Getting Temperature/Humidity/Ambient Light data with Python

Getting Temperature/Humidity/Ambient Light data with Python - Printable Version

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Getting Temperature/Humidity/Ambient Light data with Python - Yomet - 09-28-2016

Hi,

I have tried to get data from both the Temp/Humidity and the Ambient Light sensor by using python and python-smbus. I have found and read the tech docs of both adapters as specified by Pine64 but have not gotten all the way to reading the correct data, i.e. I get data from the T/H sensor but it says that it's -5 C inside and I don't believe that since I'm sitting in short-sleeves... Smile

I also found the posts from khgoh (http://forum.pine64.org/showthread.php?tid=231&page=3) and skimmed through the source code for the WifiRemoteI2C server but that is in C (C++) and does not help me at all, or rather, it does not help me solving it in python...

My problem is that the value I get from the T/H sensor does not convert correctly into the ambient temperature and relative humidity.

I would really appreciate if someone told me where I am going wrong and how to correct it.

Many thanks

DS

Source:

Code:
import smbus

import time

bus = smbus.SMBus(1)

address = 0x40

cmd_temp = 0xE3

cmd_humid = 0xE5

temp = 0L

humid = 0L

temp = bus.read_word_data(address, cmd_humid)

print "RH read_word_data returns ", humid

print ""

humid = 125.0 * humid / 65536 - 6

print "RH: ", humid, " %"

print ""

print ""

temp = bus.read_word_data(address, cmd_temp)

print "Temp read_word_data returns ", temp

print ""

temp = 175.72 * temp / 65536 - 46.85

print "Temperature: ", temp, " C"

print ""

print ""

Output:

Code:
debian@pine64:~/i2c$ python getTemp2.py 

RH read_word_data returns  0

RH:  -6.0  %

Temp read_word_data returns  10341

Temperature:  -19.1229412842  C

debian@pine64:~/i2c$

RE: Getting Temperature/Humidity/Ambient Light data with Python - MarkHaysHarris777 - 09-29-2016

The first step is to use the i2c toolset to see if you can see your device address. if your device is on the wrong i2c bus you won't see the address. The (TWI) bus is reserved. Once you know the address of the device , then you can worry about reading it.

Usually, to read an i2c device you first have to write to it; this tells the device which register you want to read-- then you have to know whether the data is coming back to you little-endian or big-endian; and this can make a huge difference in terms of interpretation ( if you have the high and low orders confused the data is not going to make much sense ).

The data-sheet is going to be absolutely necessary.

RE: Getting Temperature/Humidity/Ambient Light data with Python - Yomet - 09-29-2016

Hi MarkHaysHarris777,

Thanks for your reply. I must have been unclear in my first post - I am getting data from the T/H sensor, therefore, I have the correct address and bus. Smile

I was actually thinking about litte-endian vs. big-endian as the cause of my problem since I can see that the T/H sensor sends the result MSB-LSB (can't remember which of the endians that is). So you suggest that I need to switch the order of the returned bytes and the do the conversion again?

When you say that I must first write to the I2C device and then read. Do you mean that the smbus command "read_word_data(addr,cmd)" does not write the code in cmd before reading? The only documentation I found is here. I tried writing the command first (using write_byte(0x40, 0xE5)) and then issuing "read_word_data(0x40, 0xE5)" but get similar results.

I am probably missing some essential part that is right under my nose... Sad

RE: Getting Temperature/Humidity/Ambient Light data with Python - Yomet - 09-29-2016

So I got an answer with code from DonH, thank you very much! :thumbs_up:

In order to share the knowledge I am pasting the code he sent me. Essentially you need to tell the sensor to do a measurement and then read the result - which, ironically, is what I did to start with. Except that I only waited 0.02 seconds whereas this code waits 0.5 seconds...

