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Document Feedback 

TSL2521 ALS/Flicker 

 

 

TSL2521 ALS and Flicker Settings 

 

 

Application Note 

• PUBLIC 

 

AN001042 

• v1-01 • 2022-Jan-27 

23

 

│ 12 

 

mod_calib_nth_iteration_agc_enable in register 

MOD_CALIB_CFG2

. Please note that this bit is not 

enabled by default but has to be enabled to use one or both of the AGC methods. 

 

 

Information 

 

The same mode_calib_nth_iteration setting is used for the Autozero as well. Since the ALS 
Autozero procedure can take a longer time it might be necessary to disable the bit 
mod_calib_nth_iteration_az_enable in register 

MOD_CALIB_CFG2

 after the first measurement. For 

this purpose a single measurement can be done after startup either by setting 
mode_calib_nth_iteration to 1 and setting the bit stop_after_nth_iteration in register 

MEAS_MODE0

 

or just by stopping the measurement after getting the first result. After that Autozero can be disabled 
by clearing bit mod_calib_nth_iteration_az_enable. 

 

2.6 

Wait Time 

Related to ALS measurement on legacy ALS devices like TCS3707 was the Wait time that defined the 
sample rate of the ALS measurement 

– and therefore had to be higher than the set ALS integration 

time. The way to activate this WTIME was to set the enable Bit WEN in the ENABLE register. 

WTIME

 is present on TSL2521 as well, but there is no WEN necessary anymore. Instead, there is the 

additional bit field mod_trigger_timing in register 

TRIGGER_MODE

 that either switches off the Wait 

time or defines the time base multiplicator for 

WTIME

. 

Additionally, the Wait time needs to be activated for each sequencer step individually in bit field 
measurement_sequencer_wait_pattern in register 

MEAS_SEQR_RESIDUAL_1_AND_WAIT

.  

As for all sequencer pattern registers on TSL2521 the default value is the right one if only sequence 
step 0 is used. 

 

 

Information 

 

Please note that on TSL2521 the Wait time needs to be higher than both the ALS integration time 
and the Flicker measurement time to have an effect.  

 

Содержание ams TSL2521

Страница 1: ...Product Document Published by ams OSRAM Group...

Страница 2: ...Application Note AN001042 TSL2521 ALS Flicker Settings and Comparison to Legacy ALS Devices v1 01 2022 Jan 27...

Страница 3: ...C 11 2 6 Wait Time 12 3 ALS Result Data Format 13 3 1 Internal Data Format 13 3 2 16 Bit Data Full Count Results in ALS_DATA Registers 14 3 3 20 Bit Data Result in ALS_DATA Registers Including 4 Bit R...

Страница 4: ...e data compression features and measurements can be planned in sequences with individual settings Additionally a new residual measurement feature offers higher resolution at lower gain These new featu...

Страница 5: ...odes like Clear C and Infrared IR but after the two available ALS modulators modulator 0 and modulator 1 Figure 1 shows the number and filter type of the six available photodiodes on TSL2521 The photo...

Страница 6: ...ement_sequencer_als_pattern in register MEAS_SEQR_ALS_FD_1 for both modulators by default ALS with both modulators is enabled for step 0 only Flicker measurement can be enabled for each modulator indi...

Страница 7: ...ution results in an effective gain of 4096x in this case but at the gain non linearity of 256x which is rather low In order to use the second gain table mod_gain_select has to be set to 3 before start...

Страница 8: ...red or not the way to get back to the same number space comparable to legacy devices is to divide the results by 16 in this case the decimal places show the residual amount The GUI provided by ams OSR...

Страница 9: ...al measurement time This reduces the ALS integration time accordingly but only by a very small amount and in case of no flicker measurement during the same step most times it can be neglected as shown...

Страница 10: ...n as set in fd_nr_samples in registers FD_NR_SAMPLES0 and FD_NR_SAMPLES1 and increases at the same time the ALS result as often as set in als_nr_samples in registers ALS_NR_SAMPLES0 and ALS_NR_SAMPLES...

Страница 11: ...ation and Proposed Settings Item Value dec Customer Example Specification Update interval 0 5 s ALS integraton time 50 ms Max flicker frequency 2 kHz FFT bin size 10 Hz Proposal Sample time 125 s Samp...

Страница 12: ...nt_sequencer_agc_asat_pattern in register MEAS_SEQR_STEP1_MOD_PHDX_SMUX_H individually for each sequencer step This setting is valid for both modulators The second one is the predict AGC that defines...

Страница 13: ...sabled by clearing bit mod_calib_nth_iteration_az_enable 2 6 Wait Time Related to ALS measurement on legacy ALS devices like TCS3707 was the Wait time that defined the sample rate of the ALS measureme...

Страница 14: ...As shown in Figure 10 the maximum result width of 26 bit including 4 bit Residual counts requires als_msb_position to be set to 6 In most applications the second shown format of 24 bit is a good setti...

Страница 15: ...taining Residuals later since the number space is a different one without the 4 bits on LSB side 3 3 20 Bit Data Result in ALS_DATA Registers Including 4 Bit Residuals It is possible to transfer the 1...

Страница 16: ...full counts result in the ALS_DATAx is shifted by 4 bits to the left or simply multiplied by 16 on host side to keep the data consistent over the whole range and to stay in the same 20 bit number spa...

Страница 17: ...urement in different steps of the sequencer If this is not possible the bit do_als_final_processing in register CFG1 has to be set This delays the writing of ALS data until all flicker data is written...

Страница 18: ...0xFFFE in case of 24 bit FIFO format to 0xFFFFFE Digital saturation sets the modulator interrupt flag mint in register STATUS as well Like for analog saturation this can be solved by reducing the gain...

Страница 19: ...Document Feedback TSL2521 ALS Flicker ALS Result Data Format Application Note PUBLIC AN001042 v1 01 2022 Jan 27 23 18 Equation 8 _ _ _ _ _ _ 1 _ 1 22 16...

Страница 20: ...to reduce the number of transferred flicker data bits in order to reduce I2 C traffic For high flicker samples rates the dynamic range is lower so the absolute number of bits of a transferred sample...

Страница 21: ...t reduces the I2 C traffic significantly the drivers provided by ams OSRAM show and document the use of these features 4 3 Flicker Data Transfer Via FIFO Flicker data is always written to the FIFO if...

Страница 22: ...1 Bit and Filled Up FIFO Byte The flicker data can be read out from register FIFO_DATA at any time The right procedure is to get firstly fifo_lvl by reading FIFO_LEVEL 0xFD and FIFO_STATUS0 0xFE as bl...

Страница 23: ...formation Changes from previous version to current revision v1 01 Page Initial version Corrected number of preferred modulator for flicker measurements 4 Page and figure numbers for the previous versi...

Страница 24: ...otice RoHS Compliant ams Green Statement RoHS Compliant The term RoHS compliant means that ams OSRAM AG products fully comply with current RoHS directives Our semiconductor products do not contain any...

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