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| # | Post Title | Result Info | Date | User | Forum |
| Answer to: What exactly is PWM resolution ? | 16 Relevance | 2 years ago | Admin | Hardware/Schematic | |
| Hey, Note: UNO R3 supports 8-bit PWM resolution, not 10. Higher resolution means the PWM output can be more finely tuned, resulting in a smoother signal. This is particularly important in applications like motor control, LED dimming, and audio signal generation. 8-bit resolution means there are 256 possible duty cycle values (from 0 to 255). That's why the analogWrite(PWM pin, PWM value) takes values bw 0 and 255. In this case, increasing the duty cycle step by step corresponds to a change of approximately 0.4% (1/256) of the full-scale value. Whereas the 16-bit resolution means there are 65,536 possible duty cycle values (from 0 to 65,535).Each step in the duty cycle corresponds to a change of approximately 0.0015% (1/65,536) of the full-scale value. As much as the resolution is important, so does the frequency of the PWM signal. The increase in PWM resolution decreases the maximum PWM frequency possible for the same clock frequency. if UNO and ESP32 have the same clock frequency i.e., 16 MHZ. The maximum possible PWM frequency(16-bit) for ESP32 will only be 244 Hz. Whereas for UNO(8-bit), it is 62.5 KHz. For example, 16 MHz / 256 and 16 MHz / 65,536. EDIT: Hey everyone! Let’s clear up the confusion regarding PWM resolution and the difference between dividing by 2^n versus 2^n - 1 The Hardware Timer Perspective In fast PWM mode, the timer counts from 0 up to a “TOP” value and then overflows back to 0. For 8-bit PWM, TOP = 255. This gives you a counter range of 0–255 = 256 distinct counts. For 2-bit PWM, TOP = 3. This gives you a counter range of 0–3 = 4 distinct counts. Thus, in terms of raw timer ticks, there are 2^n counts per cycle. The Duty Cycle Perspective When calculating duty cycle, we typically use: Duty Cycle (%)= (Compare Register Value/TOP) ×100. For 8-bit PWM, you divide by 255 (TOP = 255), so the highest compare value 255 yields 100 % duty cycle. For 2-bit PWM, you divide by 3 (TOP = 3), so a compare value of 3 yields 100 % duty cycle. If you were to divide by 2^n directly (e.g., 256 for 8-bit), the maximum compare value (255) would give (255/256)x 100 =~ 99.6% which technically matches clock ticks but doesn’t align with the usual definition of 100 % on hardware PWM outputs. Why It Matters 0 % duty cycle: Compare Register = 0. 100 % duty cycle: Compare Register = TOP (which is 2^n - 1). Users generally expect that the maximum compare setting translates to the output being fully ON (i.e., 100 %). Summary The timer truly counts 2^n steps (from 0 to 2^n−1). However, to get a duty cycle percentage from 0 % to 100 %, you divide the compare value by 2^n - 1. That’s why for 8-bit PWM, you’ll see many references to dividing by 255, not 256. | |||||
| Answer to: How to calculate decoupling capacitor values? | 6 Relevance | 9 months ago | Neeraj Dev | Theoretical questions | |
| Decoupling capacitors are essential for stabilizing the power supply and suppressing noise in microcontroller and digital circuits. A common starting point is placing a 100 nF ceramic capacitor (X7R type recommended) close to the Vcc and GND pins of each IC to handle high-frequency transients. To support sudden current demands and filter lower-frequency noise, it's also good practice to add a bulk capacitor—typically 1 µF to 10 µF—near the microcontroller or groups of ICs. The exact values depend on several factors, including the switching speed of the ICs, current consumption, and the quality of the PCB layout. Faster ICs may require additional smaller capacitors like 10 nF or 1 nF in parallel with the 100 nF to cover a broader frequency range. High-current circuits may benefit from larger bulk capacitors up to 47 µF. Proper placement is critical—capacitors should be located as close as possible to the power pins, with short, direct traces. Using a mix of capacitor values in parallel helps improve overall decoupling performance. While 100 nF is a solid default, evaluating layout and load conditions can help you fine-tune your choices for a more robust and reliable design. | |||||
| RE: What exactly is PWM resolution ? | 4 Relevance | 1 year ago | FullBridgeRectifier | Hardware/Schematic | |
| @ankunegi The answer is on point but I think there's a mistake in your calculation. To calculate the duty cycle, we have to divide it by 255(the maximum value) and not 256(The total no. of steps). For example: A 2-bit PWM signal has 4 possible steps: 0,1,2 and 3 corresponding to 0%, 33.33%, 66.67% and 100% duty cycle. You get this by dividing by 3, not 4. If you divide it by 4, you will get 25%. Which means 0%, 25%, 50% and 75%. See, you are not getting 100% duty cycle in this case. | |||||
| Answer to: How do you safely discharge a big capacitor? | 2 Relevance | 7 months ago | CircuitSphere | Theoretical questions | |
| Firstly, don’t try to discharge a large capacitor by shorting it directly, as that can damage the capacitor and possibly hurt you. The safe WAy is to use a resistor with a suitable value (for example, 10 kΩ–100 kΩ, a few WAtts). Connect it across the capacitor terminals and let the voltage bleed off slowly. Always confirm with a multimeter that the voltage has dropped close to zero before handling the circuit. This WAy you stay safe, and the capacitor stays intact. | |||||
