waveshare_definitions.py

from ADS1256_definitions import *

# MAK: Moved these values here to declutter other files

# For channel code values (bitmask) definitions, see ADS1256_definitions.py.
# The values representing the negative and positive input pins connected to
# the ADS1256 hardware multiplexer must be bitwise OR-ed to form eight-bit
# values, which will later be sent to the ADS1256 MUX register. The register
# can be explicitly read and set via ADS1256.mux property, but here we define
# a list of differential channels to be input to the ADS1256.read_sequence()
# method which reads all of them one after another.
#
# ==> Each channel in this context represents a differential pair of physical
# input pins of the ADS1256 input multiplexer.
#
# ==> For single-ended measurements, simply select AINCOM as the negative input.
#
# AINCOM does not have to be connected to AGND (0V), but it is if the jumper
# on the Waveshare board is set.
#
# Input pin for the potentiometer on the Waveshare Precision ADC board:
POTI = POS_AIN0|NEG_AINCOM
# Light dependant resistor of the same board:
LDR  = POS_AIN1|NEG_AINCOM
# The other external input screw terminals of the Waveshare board:
EXT2, EXT3, EXT4 = POS_AIN2|NEG_AINCOM, POS_AIN3|NEG_AINCOM, POS_AIN4|NEG_AINCOM
EXT5, EXT6, EXT7 = POS_AIN5|NEG_AINCOM, POS_AIN6|NEG_AINCOM, POS_AIN7|NEG_AINCOM

# You can connect any pin as well to the positive as to the negative ADC input.
# The following reads the voltage of the potentiometer with negative polarity.
# The ADC reading should be identical to that of the POTI channel, but negative.
POTI_INVERTED = POS_AINCOM|NEG_AIN0

# For fun, connect both ADC inputs to the same physical input pin.
# The ADC should always read a value close to zero for this.
SHORT_CIRCUIT = POS_AIN0|NEG_AIN0

# There's code with a pseudo binary search in the full_example.py, but this is a reasonable value for the min
# voltage to have the LED just in the off state. Above this value, you will start to see output.
DEFAULT_LED_BIAS = 0x7000
# The max bias/brightness might be a tiny bit lower but this is fine
MAX_BIAS = 0xffff
LED_RANGE = MAX_BIAS - DEFAULT_LED_BIAS