Here's the code, originally from ControlEverything.com and modified for this purpose by DonH:

# Distributed with a free-will license.
# Use it any way you want, profit or free, provided it fits in the licenses of its associated works.
# STS21
# This code is designed to work with the STS21_I2CS I2C Mini Module available from ControlEverything.com.
# https://www.controleverything.com/conten...t_tabset-2

import smbus
import time

# Get I2C bus
bus = smbus.SMBus(1)

# STS21 address, 0x4A(74)
# Select Command
# 0xF3(243) Temperature measurement in NO HOLD mode
bus.write_byte(0x40, 0xF3)

time.sleep(0.5)

# STS21 address, 0x4A(74)
# Read data back, 2 bytes, MSB first
data0 = bus.read_byte(0x40)
data1 = bus.read_byte(0x40)

# Convert the data
temp = (data0 * 256 + data1) & 0xFFFC
cTemp = -46.85 + (175.72 * temp / 65536.0)
fTemp = cTemp * 1.8 + 32

# Output data to screen
print ("Temperature in Celsius is : %.2f C") %cTemp
print ("Temperature in Fahrenheit is : %.2f F") %fTemp

bus.write_byte(0x40, 0xF5)

time.sleep(0.5)

data2 = bus.read_byte(0x40)
data3 = bus.read_byte(0x40)

humidity = (data2 * 256 + data3) & 0xFFFC

rHumidity = ((125*humidity)/65536)-6

print ("Relative humidity is : %.2f ") %rHumidity

RE: Getting Temperature/Humidity/Ambient Light data with Python - Yomet - 10-01-2016

In order to complete this request I will now post the code I put together for measuring the Lux value from the Ambient Light Sensor.
This code is mostly from the manufacturer of the sensor that is used, or rather the sensor used is based on this one ("Base on TAOS/AMS TSL2561T I2C Light Sensor").

The original code was in C/C++ but I ported it to Python, please tell me if I made mistakes in porting the code, and the reading of the device registers is based on above code.

Have fun Smile

Yomet

Code:
# -*- coding: utf-8 -*-

import smbus

import time

#==================================================================================

#==================================================================================

#==================================================================================

#==================================================================================

# The following code has been adapted from the manufacturers suggested code for converting 

# the Ambient Light measures in Channel 0 and Channel 1 to a Lux value. 

# Ch0 = visible & IR light

# Ch1 = IR light only

# Original code was in C and is available at :

# http://ams.com/eng/content/download/250094/975485/142937

#**************************************************************************** 

# Copyright ams AG, Inc.

#

# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR

# IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A

# PARTICULAR PURPOSE.

#

# Module Name: lux.cpp

#

#****************************************************************************

#unsigned int CalculateLux(unsigned int iGain, unsigned int tInt, unsigned int ch0, unsigned int ch1, int iType)

def CalculateLux(iGain, tInt, ch0, ch1, iType):

