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