nRF5 SDK - Tutorial for Beginners Pt 19 - SAADC an Introduction - (Single Ended & Differential) скачать в хорошем качестве

nRF5 SDK - Tutorial for Beginners Pt 19 - SAADC an Introduction - (Single Ended & Differential)

This video is also a part of my on going tutorial series for beginners and in this tutorial we will take a look at how to program ADC for nrf52832 and nrf52840 devices. These devices are equipped with SAADC which is successive approximation analog to digital converter. The SAADC has two methods of reading inputs. One is Single Ended. In this setting we connect a single analog input pin. 2nd is Differential Input. It uses two input pins and we read the input from these two pins. Saadc works in different modes. we can use the blocking mode and non blocking modes for reading input values. we can read adc in single shot mode as well as in continuous mode. Today we will take a look at how to use adc in single shot mode using blocking function, a blocking function blocks the processor until the samples are read from the input pins. Single Ended: A single ended configuration uses 1 pin for reading analogue voltages. A simple formula to calculate the input voltage is given: Vb = [v(p) - v(n)] * Gain / Reference * 2^(n-m) for single ended m =0 Vb = is voltage representation in binary v(p) = voltage read on positive pin of the adc channel v(n) = voltage on negative pin (In single ended mode this is connected with internal ground automatically). so its value is 0. Gain = 1/6 which is selected by default as GAIN_1_6 in config default Reference = connected with internal 0.6V n = is the resolution of ADC for e.g: we read 1.1 volts, and n = 12 and single ended mode is selected then: Vb = [1.1 - 0] * [ (1/6) / (0.6) ] * 2^(12-0) Vb = (1.1) * (0.2778) * 4096 Vb = 1251 for the sake of simplicity we know that due to gain and reference the Input range can be calculated as: Input Range = (Reference) / (Gain) = (0.6) / (1/6) = 3.6V So we can also use this formula to calculate the value: Vb = (Vin / Input Range) * 2^n for above e.g values 1.1 volts, n = 12 Vb = (1.1/3.6) * 4096 Vb = 1251 So the answer is same so we use this simple calculation for default values. So it will store this value in memory 1251 which can be converted back to original voltages Differential : In Differential mode we use two input channels, so we measure the voltage difference between these two channels. Differential mode is good in terms of noise immunity and it is also good for measuring small differential changes for e.g a coin cell battery voltage drop is approx 0.6 volts from 100 percent to 0 percent so differential mode would be a good match for measuring this range. Same formula can be used to calculate the input voltage for differential is: for calculating the signed values: Vb = (V(p) / Input Range) * 2^(n -m) here for differential mode m = 1 Vb : is voltage representation in binary V(p): is the input voltage read on positive pin V(n): in this case we have connected it with internal reference Input Range : 3.6V n : is the resolution of ADC m = 1 for differential mode for e.g: we read 1.1 volts, and n = 10 Vb = (1.1 / 3 .6) * 2^(10-1) Vb = (0.305) * (2^9) = 0.305 * 512 Vb = 156 Hope so this will help in understanding the basics of SAADC for nrf52832 and nrf52840. The codes with brief details are available for download from here: https://drive.google.com/file/d/1bPJl... be sure to download and see the details and play around with it. ;p If you like my work & want me to keep on making more tutorials on these devices, please do support me. You can make a one time donation or buy me a coffee :p on my PayPal Account: PAYPAL: https://www.paypal.com/paypalme/Sembe... just click on this link to proceed, thanks :) You can also support me through my Patron: PATRON:   / sumairsembeddedengineering   just click this link to proceed. Your donations will keep me motivated, as I spend hours & hours to make a good quality content free of cost for everybody. Thanks in Advance... ;p If you want to support me and want to learn the full course including all the code and tutorials then you can buy the full course on my official website, after this course you will be able to transfer data between BLE devices as well as create your own custom services and send custom types of data, so what are you waiting for, hurry up and buy our course, first 50 customers will get it at a discounted price: 👉🏼 https://courses.sumairsembedded.com/c...