    LUX_SCALE = 14 # scale by 2^14

    RATIO_SCALE = 9 # scale ratio by 2^9

    #---------------------------------------------------

    # Integration time scaling factors

    #---------------------------------------------------

    CH_SCALE = 10 # scale channel values by 2^10

    CHSCALE_TINT0 = 0x7517 # 322/11 * 2^CH_SCALE

    CHSCALE_TINT1 = 0x0fe7 # 322/81 * 2^CH_SCALE

    #---------------------------------------------------

    # T, FN, and CL Package coefficients

    #---------------------------------------------------

    # For Ch1/Ch0=0.00 to 0.50

    #    Lux/Ch0=0.0304-0.062*((Ch1/Ch0)^1.4)

    #    piecewise approximation

    #       For Ch1/Ch0=0.00 to 0.125:

    #          Lux/Ch0=0.0304-0.0272*(Ch1/Ch0)

    #       For Ch1/Ch0=0.125 to 0.250:

    #          Lux/Ch0=0.0325-0.0440*(Ch1/Ch0)

    #       For Ch1/Ch0=0.250 to 0.375:

    #          Lux/Ch0=0.0351-0.0544*(Ch1/Ch0)

    #       For Ch1/Ch0=0.375 to 0.50:

    #          Lux/Ch0=0.0381-0.0624*(Ch1/Ch0)

    # For Ch1/Ch0=0.50 to 0.61:

    #    Lux/Ch0=0.0224-0.031*(Ch1/Ch0)

    # For Ch1/Ch0=0.61 to 0.80:

    #    Lux/Ch0=0.0128-0.0153*(Ch1/Ch0)

    # For Ch1/Ch0=0.80 to 1.30:

    #    Lux/Ch0=0.00146-0.00112*(Ch1/Ch0)

    # For Ch1/Ch0>1.3:

    #    Lux/Ch0=0

    #---------------------------------------------------

    K1T = 0x0040 # 0.125 * 2^RATIO_SCALE

    B1T = 0x01f2 # 0.0304 * 2^LUX_SCALE

    M1T = 0x01be # 0.0272 * 2^LUX_SCALE

    K2T = 0x0080 # 0.250 * 2^RATIO_SCALE

    B2T = 0x0214 # 0.0325 * 2^LUX_SCALE

    M2T = 0x02d1 # 0.0440 * 2^LUX_SCALE

    K3T = 0x00c0 # 0.375 * 2^RATIO_SCALE

    B3T = 0x023f # 0.0351 * 2^LUX_SCALE

    M3T = 0x037b # 0.0544 * 2^LUX_SCALE

    K4T = 0x0100 # 0.50 * 2^RATIO_SCALE

    B4T = 0x0270 # 0.0381 * 2^LUX_SCALE

    M4T = 0x03fe # 0.0624 * 2^LUX_SCALE

    K5T = 0x0138 # 0.61 * 2^RATIO_SCALE

    B5T = 0x016f # 0.0224 * 2^LUX_SCALE

    M5T = 0x01fc # 0.0310 * 2^LUX_SCALE

    K6T = 0x019a # 0.80 * 2^RATIO_SCALE

    B6T = 0x00d2 # 0.0128 * 2^LUX_SCALE

    M6T = 0x00fb # 0.0153 * 2^LUX_SCALE

    K7T = 0x029a # 1.3 * 2^RATIO_SCALE

    B7T = 0x0018 # 0.00146 * 2^LUX_SCALE

    M7T = 0x0012 # 0.00112 * 2^LUX_SCALE

    K8T = 0x029a # 1.3 * 2^RATIO_SCALE

    B8T = 0x0000 # 0.000 * 2^LUX_SCALE

    M8T = 0x0000 # 0.000 * 2^LUX_SCALE

    #---------------------------------------------------

    # CS package coefficients

    #---------------------------------------------------

    # For 0 <= Ch1/Ch0 <= 0.52

    #    Lux/Ch0 = 0.0315-0.0593*((Ch1/Ch0)^1.4)

    #    piecewise approximation

    #       For 0 <= Ch1/Ch0 <= 0.13

    #          Lux/Ch0 = 0.0315-0.0262*(Ch1/Ch0)

    #       For 0.13 <= Ch1/Ch0 <= 0.26

    #          Lux/Ch0 = 0.0337-0.0430*(Ch1/Ch0)

    #       For 0.26 <= Ch1/Ch0 <= 0.39

    #          Lux/Ch0 = 0.0363-0.0529*(Ch1/Ch0)

    #       For 0.39 <= Ch1/Ch0 <= 0.52

    #          Lux/Ch0 = 0.0392-0.0605*(Ch1/Ch0)

    # For 0.52 < Ch1/Ch0 <= 0.65

    #    Lux/Ch0 = 0.0229-0.0291*(Ch1/Ch0)

    # For 0.65 < Ch1/Ch0 <= 0.80

    #    Lux/Ch0 = 0.00157-0.00180*(Ch1/Ch0)

    # For 0.80 < Ch1/Ch0 <= 1.30

    #    Lux/Ch0 = 0.00338-0.00260*(Ch1/Ch0)

    # For Ch1/Ch0 > 1.30

    #    Lux = 0

