mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-10-29 17:50:37 +00:00
Merge pull request #151 from waveform80/mcp-chips
Tidying up bits for #150
This commit is contained in:
Dave Jones
@@ -508,14 +508,13 @@ class AnalogInputDevice(CompositeDevice):
|
||||
Represents an analog input device connected to SPI (serial interface).
|
||||
"""
|
||||
|
||||
def __init__(self, device=0, bits=None, mode=1):
|
||||
def __init__(self, device=0, bits=None):
|
||||
if bits is None:
|
||||
raise InputDeviceError('you must specify the bit resolution of the device')
|
||||
if device not in (0, 1):
|
||||
raise InputDeviceError('device must be 0 or 1')
|
||||
self._device = device
|
||||
self._bits = bits
|
||||
self._mode = mode
|
||||
self._spi = SpiDev()
|
||||
self._spi.open(0, self.device)
|
||||
super(AnalogInputDevice, self).__init__()
|
||||
@@ -530,6 +529,13 @@ class AnalogInputDevice(CompositeDevice):
|
||||
s.close()
|
||||
super(AnalogInputDevice, self).close()
|
||||
|
||||
@property
|
||||
def bits(self):
|
||||
"""
|
||||
The bit-resolution of the device/channel.
|
||||
"""
|
||||
return self._bits
|
||||
|
||||
@property
|
||||
def bus(self):
|
||||
"""
|
||||
@@ -552,67 +558,47 @@ class AnalogInputDevice(CompositeDevice):
|
||||
@property
|
||||
def value(self):
|
||||
"""
|
||||
The relative floating point value between 0 and 1
|
||||
(scaled according to the number of bits supported bythe device).
|
||||
The current value read from the device, scaled to a value between 0 and
|
||||
1.
|
||||
"""
|
||||
return self._read() / (2**self._bits - 1)
|
||||
return self._read() / (2**self.bits - 1)
|
||||
|
||||
@property
|
||||
def relVal(self):
|
||||
def raw_value(self):
|
||||
"""
|
||||
The relative floating point value between 0 and 1
|
||||
(scaled according to the number of bits supported bythe device).
|
||||
"""
|
||||
return self._read() / ((2**self._bits) - 1)
|
||||
|
||||
@property
|
||||
def absVal(self):
|
||||
"""
|
||||
The absolute value as read from the device
|
||||
The raw value as read from the device.
|
||||
"""
|
||||
return self._read()
|
||||
|
||||
@property
|
||||
def mode(self):
|
||||
"""
|
||||
The device mode: single ended (1) or diferential (0)
|
||||
"""
|
||||
return self._mode()
|
||||
|
||||
|
||||
|
||||
class MCP3xxx(AnalogInputDevice):
|
||||
def __init__(self, channel=0, device=0, bits=10, mode=1): #default values
|
||||
if mode not in (0, 1):
|
||||
raise InputDeviceError('Mode must be 1 or 0')
|
||||
def __init__(self, channel=0, device=0, bits=10, differential=False):
|
||||
self._channel = channel
|
||||
self._bits = bits
|
||||
self._mode = mode
|
||||
super(MCP3xxx, self).__init__(device=device, bits=bits, mode=mode)
|
||||
|
||||
self._differential = bool(differential)
|
||||
super(MCP3xxx, self).__init__(device, bits)
|
||||
|
||||
@property
|
||||
def channel(self):
|
||||
"""
|
||||
The channel to read data from. The MCP3008/3208/3304 have 8 channels (so this will
|
||||
be between 0 and 7) while the MCP3004/3204/3302 have 4 channels (range 0 to 3)and
|
||||
the MCP3301 only has 2 channels.
|
||||
The channel to read data from. The MCP3008/3208/3304 have 8 channels
|
||||
(0-7), while the MCP3004/3204/3302 have 4 channels (0-3), and the
|
||||
MCP3301 only has 2 channels.
|
||||
"""
|
||||
return self._channel
|
||||
|
||||
@property
|
||||
def bits(self):
|
||||
def differential(self):
|
||||
"""
|
||||
The bit-resolution of the device/channel.
|
||||
"""
|
||||
return self._bits
|
||||
If True, the device is operated in pseudo-differential mode. In this
|
||||
mode one channel (specified by the channel attribute) is read relative
|
||||
to the value of a second channel (implied by the chip's design).
|
||||
|
||||
@property
|
||||
def mode(self):
|
||||
Please refer to the device data-sheet to determine which channel is
|
||||
used as the relative base value (for example, when using an MCP3008
|
||||
in differential mode, channel 0 is read relative to channel 1).
