10-02-2016, 02:36 PM
(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
Bravo !!!