    #---------------------------------------------------

    K1C = 0x0043 # 0.130 * 2^RATIO_SCALE

    B1C = 0x0204 # 0.0315 * 2^LUX_SCALE

    M1C = 0x01ad # 0.0262 * 2^LUX_SCALE

    K2C = 0x0085 # 0.260 * 2^RATIO_SCALE

    B2C = 0x0228 # 0.0337 * 2^LUX_SCALE

    M2C = 0x02c1 # 0.0430 * 2^LUX_SCALE

    K3C = 0x00c8 # 0.390 * 2^RATIO_SCALE

    B3C = 0x0253 # 0.0363 * 2^LUX_SCALE

    M3C = 0x0363 # 0.0529 * 2^LUX_SCALE

    K4C = 0x010a # 0.520 * 2^RATIO_SCALE

    B4C = 0x0282 # 0.0392 * 2^LUX_SCALE

    M4C = 0x03df # 0.0605 * 2^LUX_SCALE

    K5C = 0x014d # 0.65 * 2^RATIO_SCALE

    B5C = 0x0177 # 0.0229 * 2^LUX_SCALE

    M5C = 0x01dd # 0.0291 * 2^LUX_SCALE

    K6C = 0x019a # 0.80 * 2^RATIO_SCALE

    B6C = 0x0101 # 0.0157 * 2^LUX_SCALE

    M6C = 0x0127 # 0.0180 * 2^LUX_SCALE

    K7C = 0x029a # 1.3 * 2^RATIO_SCALE

    B7C = 0x0037 # 0.00338 * 2^LUX_SCALE

    M7C = 0x002b # 0.00260 * 2^LUX_SCALE

    K8C = 0x029a # 1.3 * 2^RATIO_SCALE

    B8C = 0x0000 # 0.000 * 2^LUX_SCALE

    M8C = 0x0000 # 0.000 * 2^LUX_SCALE

    # lux equation approximation without floating point calculations

    #////////////////////////////////////////////////////////////////////////////

    # Routine: unsigned int CalculateLux(unsigned int ch0, unsigned int ch0, int iType)

    #

    # Description: Calculate the approximate illuminance (lux) given the raw

    #              channel values of the TSL2560. The equation if implemented

    #              as a piece-wise linear approximation.

    #

    # Arguments: unsigned int iGain - gain, where 0:1X, 1:16X

    #            unsigned int tInt - integration time, where 0:13.7mS, 1:100mS, 2:402mS, 3:Manual

    #            unsigned int ch0 - raw channel value from channel 0 of TSL2560

    #            unsigned int ch1 - raw channel value from channel 1 of TSL2560

    #            unsigned int iType - package type (T or CS)

    #

    # Return: unsigned int - the approximate illuminance (lux)

    #

    #////////////////////////////////////////////////////////////////////////////

    #------------------------------------------------------------------------

    # first, scale the channel values depending on the gain and integration time

    # 16X, 402mS is nominal.

    # scale if integration time is NOT 402 msec

    chScale = 0L

    channel1 = 0L

    channel0 = 0L

    if tInt == 0: # 13.7 msec

        chScale = CHSCALE_TINT0

    elif tInt == 1: # 101 msec

        chScale = CHSCALE_TINT1

    else: # assume no scaling

        chScale = (1 << CH_SCALE)

    # scale if gain is NOT 16X

    if iGain == 0:

        chScale = chScale << 4 # scale 1X to 16X

    # scale the channel values

    channel0 = (ch0 * chScale) >> CH_SCALE

    channel1 = (ch1 * chScale) >> CH_SCALE

    #------------------------------------------------------------------------

    # find the ratio of the channel values (Channel1/Channel0)

    # protect against divide by zero

    ratio1 = 0L

    if channel0 != 0: 

        ratio1 = (channel1 << (RATIO_SCALE+1)) / channel0

    # round the ratio value

    ratio = (ratio1 + 1) >> 1;

    b = 0

    m = 0

    if iType == 0: # T, FN and CL package

        if ((ratio >= 0) and (ratio <= K1T)):