|
||||
"""
|
||||
The device mode: single ended (1) or diferential (0)
|
||||
"""
|
||||
return self._mode
|
||||
|
||||
return self._differential
|
||||
|
||||
def _read(self):
|
||||
# MCP3008/04 or MCP3208/04 protocol looks like the following:
|
||||
@@ -622,119 +608,142 @@ class MCP3xxx(AnalogInputDevice):
|
||||
# Tx 0001MCCC xxxxxxxx xxxxxxxx
|
||||
# Rx xxxxxxxx x0RRRRRR RRRRxxxx for the 3004/08
|
||||
# Rx xxxxxxxx x0RRRRRR RRRRRRxx for the 3204/08
|
||||
# Rx xxxxxxxx xx0RRRRR RRRRRRRR for the 3301/02/04
|
||||
#
|
||||
# The transmit bits start with 3 preamble bits "000" (to warm up),
|
||||
# a start bit "1" followed by the mode bit(M) which is 1 for
|
||||
# single-ended read, and 0 for differential read,
|
||||
# followed by 3-bits for the channel (C).
|
||||
# The remainder of the transmission are "don't care" bits (x).
|
||||
# The transmit bits start with 3 preamble bits "000" (to warm up), a
|
||||
# start bit "1" followed by the mode bit(M) which is 1 for single-ended
|
||||
# read, and 0 for differential read, followed by 3-bits for the channel
|
||||
# (C). The remainder of the transmission are "don't care" bits (x).
|
||||
#
|
||||
# The first byte received and the top 1 bit of the second byte are
|
||||
# don't care bits (x). These are followed by a null bit (0), and then
|
||||
# the result bits (R). 10 bits for the MCP300x, 12 bits for the MCP320x
|
||||
# and 13 bits for the MCP330x
|
||||
# Warning: The mode bit is a new implimentation and needs to be tested.
|
||||
|
||||
if self.mode:
|
||||
tx = 24 # '00011000' S bit 1 and M bit 1
|
||||
else:
|
||||
tx = 16 # '00010000' S bit 1 and M bit 0
|
||||
data = self._spi.xfer2([(tx + self.channel), 0, 0])
|
||||
if self.bits == 13:
|
||||
val = ((data[1] & 31) << (self.bits-5)) | (data[2] )
|
||||
else:
|
||||
val = ((data[1] & 63) << (self.bits-6)) | (data[2] >> (14 - self.bits))
|
||||
return (val)
|
||||
# the result bits (R). 10 bits for the MCP300x, 12 bits for the
|
||||
# MCP320x.
|
||||
#
|
||||
# XXX Differential mode still requires testing
|
||||
data = self._spi.xfer2([16 + [8, 0][self.differential] + self.channel, 0, 0])
|
||||
return ((data[1] & 63) << (self.bits - 6)) | (data[2] >> (14 - self.bits))
|
||||
|
||||
|
||||
class MCP33xx(MCP3xxx):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
super(MCP33xx, self).__init__(channel, device, 12, differential)
|
||||
|
||||
def _read(self):
|
||||
# MCP3308/04 protocol looks like the following:
|
||||
#
|
||||
# Byte 0 1 2
|
||||
# ==== ======== ======== ========
|
||||
# Tx 0001MCCC xxxxxxxx xxxxxxxx
|
||||
# Rx xxxxxxxx x0SRRRRR RRRRRRRx
|
||||
#
|
||||
# The transmit bits start with 3 preamble bits "000" (to warm up), a
|
||||
# start bit "1" followed by the mode bit(M) which is 1 for single-ended
|
||||
# read, and 0 for differential read, followed by 3-bits for the channel
|
||||
# (C). The remainder of the transmission are "don't care" bits (x).
|
||||
#
|
||||
# The first byte received and the top 1 bit of the second byte are
|
||||
# don't care bits (x). These are followed by a null bit (0), then the
|
||||
# sign bit (S), and then the 12 result bits (R).
|
||||
#
|
||||
# In single read mode (the default) the sign bit is always zero and the
|
||||
# result is effectively 12-bits. In differential mode, the sign bit is
|
||||
# significant and the result is a two's-complement 13-bit value.
|
||||
#
|
||||
# The MCP3301 variant of the chip always operates in differential
|
||||
# mode and effectively only has one channel (composed of an IN+ and
|
||||
# IN-). As such it requires no input, just output. This is the reason
|
||||
# we split out _send() below; so that MCP3301 can override it.
|
||||
data = self._spi.xfer2(self._send())
|
||||
# Extract the last two bytes (again, for MCP3301)
|
||||
data = data[-2:]
|
||||
result = ((data[0] & 63) << 7) | (data[1] >> 1)
|
||||
# Account for the sign bit
|
||||
if self.differential and value > 4095:
|
||||
result = -(8192 - result)
|
||||
assert -4096 <= result < 4096
|
||||
return result
|
||||
|
||||
def _send(self):
|
||||
return [16 + [8, 0][self.differential] + self.channel, 0, 0]
|
||||
|
||||
|
||||
class MCP3004(MCP3xxx):
|
||||
"""
|
||||
The MCP3004 is a 10 bit Analog to Digital Converter with
|
||||
4 channels single ended or 2 channels diferential.
|
||||
The channel number must be 0, 1, 2 or 3
|
||||
The MCP3004 is a 10-bit analog to digital converter with 4 channels (0-3).
