Diskussion:Ambient Light Lux Sensor VEML7700

#	date	plan for this week	Priority	progress	Comment
1	28.04.26	Ask Mr. Ebmeyer to borrow a luxmeter as a reference (e.g. from Prof. Meyer) Measure the values and the reference to calibrate the characteristic curve use MATLAB regression app compare the characteristic curve in the datasheet to the selfmade Write your new article.	A	In Progress	I have received the Luxmeter from Mr Ebmeyer Started writing the wiki article Data have been taken fo a fixed (Gain 1/8,Integration Time = 100ms) and graph compared to the data sheet which showed similarity but although the datasheet graph used Log-log graph but we can see similar pattern.
2	30.04.26	Make a table for every combination of Gain an Integration Time. Measure the ALS raw for every kombination. Save the Table in your article. What Lux Value should be measured in which combination (Gain/IT)? Measure the values and the reference to calibrate the characteristic curve for every combination (Gain/IT). use MATLAB regression app to fit the curves. compare the characteristic curve in the datasheet to the selfmade Write your new article. Range: [0..140000] Lux	A	In Progress	A table for every combination of Integration Time and Gain has been created and save on matlab for further analysis The table has been created and all the raw ALS values are entered based on every combination of the Gain and Integration Time. Data have been taken fo a fixed (Gain 1/8,Integration Time = 100ms) and graph compared to the data sheet which showed similarity but although the datasheet graph used Log-log graph but we can see similar pattern. Wiki article is updated with the data collected and the graph plotted to show their relationship
3	06.05.26	Range: [0..140000] Lux Make a table for every combination of Gain an Integration Time. Measure the ALS raw for every combination. Save the Table in MATLAB. What Lux Value should be measured in which combination (Gain/IT)? Measure the values and the reference to calibrate the characteristic curve for every combination (Gain/IT). use MATLAB Curve Fitter app to fit the curves. compare the characteristic curve in the datasheet to the selfmade Write your new article. Reference the Luxmeter LX-1108 in the Lab L3.1-E01-130. Measure the raw sensor values without any calculation.	A	In Progress	Table or every combination has been created Raw ALS for every combinations already done The table saved in MATLAB LX-1108 is already referenced with the lab Luxmeter Raw sensor values are measured without any calculation
4	12.05.26	Student was confuse by the tasks. Tasks were discussed and minimized. Please work on the tasks step by step. Start with 1. Reference the Luxmeter LX-1108 in the Lab L3.1-E01-130. Devide the measurement range into 23 measurements e.g. Ref = [0 300 600 900 1000 2000 3000 4000 5000 6000 7000 9000 10000 11000 12000 13000 14000 15000 16000 16000 18000 19000 20000] Lux. Tune the Lamp so the reference Sensor measures them. Measure with the Luxmeter LX-1108 an write the results to a MATLAB array LX = [0 .. 20k] Lux Save the arrays in reference.mat. Plot the reference on x-axis and LX on y-Axis. Discuss the results with Prof. Schneider. Fit the data with a curve/regression (Curve Fitter).	A	Done	The Luxmeter has been referenced in the lab The Measurement range divided into 21 measurements Measured readings written to a MATLAB array Arrays saved to reference.mat file Plot already done Regression used for the data
5	13.05.26	Please work on the tasks step by step. Start with 1, 2, 3,... Learn how to use MATLAB (MATLAB Onramp, Core MATLAB Skills) Learn what a regression analysis is (URL). Learn how to calculate a regression with MATLAB (URL). Use a textbook: e.g. Linear and Nonlinear Regression with MATLAB Learn how to calculate a relative error (URL). The relationship between the reference and the luxmeter appears to be a constant. This constant changes across the value range. Calculate this constant across the value range using nonlinear regression. Implement a function that calculates the real value from the Luxmeter measurement trueLux = Lux2Ref(Lux). Bring your measurement data into Matlab. Correct the LX measurements with the function Lux2Ref(Lux). Save the arrays in a .mat file. Write a MATLAB-funktion ALS2Lux that calculates the real lux value from the Sensor measurement. Automatically choose the optimal gain/IT for the measurement. Take the measurement with the optimal gain/IT. Calculate the Lux value from the ALS value. Go to the light-lab and validate the measurement over the range. Calculate the remaining relative error and display it over the range with MATLAB.	A	Done	Done MATLAB Onramp course learnt Regression Analysis Learnt how to calculate a relative error The Constant across the value range is calculated using nonlinear regression A function is implemented to calculate real value from luxmeter measurement The LX measurement is corrected The Corrected array values is saved in a .mat file Discussion on Sensor-Specific Calibration For task 11, I would like to seek clarity from my supervisor concerning which sensor he was refering to because the subsequent tasks are only specific to VEML7700 sensor The calibration procedure developed in the previous tasks is specific to the LX-1108 lux meter and Lab reference,It cannot be directly applied to the VEML7700 sensor. Unlike the LX-1108 or the lab reference luxmeter, the VEML7700 sensor measurement output depends on both the selected gain and integration time (IT) and this must be fixed before taking the measurement. Consequently, a unique relationship between the laboratory reference lux meter or even LX-1108 and the VEML7700 sensor cannot be established without first specifying the gain and integration-time configuration. The same reference lux value either from the Lab reference or the LX-1108 may produce different ALS readings under different gain and integration-time settings and finally the lux value calculated from it. Therefore, any reference-to-ALS-to-lux relationship derived for the VEML7700 is valid only for the specific gain and integration-time configuration used during calibration, it can not be a general function for correcting ALS.The AlS value is completely dependent on the Gain and Integration Time. The VEML7700 implementation codes in arduino already includes a function that automatically selects the optimal gain and integration-time combination for any current light level according VISHAY documentation. Therefore, the gain and integration-time optimization requested in the subsequent tasks is handled dynamically within the Arduino implementation code before the lux calculation and validation.