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SPCSSerial.py
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SPCSSerial.py
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import serial
import time
from Queue import Empty
from multiprocessing import Queue, Process, Value, Array, Lock
'''
TODO
- figure out how to save parameters
Weird behavior
- When p = 14 -> Position feedback = position desired + (force damping/offset)
- when offest is present -> decreasing P increases steady state error
8 Byte Command Packet
1st Byte '$'
2nd Byte 'C'
3rd Byte Command Byte (0 - 255)
4th Byte Lower Data Byte (0 - 255)
5th Byte Upper Data Byte (0 - 255)
6th Byte '#'
7th Byte Lower CRC Byte (0 - 255)
8th Byte Upper CRC Byte (0 -255)
6 Byte Response Packet
1st Byte '+'
2nd Byte Lower Data (lower 8 bits)
3rd Byte Upeer Data (upper 8 bits)
4th Byte '#'
5th Byte Lower CRC (lower 8 bits)
6th Byte Upper CRC (upper 8 bits)
Command List
1 Set Proportional (0 to 1000)
2 Set Derivative (0 to 1000)
8 Forced Damping(0 to 1000)
15 Offset ( -1000 to 1000)
88 Set Command (0 to 4095)
89 SET_COMMAND_SOURCE (0/1)
112 *undocumented - startup command
113 *undocumented - startup command
119 *undocumented - startup command
126 *undocumented - startup command
128 *undocumented - startup command
129 *undocumented - startup command
130 *undocumented - startup command
131 *undocumented - startup command
132 *undocumented - startup command
134 *undocumented - startup command
135 *undocumented - startup command
136 *undocumented - startup command
137 *undocumented - startup command
138 *undocumented - startup command
139 *undocumented - startup command
140 *undocumented - startup command
144 *undocumented - startup command
146 *undocumented - startup command
149 *undocumented - startup command
148 *undocumented - startup command
147 Get Serial Number
152 Get Analog Set Point (returns 0 to 4095)
153 Get Feedback (returns 0 to 4095)
154 Get Pressure 1 (returns 0 to 4095)
155 Get Pressure 2 (returns 0 to 4095)
161 *undocumented - startup command
162 *undocumented - startup command
163 *undocumented - startup command
164 *undocumented - startup command
Max stream rates(hz):
set_pos = 300;
set_pos = 100; pos+pres = 33
set_pos = 100; pos = 100
set_pos = 100; pres = 50
'''
class SPCS2_USB():
def __init__(self,port,ID):
self.ID = ID
#serial config
self.ser = None
self.port = port
#controller state
self.command_source = 1
#controller feeback
self.outgoing = Queue()
self.incoming = Queue()
self._serial_number = Value('i',-1)
self._position = Value('i',-1)
self._pressure = Array('i',2)
self._pressure[0] = -1
#callbacks
self.serial_number_callback = None
self.position_callback = None
self.pressure_callback = None
self.misc_callback = None
#processes
self.IO_process = None
self.running = False
self.lock = Lock()
@property
def serial_number(self):
return self._serial_number.value
@property
def position(self):
return self._position.value
@property
def pressure(self):
return [self._pressure[0],self._pressure[1]]
def open(self,timeout = 2):
#start incoming data process
self.running = True
self.IO_process = Process(target=self.process_IO)
self.IO_process.daemon = True
self.IO_process.start()
#request serial_number
self.request_serial_number()
if timeout > 0:
start = time.time()
while self._serial_number.value == -1 and (time.time()-start) < timeout:
time.sleep(0.1)
def close(self):
self.running = False
try:
#stop process
self.IO_process.join()
#clear I/O buffers
self.ser.flushInput()
self.ser.flushOutput()
#close serial port
self.ser.close()
except AttributeError:
pass
@classmethod
# pack_command - packages a command
def pack_command(cls, command, value):
packet = bytearray(['$', #header
'C', #header
command & 0xFF, #command
value & 0xFF, #lower data
(value >> 8) & 0xFF, #upper data
'#']) #stop
crc = cls.compute_CRC(packet,6)
packet += bytearray([crc & 0xFF, #lower crc
(crc >> 8) & 0xFF]) #upper crc
return packet
@classmethod
# compute_CRC - computes CRC of packet
def compute_CRC(cls, packet, length):
crc16reg = 0xFFFF
u16Poly16 = 0xA001
u16MsgByte = 0
for j in range(0,length):
