def rxpacket(ser):
payload = b''
# Header: 0x7e
header = ser.read(1)
if header != b'\x7e':
print('Error receiving packet: Header')
return 0, payload
# Length: 2 bytes
lengthb = ser.read(2)
length = int.from_bytes(lengthb, 'big')
if length == 0:
print('Error receiving packet: Zero length')
return 0, payload
# Payload
checksum = b'\x00'
payload = b''
for i in range(length):
currbyte = ser.read(1)
payload = payload + currbyte
checksum = byte_sum(checksum, currbyte)
# Checksum
currbyte = ser.read(1)
checksum = byte_diff0xff(checksum)
if checksum != currbyte:
print('Error receiving packet: Invalid checksum')
return 0, payload
print('Received XBee API frame w/ length {}'.format(length))
return 1, payload
def atcom_set(param, value):
# Header
bytestr = b'\x7e'
# Length
length = 4 + len(value)
bytestr = bytestr + (length).to_bytes(2, 'big')
# Frame type
ftype = b'\x08'
bytestr = bytestr + ftype
# Frame ID
fid = b'\x01'
bytestr = bytestr + fid
checksum = byte_sum(ftype, fid)
# AT command
athi = bytes(param[0], 'ascii')
atlo = bytes(param[1], 'ascii')
bytestr = bytestr + athi + atlo
checksum = byte_sum(checksum, athi)
checksum = byte_sum(checksum, atlo)
# Parameter value
bytestr = bytestr + value
for i in range(len(value)):
checksum = byte_sum(checksum, (value[i]).to_bytes(1, 'big'))
# Checksum
checksum = byte_diff0xff(checksum)
bytestr = bytestr + checksum
return bytestr
def atcom_query(param):
# Header
bytestr = b'\x7e'
# Length
length = 4
bytestr = bytestr + (length).to_bytes(2, 'big')
# Frame type
ftype = b'\x08'
bytestr = bytestr + ftype
# Frame ID
fid = b'\x01'
bytestr = bytestr + fid
checksum = byte_sum(ftype, fid)
# AT command
athi = bytes(param[0], 'ascii')
atlo = bytes(param[1], 'ascii')
bytestr = bytestr + athi + atlo
checksum = byte_sum(checksum, athi)
checksum = byte_sum(checksum, atlo)
# Checksum
checksum = byte_diff0xff(checksum)
bytestr = bytestr + checksum
return bytestr
def debug_unicast(n, dest):
# Header
bytestr = b'\x7e'
# Length
length = 17
bytestr = bytestr + (length).to_bytes(2, 'big')
# Frame type
ftype = b'\x10'
bytestr = bytestr + ftype
# Frame ID
fid = b'\x01'
bytestr = bytestr + fid
checksum = byte_sum(ftype, fid)
# 64-bit dest addr
bytestr = bytestr + dest
for i in range(8):
checksum = byte_sum(checksum, dest[i].to_bytes(1, 'big'))
# 16-bit dest addr
dest16 = b'\xff\xfe'
bytestr = bytestr + dest16
for i in range(2):
checksum = byte_sum(checksum, dest16[i].to_bytes(1, 'big'))
# Broadcast radius
brad = b'\x00'
bytestr = bytestr + brad
checksum = byte_sum(checksum, brad)
# Options
opt = b'\x00'
bytestr = bytestr + opt
checksum = byte_sum(checksum, opt)
# Data
data = b'DU'
if n > 255:
print('Error: number of transmissions exceeds limit')
return bytestr
data = data + (n).to_bytes(1, 'big')
bytestr = bytestr + data
checksum = byte_sum(checksum, b'D')
checksum = byte_sum(checksum, b'U')
checksum = byte_sum(checksum, (n).to_bytes(1, 'big'))
# Checksum
checksum = byte_diff0xff(checksum)
bytestr = bytestr + checksum
return bytestr
def gen_headtail(bytestr):
# Compute checksum
checksum = b'\x00'
for i in range(len(bytestr)):
checksum = byte_sum(checksum, (bytestr[i]).to_bytes(1, 'big'))
checksum = byte_diff0xff(checksum)
# Generate length
length = (len(bytestr)).to_bytes(2, 'big')
# Append headers and checksum
bytestr = b'\x7e' + length + bytestr + checksum
return bytestr
def rxpacket_buffered(ser):
success = 0
# Header(0x7e) + Length(2 bytes)
buffer = ser.read(3)
# Timeout check
if buffer == b'':
print('Serial read timeout - pd.rxpacket_buffered()')
return success, buffer
# Get entire packet
lengthb = buffer[1:3]
length = int.from_bytes(lengthb, 'big')
if length == 0:
print('Error receiving packet: Zero length')
return success, buffer
buffer_new = ser.read(length + 1)
if buffer_new == b'':
print('Serial read timeout - pd.rxpacket_buffered()')
return success, buffer
buffer = buffer + buffer_new
payload = buffer[3:-1]
# Compute payload checksum
checksum = 0
for i in range(length):
checksum = checksum + buffer[i + 3]
# overflow check
if checksum > 255:
checksum = checksum - 256
checksumb = (checksum).to_bytes(1, 'big')
checksumb = byte_diff0xff(checksumb)
if checksumb != (buffer[-1]).to_bytes(1, 'big'):
print('Error receiving packet: Invalid checksum')
return success, payload
success = 1
print('Received XBee API frame w/ length {}'.format(length))
return success, payload