            b = B1T

            m = M1T

        elif (ratio <= K2T):

            b = B2T

            m = M2T

        elif (ratio <= K3T):

            b = B3T

            m = M3T

        elif (ratio <= K4T):

            b = B4T

            m = M4T

        elif (ratio <= K5T):

            b = B5T

            m = M5T

        elif (ratio <= K6T):

            b = B6T

            m = M6T

        elif (ratio <= K7T):

            b = B7T

            m = M7T

        elif (ratio > K8T):

            b = B8T

            m = M8T

    elif iType == 1:# CS package

        if ((ratio >= 0) and (ratio <= K1C)):

            b = B1C

            m = M1C

        elif (ratio <= K2C):

            b = B2C

            m = M2C

        elif (ratio <= K3C):

            b = B3C

            m = M3C

        elif (ratio <= K4C):

            b = B4C

            m = M4C

        elif (ratio <= K5C):

            b = B5C

            m = M5C

        elif (ratio <= K6C):

            b = B6C

            m = M6C

        elif (ratio <= K7C):

            b = B7C

            m = M7C

        elif (ratio > K8C):

            b = B8C

            m = M8C

    temp = 0L

    temp = ((channel0 * b) - (channel1 * m))

    # do not allow negative lux value

    if temp < 0:

        temp = 0

    temp += (1 << (LUX_SCALE-1))

    # strip off fractional portion

    lux = 0L

    lux = temp >> LUX_SCALE

    return lux

#==================================================================================

#==================================================================================

#==================================================================================

#==================================================================================

bus = smbus.SMBus(1)

address = 0x49

#Start the device, only needs to be done when the device is first booted

bus.write_byte_data(address, 0x80, 0x03)

time.sleep(0.5)

# Specs on the spec sheet page 30 (Basic Operation)

# TSL2560-61_DS000110_2-00.pdf

Ch0L = bus.read_byte_data(address, 0x8C)

Ch0H = bus.read_byte_data(address, 0x8D)

Ch0 = Ch0H * 256 + Ch0L

Ch1L = bus.read_byte_data(address, 0x8E)

Ch1H = bus.read_byte_data(address, 0x8F)

Ch1 = Ch1H * 256 + Ch1L

# If I understood the technical documents correctly, the Ambient Light Sensor that

# Pine64 uses should use the FN package calculations.

# http://ams.com/eng/Products/Light-Sensors/Ambient-Light-Sensors/TSL2561

# under Technical Documents / Using the Lux Equation

# http://ams.com/eng/content/view/download/145438

print "Calculation of Lux according to the T, FN and CL packages"

light = CalculateLux(0, 2, Ch0, Ch1, 0) # T, FN and CL package

print "Lux = ", light

#print "Calculation of Lux according to the CS package"

#light = CalculateLux(0, 2, Ch0, Ch1, 1) # CS package

#print "Lux = ", light

RE: Getting Temperature/Humidity/Ambient Light data with Python - MarkHaysHarris777 - 10-01-2016

Congratulations !

RE: Getting Temperature/Humidity/Ambient Light data with Python - Artyom - 10-01-2016

Hi again.
I add new sensors test here: http://forum.pine64.org/showthread.php?tid=2274&pid=20736#pid20736
Now you can test library. Download from here: https://github.com/blademoon/Sensus
If you have comments or suggestions, please contact me.

RE: Getting Temperature/Humidity/Ambient Light data with Python - Yomet - 10-01-2016

(10-01-2016, 02:51 AM)MarkHaysHarris777 Wrote: Congratulations !

Thanks!

RE: Getting Temperature/Humidity/Ambient Light data with Python - tllim - 10-02-2016

(10-01-2016, 02:40 AM)Yomet Wrote: In order to complete this request I will now post the code I put together for measuring the Lux value from the Ambient Light Sensor.
This code is mostly from the manufacturer of the sensor that is used, or rather the sensor used is based on this one ("Base on TAOS/AMS TSL2561T I2C Light Sensor").

