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DevHeads IoT Integration Server

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PCB Design review. How did I do?

Very new to designing a PCB and want to see how well I've done. This is a Mini PCI-e card that is a mixture of the CANable USB module but in a PCI-e form for the development board I'm working with, but I've also added connections for a Beitian be-880 GPS module.
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Navigating Capacitor Choices in My Synchronous Buck Converter Design

Hello everyone. I am designing a synchronous buck converter using stm32f103c8t6 chip. I intend to use timer 1, i have setup my registers already and tested my output signals all seems fine with dead time included. I moved on to calculating the required inductance and output capacitance. I got 42uH for the inductance and the capacitance to be 73uF. I observed some designs done, and I did the calculations the capacitance falls in the same range, but they ended up using between 330uf and 470uf. I t...

Fingerprint Sensor Enrollment Failing at Image Conversion Step

hey guys, I’ve successfully initialized the fingerprint sensor using UART, but when I attempt to enroll a new fingerprint, the enrollment process fails after step 2 (converting image to template). The enrollFinger() method returns an error code FINGERPRINT_IMAGEMESS. here is my code: ```int result = finger.enrollFinger(1); // Enroll fingerprint with ID 1 if (result == FINGERPRINT_OK) { Serial.println("Fingerprint enrolled!");...

UnboundLocalError in Obstacle Detection with Ultrasonic Sensor Using MicroPython

Am working on a smart car automation system using MicroPython, the system include various functionalities such as obstacle detection, line following, speed control, and environmental monitoring. am trying to detect obstacles in front of the car using an ultrasonic sensor HC-SR04 and control the motor accordingly. my aim is to measure the distance to obstacles and stop the car if an obstacle is too close. But I keep getting the error UnboundLocalError: local variable 'start' referenced before assignment here's my code 👇 ...

Troubleshooting Frequency Dropout Issues in Instrument with Photodetector

Hello, I am working with a instrument where we frequently get the problem of frequency drop out, i.e. suddenly frequency signal goes missing i.e. goes to zero, this cause the loss in data as shown in the below image. Yellow is received frequency signal from Photodetector and Purple is the demodulated data (our desire output). When frequency goes zero the purple line is constant so data is lost. Can you help me find a solution for this problem!...
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Connecting 12V WS2815 LEDs to Arduino Nano: Do I Need Any Precautions to Ensure Safe Operation?

Hi everyone, I am building a light cube using WS2815 individually addressable LEDs, which are powered at 12V. There are almost 700 LEDs in total but only max 50 will light up simultaneously. Using an Arduino Nano to drive the strips, with wiring diagram as shown here. As shown in the diagram, I am using a power supply that gives both 5V and 12V. I am connecting the GND of the B channels on the LED strips to GND. I think I should also connect the GND from the 5V and 12V power supplies to make sure they have the same reference voltage. My question: do I need to add any precautions anywhere to avoid my Arduino from getting fried or the LED strips from working as intended ?...
Solution:
I suggest based on the diagram that you can add a current limiting resistor to reduce the amount of current going to the nano chip so it won't be very much. Then try to calculate the total power that is required to turn on all the led. It seems the total current needed is insufficient to power the 70 led. I suggest you increase the current of the D-60A power supply little bit further....
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How to Interface a 4-Wire Vacuum Suction Motor from a Vacuum Robot with a Raspberry Pi?

This is a vacuum suction motor from vacuum robot that am trying to interface with Raspberry Pi. It has 4 wires and am not able to get it working. Any suggestions on wiring
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How to Interface an Industrial TDS Electrode with Arduino to Read and Display mV Values?

hey guys i bought a Industrial grade conductivity electrode (TDS ) , it has 3 pin ( +ve , gnd , output ) . It returns me value in mV . My application needs to read the electrode using arduino and display its value on serial monitor . Asper online sources i need a circuitry to help me read the value . Can anyone help me with it
Solution:
You can use this guide here. Majorly when measuring voltage using Arduino you will need an ADC. For this guide each unit of the 1023 bit is equivalent to 4.9mV when using the Arduino. https://www.google.com/amp/s/www.instructables.com/Voltage-Measurement-Using-Arduino/%3famp_page=true...

Designing an SDR with PoE Power Supply: Synchronizing SMPS and Managing Heat and Noise

Hey all! Background at the start, I invite comments on it but core questions are at the bottom 🙂 Primarily an embedded sw eng who dabbles a bit in hardware from time to time. I've always wanted to make an SDR and have been hashing out a high level design for one - it boils down to some ECP5 FPGA based board, gigabit etherenet, a DRAM chip, all powered by PoE with some SDR payload. The SDR payload is still a little open, I will either use something integrated like AT86RF215 or use a mixer + ADC - one thing for certain is I will include a MAX2769 for messing about with GNSS signals to try and extract very accurate timing information (this is the core goal, based on some other SDR projects I played with in the past) Just now I have been looking at how to power the system. For PoE I found several reference designs with LM5070 and plan to use that for the main PSU....

