how to test LED driver LP5523 in order to integrate blinking patterns

Hi,

Can you give more details about your testing requirement? Do you want to measure the LED pattern (generated by the LP5523 software) from the LED pins with oscilloscope? If this is the case, LED voltage could be fed to a low-pass RC filter and measure the filter output voltage with an oscilloscope.

Or you can use a logic analyzer to measure the PWM signal and generate test data from that set of PWM values. I have no experience on Beagle Bone, but I would think that it's possible to use it's input capture counters/timers to measure PWM and generate test data.

BR,
Jussi

hello br,

thanks  for your info.basically.we r generating  different blinking patterns on the LP5523 Evaluation Kit using an application running on the cc2650 dev kit.so i am using LP5523evalution kit (msp430 bases) .so after generating  different (tingle,sinusoidal ) led blink pattern.how i am going to test  that pattern is correct or not with respect to pwm or  what ?i am in confusion how can i simulate or test correct way where i can conform yes respective led pattern is correct as per input  with help of oscilloscope .

Thanks

tapas

Hi,

There is no simple way to do that, usually customers just look on the LED output(s). I've done similar PWM measurements earlier (not for LP5523) by using an USB logic analyzer (USBee) to save the PWM data as logic 0/1, then parsing that data with a Python-script to calculate PWM values and write PWM data to CSV-file. Benefit of this method is that you can measure many digital channels simultaneously and generate test data for all channels. Drawback is that the data needs to be parsed to PWM value before plotting it so it's not live measurement.

Analog testing directly with an oscilloscope is tricky as you can see only the PWM changing but not actual ramps live. So for that you'll need to filter the PWM to analog signal. Here's a TI Designs TIPD127 "PWM to 12-bit Analog Signal Conversion Circuit" http://www.ti.com/tool/tipd127 which describes LPF design for PWM to analog conversion.

-Jussi

Hello Jussi,

really nice reply. basically we r  setting the pwm value to particular register to see the output  of different pattern .so manually we can see that pattern in oscilloscope but  as a tester how he can test  automatically using  script or any method .by the way u already describe some solution .we r not using any gpio pin .we r using 13 led  to visualise the led pattern.

many thanks

Hi,

For mass testing would it be enough if you read back the SRAM of the LP5523 and verify that it was programmed correctly? As it is tricky to test the LED patterns directly from LED pins.

BR,

Jussi