MAX11635 Class Reference

Driver for the on-board MAX11635 12-bit ADC (U5). More...

Public Member Functions
	averaging (self)
	Conversions the chip averages for each result: 1, 4, 8, 16 or 32.
	set_averaging (self, samples)
	Sets how many conversions the chip averages for each result.
	read (self, channel)
	Runs one conversion (averaged if set with set_averaging()).
	scan (self, last_channel=3)
	Converts channels 0 to last_channel in one scan, a few us apart.
	read_differential (self, pair=0, bipolar=True)
	True differential conversion, both inputs sampled at the same instant.

Static Public Attributes
int	CHANNELS = 4
	Number of input channels (AIN0-AIN3).
int	VBUS_CHANNEL = 3
	Channel that measures VBUS (through the 100 kOhm / 10.2 kOhm divider).

Detailed Description

Driver for the on-board MAX11635 12-bit ADC (U5).

Channels 0-2 are A3-A5; channel 3 measures VBUS through a divider. Most programs use analog_read() and the other analog functions instead; use external_adc() to get the board's instance rather than making another.

SPI bus configuration: SPI0 at 4 MHz, mode 0 (SCK GPIO22, MOSI GPIO23, MISO GPIO20, CS GPIO21), CNVST GPIO18, EOC GPIO19.

External 2.048 V reference, conversions started by CNVST (clock mode 00). Making the object resets the chip.

Member Function Documentation

set_averaging()

set_averaging	(		self,
			samples )

Sets how many conversions the chip averages for each result.

Parameters

samples

1 (off), 4, 8, 16 or 32; other values use the next lower one (values below 1 use 1).

Returns

The setting used.

read()

read	(		self,
			channel )

Runs one conversion (averaged if set with set_averaging()).

Parameters

channel

Input 0-3 (0-2 are A3-A5, 3 is VBUS).

Returns

0-4095 (0 V to 2.048 V).

Exceptions

ValueError	The channel is not 0-3.
OSError	The chip did not respond.

scan()

scan	(		self,
			last_channel = 3 )

Converts channels 0 to last_channel in one scan, a few us apart.

Parameters

last_channel

Highest channel, 0-3.

Returns

A list of last_channel + 1 codes, 0-4095.

Exceptions

ValueError	last_channel is not 0-3.
OSError	The chip did not respond.

read_differential()

read_differential	(		self,
			pair = 0,
			bipolar = True )

True differential conversion, both inputs sampled at the same instant.

Pair 0 is AIN0 - AIN1 (A3 - A4); pair 1 is AIN2 - AIN3 (A5 - VBUS monitor). The pair is set back to single-ended afterwards.

Parameters

pair	0 or 1.
bipolar	True: -2048 to 2047 (-1.024 V to +1.024 V, 0.5 mV steps). False: 0 to 4095 (0 V to 2.048 V; a negative difference reads 0).

Returns

The code.

Exceptions

ValueError	The pair is not 0 or 1.
OSError	The chip did not respond.

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The documentation for this class was generated from the following file:

• phyduino.py