"""
pylibftdi - python wrapper for libftdi
Copyright (c) 2010-2014 Ben Bass <benbass@codedstructure.net>
See LICENSE file for details and (absence of) warranty
pylibftdi: https://github.com/codedstructure/pylibftdi
"""
from ctypes import byref, c_uint16
from pylibftdi.device import Device
CTS_MASK = 1 << 4
DSR_MASK = 1 << 5
RI_MASK = 1 << 6
[docs]class SerialDevice(Device):
"""
simple subclass to support serial(rs232) lines
cts, dsr, ri - input
dtr, rts - output
modem_status - return a two byte bitfield of various values
Note: These lines are all active-low by default, though this can be
changed in the EEPROM settings. pylibftdi does not attempt to hide
these settings, and simply writes out the given values (i.e. '1'
will typically make an output line 'active' - and therefore low)
"""
_dtr = None
_rts = None
@property
def dtr(self):
"""
set (or get the previous set) state of the DTR line
:return: the state of the DTR line; None if not previously set
"""
return self._dtr
@dtr.setter
def dtr(self, value):
value &= 1
if value != self._dtr:
self.ftdi_fn.ftdi_setdtr(value)
self._dtr = value
@property
def rts(self):
"""
set (or get the previous set) state of the RTS line
:return: the state of the RTS line; None if not previously set
"""
return self._rts
@rts.setter
def rts(self, value):
value &= 1
if value != self._rts:
self.ftdi_fn.ftdi_setrts(value)
self._rts = value
@property
def modem_status(self):
"""
Layout of the first byte:
B0..B3 - must be 0
B4 Clear to send (CTS) 0 = inactive 1 = active
B5 Data set ready (DTS) 0 = inactive 1 = active
B6 Ring indicator (RI) 0 = inactive 1 = active
B7 Receive line signal detect (RLSD) 0 = inactive 1 = active
Layout of the second byte:
B0 Data ready (DR)
B1 Overrun error (OE)
B2 Parity error (PE)
B3 Framing error (FE)
B4 Break interrupt (BI)
B5 Transmitter holding register (THRE)
B6 Transmitter empty (TEMT)
B7 Error in RCVR FIFO
'{:016b}'.format(d.modem_status)
'0110000000000001'
- b5,b6 set in MSB ('2nd byte'), b0 set in first byte
(despite the libftdi docs saying this shouldn't be set)
"""
status = c_uint16()
self.ftdi_fn.ftdi_poll_modem_status(byref(status))
return status.value
@property
def cts(self):
"""
get the state of CTS (1 = 'active')
"""
return int(bool(self.modem_status & CTS_MASK))
@property
def dsr(self):
"""
get the state of DSR (1 = 'active')
"""
return int(bool(self.modem_status & DSR_MASK))
@property
def ri(self):
"""
get the state of RI (1 = 'active')
"""
return int(bool(self.modem_status & RI_MASK))