The original code was in C/C++ but I ported it to Python, please tell me if I made mistakes in porting the code, and the reading of the device registers is based on above code.

Have fun

Yomet

Code:
# -*- coding: utf-8 -*- import smbus import time #================================================================================== #================================================================================== #================================================================================== #================================================================================== # The following code has been adapted from the manufacturers suggested code for converting # the Ambient Light measures in Channel 0 and Channel 1 to a Lux value. # Ch0 = visible & IR light # Ch1 = IR light only # Original code was in C and is available at : # http://ams.com/eng/content/download/250094/975485/142937 #**************************************************************************** # Copyright ams AG, Inc. # # THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A # PARTICULAR PURPOSE. # # Module Name: lux.cpp # #**************************************************************************** #unsigned int CalculateLux(unsigned int iGain, unsigned int tInt, unsigned int ch0, unsigned int ch1, int iType) def CalculateLux(iGain, tInt, ch0, ch1, iType): LUX_SCALE = 14 # scale by 2^14 RATIO_SCALE = 9 # scale ratio by 2^9 #--------------------------------------------------- # Integration time scaling factors #--------------------------------------------------- CH_SCALE = 10 # scale channel values by 2^10 CHSCALE_TINT0 = 0x7517 # 322/11 * 2^CH_SCALE CHSCALE_TINT1 = 0x0fe7 # 322/81 * 2^CH_SCALE #--------------------------------------------------- # T, FN, and CL Package coefficients #--------------------------------------------------- # For Ch1/Ch0=0.00 to 0.50 # Lux/Ch0=0.0304-0.062*((Ch1/Ch0)^1.4) # piecewise approximation # For Ch1/Ch0=0.00 to 0.125: # Lux/Ch0=0.0304-0.0272*(Ch1/Ch0) # For Ch1/Ch0=0.125 to 0.250: # Lux/Ch0=0.0325-0.0440*(Ch1/Ch0) # For Ch1/Ch0=0.250 to 0.375: # Lux/Ch0=0.0351-0.0544*(Ch1/Ch0) # For Ch1/Ch0=0.375 to 0.50: # Lux/Ch0=0.0381-0.0624*(Ch1/Ch0) # For Ch1/Ch0=0.50 to 0.61: # Lux/Ch0=0.0224-0.031*(Ch1/Ch0) # For Ch1/Ch0=0.61 to 0.80: # Lux/Ch0=0.0128-0.0153*(Ch1/Ch0) # For Ch1/Ch0=0.80 to 1.30: # Lux/Ch0=0.00146-0.00112*(Ch1/Ch0) # For Ch1/Ch0>1.3: # Lux/Ch0=0 #--------------------------------------------------- K1T = 0x0040 # 0.125 * 2^RATIO_SCALE B1T = 0x01f2 # 0.0304 * 2^LUX_SCALE M1T = 0x01be # 0.0272 * 2^LUX_SCALE K2T = 0x0080 # 0.250 * 2^RATIO_SCALE B2T = 0x0214 # 0.0325 * 2^LUX_SCALE M2T = 0x02d1 # 0.0440 * 2^LUX_SCALE K3T = 0x00c0 # 0.375 * 2^RATIO_SCALE B3T = 0x023f # 0.0351 * 2^LUX_SCALE M3T = 0x037b # 0.0544 * 2^LUX_SCALE K4T = 0x0100 # 0.50 * 2^RATIO_SCALE B4T = 0x0270 # 0.0381 * 2^LUX_SCALE M4T = 0x03fe # 0.0624 * 2^LUX_SCALE K5T = 0x0138 # 0.61 * 2^RATIO_SCALE B5T = 0x016f # 0.0224 * 2^LUX_SCALE M5T = 0x01fc # 0.0310 * 2^LUX_SCALE K6T = 0x019a # 0.80 * 