| Answer to: What is bandwidth in oscilloscope? | 4 Relevance | 1 year ago | Rashid | Equipments | |
| ... few key points below: Signal Accuracy: If your oscilloscope's bandwidth is too low, it will attenuate (weaken) higher-frequency components, distorting the signal shape. Capturing Fast Transients: Digital signals (like square WAves) contain high-frequency harmonics. Insufficient bandwidth causes edges to round off, making it hard to analyze fast transitions. Noise and Spikes: A higher-bandwidth scope can reveal high-frequency noise, while a lower-bandwidth scope might filter it out. A general rule is to select an oscilloscope with a bandwidth at least 5 ... | |||||
| Answer to: Difference between EEPROM and Flash? | 4 Relevance | 1 year ago | Admin | Hardware/Schematic | |
| Both are very different from each other. Here's how: Flash Memory Purpose: Primarily used to store the program (firmware) that runs on the microcontroller. Access Method: Works at the block level, meaning you write or erase data in chunks, not byte by byte. Endurance: Lower than EEPROM, typically around 10,000 to 100,000 write/erase cycles per block. Speed: Faster read speeds compared to EEPROM. Capacity: Much larger than EEPROM (e.g., Arduino Uno has 32 KB of Flash memory). EEPROM (Electrically Erasable Programmable Read-Only Memory) Purpose: Designed to store small amounts of data that need to be saved even when the power is off (e.g., device settings or user preferences). Access Method: Data is accessed and written byte by byte, making it perfect for small, frequently changing data. Endurance: It has a high write endurance, typically allowing 100,000 to 1,000,000 write/erase cycles. Speed: Slower compared to Flash. Capacity: Usually much smaller (e.g., Arduino Uno has only 1 KB of EEPROM). What is their purpose in Arduino boards? Flash Memory: This is where your Arduino sketch is stored when you upload it via the IDE. If you need to store constant data like lookup tables, you can use Flash with the PROGMEM directive. EEPROM: You can use it to store user-defined values like calibration data or device settings using the EEPROM library to store it permanently. | |||||
| Answer to: Do I really need anti-static precautions when handling ICs? | 2 Relevance | 8 months ago | Anju | Theoretical questions | |
| Yes, you do. Static electricity, even in amounts you can't feel, can permanently damage or destroy sensitive ICs. Many components, especially CmOS-based ICs, have extremely low ESD (Electrostatic Discharge) tolerance — sometimes as low as 100 volts, while a static discharge from your finger can exceed 3,000 volts. Damage isn't always immediate; latent defects caused by ESD can reduce the lifespan or cause intermittent failures later. Taking anti-static precautions like using a grounded wrist strap, anti-static mat, and proper storage methods is essential to prevent both immediate and future component failure. | |||||
| RE: What exactly is PWM resolution ? | 2 Relevance | 1 year ago | Admin | Hardware/Schematic | |
| @FullBridgeRectifier Thanks for clarifying this. To summarize, there’s a subtle but important distinction here between “how many counts the hardware timer cycles through” (which is indeed 2^n counts) versus “how you usually compute the duty‑cycle fraction” (which typically uses 2^n − 1 in the denominator so that the maximum register value maps to 100 %). I have edited my answer and added the explanation for this as well. | |||||
| Answer to: Why Does analogWrite Use a 0-255 Range for PWM? | 4 Relevance | 2 years ago | TechTalks | Programming | |
| Hello paul, In Arduino, the analogWrite function is used to generate a PWM signal on a specified pin. The value parameters ranging from (0-255) you provide determines the duty cycle of the PWM signal. Value of 0: This means the pin is always off (0% duty cycle). Value of 255: This means the pin is always on (100% duty cycle). Values between 0 and 255: These values correspond to duty cycles between 0% and 100%. For example, a value of 127 would create a 50% duty cycle. This allows for precise control of analog devices, such as LEDs or motors, using digital signals. | |||||
| Answer to: Can i use EN pins for PWM speed control in L298N Motor driver? | 4 Relevance | 2 years ago | Admin | Hardware/Schematic | |
| Yes, you can hook these pins to the PWM pin on Arduino. The Enable pin on the L298N acts as a gatekeeper for the power supplied to the motor. When the pin is set HIGH, the motor is enabled and can run. When set LOW, the motor is disabled and stops. By connecting the Enable pin to a PWM-capable pin on the Arduino and sending a PWM signal, you can control the effective voltage supplied to the motor. This changes the speed of the motor: A higher duty cycle (e.g., 100%) means the Enable pin is HIGH most of the time, allowing full power to the motor and thus full speed.A lower duty cycle (e.g., 50%) means the Enable pin is HIGH only half the time, reducing the average power supplied to the motor and thus reducing the speed. Here's an example that demonstrates how to set up and control the motor speed connected to A channel: // Define pins const int ENA = 9; // PWM pin for Motor A const int IN1 = 8; // Direction pin 1 for Motor A const int IN2 = 7; // Direction pin 2 for Motor A void setup() { // Set pin modes pinMode(ENA, OUTPUT); pinMode(IN1, OUTPUT); pinMode(IN2, OUTPUT); } void loop() { // Set motor direction digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW); // Set motor speed using PWM analogWrite(ENA, 127); // 50% duty cycle, half speed delay(2000); // Run for 2 seconds // Change motor speed analogWrite(ENA, 255); // 100% duty cycle, full speed delay(2000); // Run for 2 seconds | |||||