try:
u16MsgByte = 0x00FF & ord(packet[j])
except:
u16MsgByte = 0x00FF & int(packet[j])
for i in range(0,8):
if (crc16reg ^ u16MsgByte) & 0x0001:
crc16reg = (crc16reg >> 1) ^ u16Poly16
else:
crc16reg = crc16reg >> 1
u16MsgByte >>= 1
return crc16reg
@classmethod
# unpack_response - decodes a response packet from controller
def unpack_response(cls, packet):
#check for complete packet
if len(packet) < 6:
raise RuntimeError("Incomplete or empty Packet")
#check missing for header or footer
if packet[0] != '+' or packet[3] != '#':
raise RuntimeError("Misaligned data")
#extract data
data_lower = ord(packet[1])
data_upper = ord(packet[2])
data = (data_upper << 8) | (data_lower & 0x00FF)
#extract crc
crc_lower = ord(packet[4])
crc_upper = ord(packet[5])
crc_packet = (crc_upper << 8) | (crc_lower & 0x00FF)
#crc check
crc_data = cls.compute_CRC(packet,4)
if crc_data != crc_packet:
raise RuntimeError('CRC mismatch')
return data
# set_position - set the position from a PC (0 - 4095)
def set_position(self,value):
#state check
if self.command_source != 0:
raise RuntimeError("Controller not under PC control")
#parameter check
if value < 0 or value > 4095:
raise ValueError("{} is out of range(0-4095)".format(value))
#create command and queue it up
command = self.pack_command(88,value)
self.outgoing.put(command)
self.incoming.put("set_position")
# set_command_source - set the command source (0: PC, 1: Analog)
def set_command_source(self,source):
#parameter check
if source < 0 or source > 1:
raise ValueError("{} is out of range(0 or 1)".format(source))
#create command and queue it up
command = self.pack_command(89,source)
self.outgoing.put(command)
self.incoming.put("set_command_source")
self.command_source = source
# set_proportional - set the proportional gain 0-100% (0 - 1000)
def set_proportional(self,value):
#parameter check
if value < 0 or value > 1000:
raise ValueError("{} is out of range(0-1000)".format(value))
#create command and queue it up
command = self.pack_command(1,value)
self.outgoing.put(command)
self.incoming.put("set_proportional")
# set_derivative - set the derivative gain 0-100% (0 - 1000)
def set_derivative(self,value):
#parameter check
if value < 0 or value > 1000:
raise ValueError("{} is out of range(0-1000)".format(value))
#create command and queue it up
command = self.pack_command(2,value)
self.outgoing.put(command)
self.incoming.put("set_derivative")
# set_force_damping - set the force damping constant (0 - 1000)
def set_force_damping(self,value):
#parameter check
if value < 0 or value > 1000:
raise ValueError("{} is out of range(0-1000)".format(value))
#create command and queue it up
command = self.pack_command(8,value)
self.outgoing.put(command)
self.incoming.put("set_force_damping")
# set_offset- set the position offset (-1000 - 1000)
def set_offset(self,value):
#parameter check
if value < -1000 or value > 1000:
raise ValueError("{} is out of range(-1000 - 1000)".format(value))
#create command and queue it up
command = self.pack_command(15,value)
self.outgoing.put(command)
self.incoming.put("set_offset")
# request_position- get the position feedback of controller (returns 0 - 4095)
def request_position(self):
#create request and queue it up
command = self.pack_command(153,4369)
self.outgoing.put(command)
self.incoming.put("position_req")
# request_pressure - get the pressure feedback of controller (returns array[2] 0 - 4095)
def request_pressure(self):
#create request and queue it up
command = self.pack_command(154,4369)
self.outgoing.put(command)
self.incoming.put("pressure1_req")
#create request and queue it up
command = self.pack_command(155,4369)
self.outgoing.put(command)
self.incoming.put("pressure2_req")
# request_serial_number - get controller serial number
def request_serial_number(self):
#create request and queue it up
command = self.pack_command(147,4369)
self.outgoing.put(command)
self.incoming.put("serial_number_req")
def process_IO(self):
try:
self.ser = serial.Serial(port = self.port,
baudrate = 115200,
timeout = 0.5)
except OSError:
return
#clear I/O buffers
self.ser.flushInput()