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 4:
|
||||
raise InputDeviceError('channel must be between 0 and 3')
|
||||
super(MCP3004, self).__init__(channel, device, bits=10, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3004, self).__init__(channel, device, 10, differential)
|
||||
|
||||
|
||||
class MCP3008(MCP3xxx):
|
||||
"""
|
||||
The MCP3208 is a 10 bit Analog to Digital Converter with
|
||||
8 channels single ended or 4 channels diferential.
|
||||
The channel number must be 0, 1, 2, 3, 4, 5, 6, 7 or 8
|
||||
The MCP3008 is a 10-bit analog to digital converter with 8 channels (0-7).
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 8:
|
||||
raise InputDeviceError('channel must be between 0 and 7')
|
||||
super(MCP3008, self).__init__(device=device, bits=10, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3008, self).__init__(channel, device, 10, differential)
|
||||
|
||||
|
||||
class MCP3204(MCP3xxx):
|
||||
"""
|
||||
The MCP3204 is a 10 bit Analog to Digital Converter with
|
||||
4 channels single ended or 2 channels diferential.
|
||||
The channel number must be 0, 1, 2 or 3
|
||||
The MCP3204 is a 12-bit analog to digital converter with 4 channels (0-3).
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 4:
|
||||
raise InputDeviceError('channel must be between 0 and 3')
|
||||
super(MCP3204, self).__init__(channel, device, bits=12, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3204, self).__init__(channel, device, 12, differential)
|
||||
|
||||
|
||||
class MCP3208(MCP3xxx):
|
||||
"""
|
||||
The MCP3208 is a 13 bit Analog to Digital Converter with
|
||||
8 channels single ended or 4 channels diferential.
|
||||
The channel number must be 0, 1, 2, 3, 4, 5, 6, 7 or 8
|
||||
The MCP3208 is a 12-bit analog to digital converter with 8 channels (0-7).
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 8:
|
||||
raise InputDeviceError('channel must be between 0 and 7')
|
||||
super(MCP3208, self).__init__(device=device, bits=12, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3208, self).__init__(channel, device, 12, differential)
|
||||
|
||||
class MCP3301(MCP3xxx):
|
||||
"""
|
||||
The MCP3301 is a 13 bit Analog to Digital Converter with
|
||||
2 channels single ended or 1 channel diferential.
|
||||
The channel number must be 0, or 1
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
if not 0 <= channel < 2:
|
||||
raise InputDeviceError('channel must be between 0 and 1')
|
||||
super(MCP3301, self).__init__(device=device, bits=13, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
|
||||
class MCP3302(MCP3xxx):
|
||||
class MCP3301(MCP33xx):
|
||||
"""
|
||||
The MCP3302 is a 13 bit Analog to Digital Converter with
|
||||
4 channels single ended or 2 channels diferential.
|
||||
The channel number must be 0, 1, 2 or 3
|
||||
The MCP3301 is a signed 13-bit analog to digital converter. Please note
|
||||
that the MCP3301 always operates in differential mode between its two
|
||||
channels and the output value is scaled from -1 to +1.
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, device=0):
|
||||
super(MCP3301, self).__init__(0, device, differential=True)
|
||||
|
||||
def _send(self):
|
||||
return [0, 0]
|
||||
|
||||
|
||||
class MCP3302(MCP33xx):
|
||||
"""
|
||||
The MCP3302 is a 12/13-bit analog to digital converter with 4 channels
|
||||
(0-3). When operated in differential mode, the device outputs a signed
|
||||
13-bit value which is scaled from -1 to +1. When operated in single-ended
|
||||
mode (the default), the device outputs an unsigned 12-bit value scaled from
|
||||
0 to 1.
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 4:
|
||||
raise InputDeviceError('channel must be between 0 and 4')
|
||||
super(MCP3302, self).__init__(device=device, bits=13, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3302, self).__init__(channel, device, differential)
|
||||
|
||||
class MCP3304(MCP3xxx):
|
||||
|
||||
class MCP3304(MCP33xx):
|
||||
"""
|
||||
The MCP3304 is a 13 bit Analog to Digital Converter with
|
||||
4 channels single ended or 2 channels diferential.
|
||||
The channel number must be 0, 1, 2, 3, 4, 5, 6, 7 or 8
|
||||
The MCP3304 is a 12/13-bit analog to digital converter with 8 channels
|
||||
(0-7). When operated in differential mode, the device outputs a signed
|
||||
13-bit value which is scaled from -1 to +1. When operated in single-ended
|
||||
mode (the default), the device outputs an unsigned 12-bit value scaled from
|
||||
0 to 1.
|
||||
"""
|
||||
def __init__(self, channel=0, device=0, mode=1):
|
||||
def __init__(self, channel=0, device=0, differential=False):
|
||||
if not 0 <= channel < 8:
|
||||
raise InputDeviceError('channel must be between 0 and 7')
|
||||
super(MCP3304, self).__init__(device=device, bits=13, mode=mode)
|
||||
self._channel = channel
|
||||
self._mode = mode
|
||||
super(MCP3304, self).__init__(channel, device, differential)
|
||||
|
||||
|
||||
Reference in New Issue
Block a user