| Answer to: How can servo jitter be reduced in Arduino projects? | 2 Relevance | 5 months ago | Neeraj Dev | Arduino | |
| Servo jitter in Arduino projects is usually caused by power instability, electrical noise, long signal wires, or software timing conflicts. To reduce it, use a separate and stable power supply for the servo (not the Arduino 5V pin), and connect all grounds together. Add a 100 µF–470 µF electrolytic capacitor near the servo’s power pins and a small 0.1 µF ceramic capacitor for noise filtering. A 220–470 Ω resistor in series with the signal line can also help. On the software side, avoid writing the same servo position repeatedly, filter noisy input signals, and use small delays or smoothing functions to prevent rapid position changes. These steps usually eliminate most servo jitter problems. | |||||
| RE: What exactly is PWM resolution ? | 2 Relevance | 1 year ago | Sebastian | Hardware/Schematic | |
| Good point by @FullBridgeRectifier . Just to clarify for anyone new to this: when we say “divide by 255 instead of 256,” it’s because we’re looking at the maximum value the PWM can take, not the total count of values. This WAy, your duty cycle calculations always correctly reach 100%. | |||||
| Answer to: Why Does analogWrite Use a 0-255 Range for PWM? | 2 Relevance | 2 years ago | Sebastian | Programming | |
| To the point answer by Techtalks. Just WAnt to add one important point here: The PWM pins on UNO have an 8-bit resolution. This gives us 256 discrete duty cycles, since 2^8 = 256. Example: 2 bit means 4 possible duty cycles. For PWM, they would be: 0, 33.33%, 66.66%, and 100%. Similarly, 4-bit means 16 duty cycles, and 8-bit means 256 cycles. Now why does the PWM range from 0 to 255 and not 256? Because when you count 0, the total values from 0 to 255 are 256. | |||||
| Need help with the working of this circuit | 2 Relevance | 2 years ago | nathan | Circuits and Projects | |
| Hello everyone, I found this circuit in the "100 transistor circuits" ebook. Can somebody explain the working? Thank you Attachment : LED-flasher-circuit.jpg | |||||
| RE: Why Place Decoupling Caps Near ICs? | 2 Relevance | 5 months ago | xecor | Theoretical questions | |
| @electronic_god The 0.1 µF decoupling capacitor placed near an IC’s power pin serves to provide immediate energy and absorb high-frequency noise when the chip’s current demand suddenly changes. When an IC switches states, it draws a short burst of current. If that current must travel from a distant power source through long PCB traces, the inductance and resistance of those traces cause a brief voltage drop, leading to supply fluctuations or even logic errors. A small capacitor located right beside the power pin can release charge within nanoseconds, keeping the voltage stable. If the capacitor is placed farther away, the trace inductance increases significantly, and the capacitor becomes ineffective at high frequencies. In practical design, a 0.1 µF capacitor is typically used to handle high-frequency transients and switching noise, while larger capacitors such as 1 µF or 10 µF address lower-frequency voltage variations and stabilize the overall supply. Usually, each IC power pin has its own 0.1 µF ceramic capacitor to shunt high-frequency disturbances; an additional 1 µF or 4.7 µF ceramic capacitor is placed nearby to handle mid-frequency energy needs; and a larger 10 µF to 100 µF tantalum or electrolytic capacitor is located at the power input or voltage regulator output to serve as bulk energy storage for low-frequency stability. The decoupling capacitor should be placed as close as possible to both the power and ground pins of the IC, with traces kept short and wide, preferably connected directly to the power and ground planes to minimize loop area and parasitic inductance. Ceramic capacitors, especially those with X7R or X5R dielectric, are ideal for this purpose because they offer low equivalent series inductance (ESL) and low equivalent series resistance (ESR), allowing fast current response. In summary, the location of the 0.1 µF capacitor determines whether it can respond effectively to transient events, while the combination of different capacitor values defines the frequency range the decoupling network can handle. Small capacitors react quickly to high-frequency noise, and larger ones maintain steady voltage over longer timescales. Together, they ensure the IC’s power supply remains clean, stable, and reliable. Attachment : 4.png | |||||
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