2^RATIO_SCALE B6T = 0x00d2 # 0.0128 * 2^LUX_SCALE M6T = 0x00fb # 0.0153 * 2^LUX_SCALE K7T = 0x029a # 1.3 * 2^RATIO_SCALE B7T = 0x0018 # 0.00146 * 2^LUX_SCALE M7T = 0x0012 # 0.00112 * 2^LUX_SCALE K8T = 0x029a # 1.3 * 2^RATIO_SCALE B8T = 0x0000 # 0.000 * 2^LUX_SCALE M8T = 0x0000 # 0.000 * 2^LUX_SCALE #--------------------------------------------------- # CS package coefficients #--------------------------------------------------- # For 0 <= Ch1/Ch0 <= 0.52 # Lux/Ch0 = 0.0315-0.0593*((Ch1/Ch0)^1.4) # piecewise approximation # For 0 <= Ch1/Ch0 <= 0.13 # Lux/Ch0 = 0.0315-0.0262*(Ch1/Ch0) # For 0.13 <= Ch1/Ch0 <= 0.26 # Lux/Ch0 = 0.0337-0.0430*(Ch1/Ch0) # For 0.26 <= Ch1/Ch0 <= 0.39 # Lux/Ch0 = 0.0363-0.0529*(Ch1/Ch0) # For 0.39 <= Ch1/Ch0 <= 0.52 # Lux/Ch0 = 0.0392-0.0605*(Ch1/Ch0) # For 0.52 < Ch1/Ch0 <= 0.65 # Lux/Ch0 = 0.0229-0.0291*(Ch1/Ch0) # For 0.65 < Ch1/Ch0 <= 0.80 # Lux/Ch0 = 0.00157-0.00180*(Ch1/Ch0) # For 0.80 < Ch1/Ch0 <= 1.30 # Lux/Ch0 = 0.00338-0.00260*(Ch1/Ch0) # For Ch1/Ch0 > 1.30 # Lux = 0 #--------------------------------------------------- K1C = 0x0043 # 0.130 * 2^RATIO_SCALE B1C = 0x0204 # 0.0315 * 2^LUX_SCALE M1C = 0x01ad # 0.0262 * 2^LUX_SCALE K2C = 0x0085 # 0.260 * 2^RATIO_SCALE B2C = 0x0228 # 0.0337 * 2^LUX_SCALE M2C = 0x02c1 # 0.0430 * 2^LUX_SCALE K3C = 0x00c8 # 0.390 * 2^RATIO_SCALE B3C = 0x0253 # 0.0363 * 2^LUX_SCALE M3C = 0x0363 # 0.0529 * 2^LUX_SCALE K4C = 0x010a # 0.520 * 2^RATIO_SCALE B4C = 0x0282 # 0.0392 * 2^LUX_SCALE M4C = 0x03df # 0.0605 * 2^LUX_SCALE K5C = 0x014d # 0.65 * 2^RATIO_SCALE B5C = 0x0177 # 0.0229 * 2^LUX_SCALE M5C = 0x01dd # 0.0291 * 2^LUX_SCALE K6C = 0x019a # 0.80 * 2^RATIO_SCALE B6C = 0x0101 # 0.0157 * 2^LUX_SCALE M6C = 0x0127 # 0.0180 * 2^LUX_SCALE K7C = 0x029a # 1.3 * 2^RATIO_SCALE B7C = 0x0037 # 0.00338 * 2^LUX_SCALE M7C = 0x002b # 0.00260 * 2^LUX_SCALE K8C = 0x029a # 1.3 * 2^RATIO_SCALE B8C = 0x0000 # 0.000 * 2^LUX_SCALE M8C = 0x0000 # 0.000 * 2^LUX_SCALE # lux equation approximation without floating point calculations #//////////////////////////////////////////////////////////////////////////// # Routine: unsigned int CalculateLux(unsigned int ch0, unsigned int ch0, int iType) # # Description: Calculate the approximate illuminance (lux) given the raw # channel values of the TSL2560. The equation if implemented # as a piece-wise linear approximation. # # Arguments: unsigned int iGain - gain, where 0:1X, 1:16X # unsigned int tInt - integration time, where 0:13.7mS, 1:100mS, 2:402mS, 3:Manual # unsigned int ch0 - raw channel value from channel 0 of TSL2560 # unsigned int ch1 - raw channel value from channel 1 of TSL2560 # unsigned int iType - package type (T or CS) # # Return: unsigned int - the approximate illuminance (lux) # #//////////////////////////////////////////////////////////////////////////// #------------------------------------------------------------------------ # first, scale the channel values depending on the gain and integration time # 16X, 402mS is nominal. # scale if integration time is NOT 402 msec chScale = 0L