update_loop(self):
        import pylab
        pylab.ion()
        vmin, vmax = -1, 1
        self.img = pylab.imshow(self.retina.image, vmin=vmin, vmax=vmax,
                                cmap='gray', interpolation='none')
        while True:
            self.img.set_data(self.retina.image)
            self.retina.clear_image()
            pylab.draw()
            time.sleep(0.02)


if __name__ == '__main__':
    #retina = Retina(record='blinking_2.data')
    retina = RetinaRecord('blinking_2.data')
    view = RetinaView(retina)
    while True:
        time.sleep(1)