gistfile1.py

# Continuously read the serial port and process IO data received from a remote XBee.

from xbee import ZigBee
import serial
import struct
from array import array
import boto
import boto.s3
from datetime import datetime, date, time
import sys
from boto.s3.key import Key

AWS_ACCESS_KEY_ID = <your access key here>
bucketName = AWS_ACCESS_KEY_ID.lower() + '-farmcam-bucket'
conn = boto.connect_s3()
bucket = conn.lookup(bucketName)
if bucket is None:
  bucket = conn.create_bucket(bucketName, location=boto.s3.connection.Location.APSoutheast2)

def ByteToHex(byteStr): 
	# Convert a byte string to it's hex string representation e.g. for output.
	return ''.join( [ "%02X" % ord( x ) for x in byteStr ] ).strip() 

def percent_cb(complete, total):
	sys.stdout.write('.')
	sys.stdout.flush()

ser = serial.Serial('/dev/tty.usbserial-A901JYV9', 57600)
xbee = ZigBee(ser, escaped=True)
imageBytes = array('B')
byteCount = 0

# Continuously read and print packets
print 'Continuously read and print packets'
while True:
	try:
		response = xbee.wait_read_frame()
		msgType = struct.unpack("B", response['rf_data'][0])[0]
		if msgType == 0xf3:
			print 'info received from ' + ByteToHex(response['source_addr_long']) + ': ' + response['rf_data'][1:]
		elif msgType == 0xf4:
			bytesRemaining = struct.unpack("H", response['rf_data'][1:3][::-1])[0]
			numberOfBytesRxd = struct.unpack("B", response['rf_data'][3])[0]
			byteCount += numberOfBytesRxd
			for i in range(numberOfBytesRxd):
				imageBytes.append(struct.unpack("B", response['rf_data'][4+i])[0])
			if bytesRemaining <= 0:
				# Write the image to a file
				dt = datetime.now()
				fileName = ByteToHex(response['source_addr_long']) + '-' + dt.strftime("%Y-%m-%d-%H-%M-%S-%f") + '.jpg'
				output_file = open('../' + fileName, 'wb')
				imageBytes.tofile(output_file)
				output_file.close()
				# Write the file to S3
				print 'Uploading %s to Amazon S3 bucket %s' % (fileName, bucketName)
				k = Key(bucket)
				k.key = fileName
				k.set_contents_from_filename('../' + fileName, cb=percent_cb, num_cb=10)
				# reset for the next one
				imageBytes = array('B')
				byteCount = 0
		else:
			print 'not a recognised message type.'
	except KeyboardInterrupt:
		break

ser.close()