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Tweak the ADC classes to make the docs neater and more accurate

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This commit is contained in:
Andrew Scheller
2016-04-14 23:57:11 +01:00
parent c60d2c2bbd
commit a1ec9c67e5
5 changed files with 203 additions and 92 deletions
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81
gpiozero/spi_devices.py
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@@ -92,7 +92,7 @@ class AnalogInputDevice(SPIDevice):
def value(self):
"""
The current value read from the device, scaled to a value between 0 and
1 (or -1 to +1 for devices operating in differential mode).
1.
"""
return self._read() / (2**self.bits - 1)
@@ -119,8 +119,9 @@ class MCP3xxx(AnalogInputDevice):
def channel(self):
"""
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 1 channel.
(0-7), while the MCP3004/3204/3302 have 4 channels (0-3), the
MCP3002/3202 have 2 channels (0-1), and the MCP3001/3201/3301 only
have 1 channel.
"""
return self._channel
@@ -164,6 +165,26 @@ class MCP3xxx(AnalogInputDevice):
return ((data[1] & 63) << (self.bits - 6)) | (data[2] >> (14 - self.bits))
class MCP30xx(MCP3xxx):
"""
Extends :class:`MCP3xxx` to implement an interface for all ADC
chips with a protocol similar to the Microchip MCP30xx series of devices.
"""
def __init__(self, channel=0, differential=False, **spi_args):
super(MCP30xx, self).__init__(channel, 10, differential, **spi_args)
class MCP32xx(MCP3xxx):
"""
Extends :class:`MCP3xxx` to implement an interface for all ADC
chips with a protocol similar to the Microchip MCP32xx series of devices.
"""
def __init__(self, channel=0, differential=False, **spi_args):
super(MCP32xx, self).__init__(channel, 12, differential, **spi_args)
class MCP33xx(MCP3xxx):
"""
Extends :class:`MCP3xxx` with functionality specific to the MCP33xx family
@@ -213,18 +234,40 @@ class MCP33xx(MCP3xxx):
def _send(self):
return [16 + [8, 0][self.differential] + self.channel, 0, 0]
@property
def differential(self):
"""
If ``True``, the device is operated in 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).
class MCP3001(MCP3xxx):
Please refer to the device data-sheet to determine which channel is
used as the relative base value (for example, when using an
:class:`MCP3304` in differential mode, channel 0 is read relative to
channel 1).
"""
return super(MCP33xx, self).differential
@property
def value(self):
"""
The current value read from the device, scaled to a value between 0 and
1 (or -1 to +1 for devices operating in differential mode).
"""
return super(MCP33xx, self).value
class MCP3001(MCP30xx):
"""
The `MCP3001`_ is a 10-bit analog to digital converter with 1 channel
.. _MCP3001: http://www.farnell.com/datasheets/630400.pdf
"""
def __init__(self, **spi_args):
super(MCP3001, self).__init__(0, 10, differential=True, **spi_args)
super(MCP3001, self).__init__(0, differential=True, **spi_args)
class MCP3002(MCP3xxx):
class MCP3002(MCP30xx):
"""
The `MCP3002`_ is a 10-bit analog to digital converter with 2 channels
(0-1).
@@ -234,10 +277,10 @@ class MCP3002(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 2:
raise InputDeviceError('channel must be 0 or 1')
super(MCP3002, self).__init__(channel, 10, differential, **spi_args)
super(MCP3002, self).__init__(channel, differential, **spi_args)
class MCP3004(MCP3xxx):
class MCP3004(MCP30xx):
"""
The `MCP3004`_ is a 10-bit analog to digital converter with 4 channels
(0-3).
@@ -247,10 +290,10 @@ class MCP3004(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 4:
raise InputDeviceError('channel must be between 0 and 3')
super(MCP3004, self).__init__(channel, 10, differential, **spi_args)
super(MCP3004, self).__init__(channel, differential, **spi_args)
class MCP3008(MCP3xxx):
class MCP3008(MCP30xx):
"""
The `MCP3008`_ is a 10-bit analog to digital converter with 8 channels
(0-7).
@@ -260,20 +303,20 @@ class MCP3008(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 8:
raise InputDeviceError('channel must be between 0 and 7')
super(MCP3008, self).__init__(channel, 10, differential, **spi_args)
super(MCP3008, self).__init__(channel, differential, **spi_args)
class MCP3201(MCP3xxx):
class MCP3201(MCP32xx):
"""
The `MCP3201`_ is a 12-bit analog to digital converter with 1 channel
.. _MCP3201: http://www.farnell.com/datasheets/1669366.pdf
"""
def __init__(self, **spi_args):
super(MCP3201, self).__init__(0, 12, differential=True, **spi_args)
super(MCP3201, self).__init__(0, differential=True, **spi_args)
class MCP3202(MCP3xxx):
class MCP3202(MCP32xx):
"""
The `MCP3202`_ is a 12-bit analog to digital converter with 2 channels
(0-1).
@@ -283,10 +326,10 @@ class MCP3202(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 2:
raise InputDeviceError('channel must be 0 or 1')
super(MCP3202, self).__init__(channel, 12, differential, **spi_args)
super(MCP3202, self).__init__(channel, differential, **spi_args)
class MCP3204(MCP3xxx):
class MCP3204(MCP32xx):
"""
The `MCP3204`_ is a 12-bit analog to digital converter with 4 channels
(0-3).
@@ -296,10 +339,10 @@ class MCP3204(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 4:
raise InputDeviceError('channel must be between 0 and 3')
super(MCP3204, self).__init__(channel, 12, differential, **spi_args)
super(MCP3204, self).__init__(channel, differential, **spi_args)
class MCP3208(MCP3xxx):
class MCP3208(MCP32xx):
"""
The `MCP3208`_ is a 12-bit analog to digital converter with 8 channels
(0-7).
@@ -309,7 +352,7 @@ class MCP3208(MCP3xxx):
def __init__(self, channel=0, differential=False, **spi_args):
if not 0 <= channel < 8:
raise InputDeviceError('channel must be between 0 and 7')
super(MCP3208, self).__init__(channel, 12, differential, **spi_args)
super(MCP3208, self).__init__(channel, differential, **spi_args)
class MCP3301(MCP33xx):