channel1 = 0L channel0 = 0L if tInt == 0: # 13.7 msec chScale = CHSCALE_TINT0 elif tInt == 1: # 101 msec chScale = CHSCALE_TINT1 else: # assume no scaling chScale = (1 << CH_SCALE) # scale if gain is NOT 16X if iGain == 0: chScale = chScale << 4 # scale 1X to 16X # scale the channel values channel0 = (ch0 * chScale) >> CH_SCALE channel1 = (ch1 * chScale) >> CH_SCALE #------------------------------------------------------------------------ # find the ratio of the channel values (Channel1/Channel0) # protect against divide by zero ratio1 = 0L if channel0 != 0: ratio1 = (channel1 << (RATIO_SCALE+1)) / channel0 # round the ratio value ratio = (ratio1 + 1) >> 1; b = 0 m = 0 if iType == 0: # T, FN and CL package if ((ratio >= 0) and (ratio <= K1T)): b = B1T m = M1T elif (ratio <= K2T): b = B2T m = M2T elif (ratio <= K3T): b = B3T m = M3T elif (ratio <= K4T): b = B4T m = M4T elif (ratio <= K5T): b = B5T m = M5T elif (ratio <= K6T): b = B6T m = M6T elif (ratio <= K7T): b = B7T m = M7T elif (ratio > K8T): b = B8T m = M8T elif iType == 1:# CS package if ((ratio >= 0) and (ratio <= K1C)): b = B1C m = M1C elif (ratio <= K2C): b = B2C m = M2C elif (ratio <= K3C): b = B3C m = M3C elif (ratio <= K4C): b = B4C m = M4C elif (ratio <= K5C): b = B5C m = M5C elif (ratio <= K6C): b = B6C m = M6C elif (ratio <= K7C): b = B7C m = M7C elif (ratio > K8C): b = B8C m = M8C temp = 0L temp = ((channel0 * b) - (channel1 * m)) # do not allow negative lux value if temp < 0: temp = 0 temp += (1 << (LUX_SCALE-1)) # strip off fractional portion lux = 0L lux = temp >> LUX_SCALE return lux #================================================================================== #================================================================================== #================================================================================== #================================================================================== bus = smbus.SMBus(1) address = 0x49 #Start the device, only needs to be done when the device is first booted bus.write_byte_data(address, 0x80, 0x03) time.sleep(0.5) # Specs on the spec sheet page 30 (Basic Operation) # TSL2560-61_DS000110_2-00.pdf Ch0L = bus.read_byte_data(address, 0x8C) Ch0H = bus.read_byte_data(address, 0x8D) Ch0 = Ch0H * 256 + Ch0L Ch1L = bus.read_byte_data(address, 0x8E) Ch1H = bus.read_byte_data(address, 0x8F) Ch1 = Ch1H * 256 + Ch1L # If I understood the technical documents correctly, the Ambient Light Sensor that # Pine64 uses should use the FN package calculations. # http://ams.com/eng/Products/Light-Sensors/Ambient-Light-Sensors/TSL2561 # under Technical Documents / Using the Lux Equation # http://ams.com/eng/content/view/download/145438 print "Calculation of Lux according to the T, FN and CL packages" light = CalculateLux(0, 2, Ch0, Ch1, 0) # T, FN and CL package print "Lux = ", light #print "Calculation of Lux according to the CS package" #light = CalculateLux(0, 2, Ch0, Ch1, 1) # CS package #print "Lux = ", light

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