PWM FLICKER TEST GENERATOR

The OLED is an absolutely beautiful display - no doubts about it - but there are positives and negatives to it (like most advancements in technology). The videos I took show a clear cut difference between the two displays. I have no idea why that is happening - does anyone with expertise in OLED tech know the answer to that? What caught me even more off guard was finding out that there is PWM flicker on the OLED display even at 100% max brightness. What surprised me was that there was no PWM at all on the IPS panel. I wasn't surprised to see PWM flicker on the OLED display. The results show that there is no PWM flicker on the IPS panel while there is significant PWM flicker on all brightness' on the OLED display. I recorded the videos of both displays at the corresponding brightness' - 0%, 25%, 50%, 75%, & 100%. I tested for PWM flicker by recording videos of static images on both displays side by side in slow-mo at 240 FPS on my iPhone X. Once I had both IPS and OLED versions I decided to test it out myself. I was hearing a lot of rumors about particularly atrocious PWM flicker on the on the 2020 Spectre 15.6 OLED display (HP uses the Samsung SDCA029 panel). Here we use 15-bits, so the range is from 0 to not quite 33,000.Update to my last post. We use more resolution for PWM than is available on the Arduino UNO which defaults to 8-bits, i.e., 0-255. In the example that follows, we will use PWM in conjunction with an ESP32 development board to fade an LED up and down. It is often used to fade an LED up and down, or control a motor. PWM allows us to simulate analog voltages using digital means. This is with the development board face up, and the USB connector oriented down. I repeat this example here to eliminate the need to change to an earlier Instructable, and to provide us with a working example of PWM in action.Р”Р„lmost every pin on the ESP32 development board, used here, accommodates PWM, except for the bottom two pins on both the left and right-side, and the top pin on the left side. It will be the configuration we use with our oscilloscope in the next Step to see a PWM signal. This is the example of PWM from my previous Instructable 'ESP32 Tutorial:Touch, Hall, I2C, PWM, ADC, & DAC'. Sadly, this process cannot be rushed.Р”Р„fter the self-calibration process for the oscilloscope is completed, and assuming we have calibrated a probe(s) as well, we are ready to start using the oscilloscope and probe. This process is quite long and can take several minutes. When the self-calibration is completed we select 'Exit' to end the process (see attached video). We choice 'Start' to begin the self-calibration process (see attached video). We then select 'Self-Cal', or its equivalent, and after selecting it, we are presented with some options, on the Rigol and similar oscilloscopes, these are 'Start' and 'Exit'. The menu to do this is often found through a button such as 'Utility', on the Rigol, or on some other oscilloscopes something similar. We should also disconnect all inputs to the oscilloscope. However, we should calibrate the oscilloscope itself, before it is used (see next step).Р”В«efore we use the oscilloscope it it an excellent idea to calibrate it, with its own internal calibrator.Р”В«efore we use the calibrator we should leave the oscilloscope on for 30 minutes or so to insure that all components are adequately 'warmed' up. When this is completed, the adjusted/calibrated probe is ready to use.

PWM FLICKER TEST GENERATOR

The goal is to use the built in square wave generator to get the sawtooth wave shown as 'flat' as possible without any curves up or down (see attached video). One may want to press 'Auto' on your oscilloscope if the square wave does not show, or is shown only partially. However, there is almost always a sawtooth reference signal generator on benchtop oscilloscopes. This screw is usually located either on the distal end of the probe itself or at the proximal end, near it's BNC connector, i.e., the attachment to the oscilloscope (see attached photographs).Р”Р„ sawtooth reference generator can be found at the bottom right (two flat metal connectors with central square holes) on the Rigol oscilloscope used in this Instructable.Р”Р„ test calibration generator is usually included with all benchtop oscilloscopes, and may appear in a slightly different form, i.e., not as metal plates, than the one used in this Instructable. This is done using the calibration screw on the probe. Before we start we need to calibrate our oscilloscope probe(s).

Pwm flicker test