self.ser.flushOutput()
time.sleep(0.3)
temp_pressure1 = None
last_write = 0
write_period = 1/1000.0
last_warning = 0
warning_period = 0.5
while self.running:
if self.outgoing.qsize() > 20 and time.time() - last_warning > warning_period:
print "{}: WARNING: WRITING too fast, queued packets = {} ".format(self.ID,self.outgoing.qsize())
last_warning = time.time()
elif self.incoming.qsize() > 20 and time.time() - last_warning > warning_period:
print "{}: WARNING: READING to slow, queued packets = {} bytes available = {}".format(self.ID,self.incoming.qsize(),self.ser.inWaiting())
last_warning = time.time()
try:
#send next available outgoing message
if time.time() - last_write > write_period:
packet = self.outgoing.get(block = False)
self.ser.write(packet)
last_write = time.time()
self.ser.flush()
except Empty:
pass
#check for a response
if self.ser.inWaiting() > 5:
#process response
raw = self.ser.read(6)
data = self.unpack_response(raw)
typ = self.incoming.get()
#serial number response
if typ == "serial_number_req":
#with self._serial_number.get_lock():
self._serial_number.value = data
if self.serial_number_callback is not None:
self.serial_number_callback(data)
#pressure1 response
elif typ == "pressure1_req":
#pressure1 should always be requested before pressure2
temp_pressure1 = data
#pressure2 response
elif typ == "pressure2_req":
#with self._pressure.get_lock():
self._pressure[0] = temp_pressure1
self._pressure[1] = data
if self.pressure_callback is not None:
self.pressure_callback([temp_pressure1,data])
#position response
elif typ == "position_req":
#with self._position.get_lock():
self._position.value = data
if self.position_callback is not None:
self.position_callback(data)
#handle all other responses
else:
if self.misc_callback is not None:
self.misc_callback(data)
else:
time.sleep(0.001)
if __name__ == "__main__":
#connect to controller
port = raw_input(">>Please enter device port: ")
controller = SPCS2_USB(port)
controller.open()
print("Connected to {} on {}".format(controller.serial_number,port))
try:
print("Available Programs:")
print(" 1. Set position + read data")
print(" 2. Sweep")
print(" 3. Set parameters")
program = int(raw_input(">>Please enter program: "))
#set position
if program == 1:
controller.set_command_source(0)
print("Enabled USB control")
while True:
value = int(raw_input(">>Please enter a piston position(0-4095): "))
controller.set_position(value)
controller.request_position()
controller.request_pressure()
time.sleep(0.25) #wait for piston to move
position = controller.position
pressure = [None,None]#controller.pressure
print("Position: {}, Pressure1: {}, Pressure2: {}".format(position,pressure[0],pressure[1]))
#Sweep
elif program == 2:
rate = 60
controller.set_command_source(0)
print("Enabled USB control")
speed = int(raw_input(">>Please enter a sweep speed: steps per 10 ms (10-600): "))
while True:
for i in range(200,3500,speed):
controller.set_position(i)
time.sleep(1.0/rate)
print "top"
for i in range(3500,200, -speed):
controller.set_position(i)
time.sleep(1.0/rate)
print "bottom"
#set parameters
elif program == 3:
print("Available parameters:")
print(" p -- proportional gain (0 - 1000) Ex: p10")
print(" d -- derivative gain (0 - 1000) Ex: d142")
print(" f -- force dampening gain (0 - 1000) Ex: f213")
print(" o -- offset (-1000 - 1000) Ex: o-267")
while True:
raw = raw_input(">>Please enter a parameter (p/d/f/o)(value): ")
param = raw[0].lower()
if param == 'p':
value = int(raw[1:])
controller.set_proportional(value)
print("Set proportional gain to {}".format(value))
elif param == 'd':
value = int(raw[1:])
controller.set_derivative(value)
print("Set derivative gain to {}".format(value))
elif param == 'f':
value = int(raw[1:])
controller.set_force_damping(value)
print("Set force dampening to {}".format(value))
elif param == 'o':
value = int(raw[1:])
controller.set_offset(value)
print("Set offset to {}".format(value))
else:
print("invalid parameter")
else:
print("invalid program number")
except KeyboardInterrupt:
print("KeyboardInterrupt")
finally:
controller.close()
print("Closed connection")