Designing a Type-C Charger with 12V Input for Phone and Laptop Charging

I want to design a charging system that has type c output port. The charger will have its supply from a 12v battery. I want the type c to charge my mobile phone and can also charge my laptop. I know i am going to need a PD ic probably STUSB4500, FUSB302, or TPS25750. My challenge now is i am trying to wrap my head around the voltage levels, for example my phone will require 5v to charge, my laptop will require 18.3v or there about to charge. Will i have to design a buck converter that can step down to 5v and also a boost converter that can boost 12v to 18.3v for the laptop? How will the PD switch between the boost converter and buck converter as needed? What IC can be recommeneded to use? I would appreciate help and directions on this project. If more information is needed i can drop more information....
Solution:
You will need a buck converter (5V for phone), boost converter (18.3V for laptop), PD controller, and power multiplexer. The PD controller negotiates voltage, while the multiplexer switches between converters. Consider TPS62903 (buck), LM2733 (boost), and TPS65987D (multiplexer) as potential ICs. The system will dynamically adjust output based on the connected device's requirements.

Check Out My New Mini MIDI Controller Prototype – Any Tips on Design or Control Ideas?

My latest WIP, the "World's Second Smallest MIDI Controller" (I think). It's a bit bigger than the first iteration https://www.youtube.com/watch?v=5Ws_JfCw5NY in order to accommodate a potentiometer and larger buttons, as well as a CR2032 battery instead of a CR2016. I also added an ICSP header pinout with the extra room, which is an absolute treat to flash versus using a chip clip, at least in my initial LED flashing test. Also used some better solder paste and possibly heated it to a better temperature and things seemed to melt into place MUCH better. Cool making a 2nd prototype of something and getting to correct some of your errors! If any of you are musically inclined (or even if you're not) any suggestions on how to actually use it controls-wise? I have some ideas, but good to get other perspectives!...
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Incorrect Battery Percentage Reading on MKR 1010 with 3.7V Lithium Battery

Hi I am using the following code to monitor a 3.7V 800MAH lithium battery to power my MKR 1010, and I have all the required library. However, this code always shows the battery percentage as 100, do you have any idea how to solve? ``#include "Battery.h" Battery battery(2750, 4200, ADC_BATTERY);...

SWV printf Output Issue in C++ on STM32G431KB

I am currently utilizing an STM32G431KB board that differs from other boards in the STM32 Nucleo series as it has a wired SWO. While setting up SWV printf on a Nucleo variant of the same product, I encountered an inquiry and implemented suggestions given by its first answer which allowed me to enable functioning SWV under C programming language. However, upon switching over to C++, no output is visible during usage of this feature. For the C project, I created a new project, switched Debug to "Trace Asynchronous SW," and added the following code: ...

Measuring Current Consumption on STM32 Nucleo-64: JP6 Jumper Behavior and Ammeter Use

Hi guys, how can I properly measure the current consumption of the microcontroller on my STM32 Nucleo-64 evaluation board (NUCLEO-L073RZ)? The manual instructs me to remove the JP6/IDD jumper and connect an ammeter in series between the pins to measure the current. However, when I remove the JP6 jumper without connecting the ammeter, the microcontroller continues to operate, allowing me to debug and communicate via I2C. I expected that removing the JP6 jumper would cut the power to the microcontroller, making it inaccessible unless an external power supply was used. ...
Solution:
Connect the ammeter in series between the two pins of JP6. This allows you to measure the current flowing directly into the MCU's VDD line, which represents the power consumed by the MCU and any connected peripherals powered from VDD.

Should I Connect the 120Ω Resistor on UART-to-RS485 Converter for 2-Module Communication?

Hello, Got a uart-to-rs485 converter board from the AliExpress . Its schematic is very close to this one...
Solution:
I would say you should not short it. Leave it open as it is in the schematics diagram. If it's a Uart line then it shouldn't have an issue. But I would say you should check the datasheet and confirm what the manufacturer said about this.
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MOSFET Heating Issue in Boost Converter with SG3525 and IRFB4110

I am working on a boost converter to step up DC voltage from 12v to 450v. My switching frequency is 45khz on each channel of the sg3525. I am using irf3205 as my switch. I observed that when i change the switches to another MOSFET like irfb4110 of higher rating the switch/MOSFET gets heated up even with no load at the output, has anyone faced similar issues before? my gate resistor is 10R and my gate to source resistor is 10k
Solution:
Read the datasheet of the mosfet, it seems like the current rating is less than it can handle, thereby causing the IRF4110 to overheat. And also check the resistor value required, i suggest you increase the resistance so there will be less current flow to the mosfet

Feedback on MIDI-to-Arduino Adapter Circuit Before Testing?

Working on a MIDI-to-Arduino et al adapter. Not the hardest circuit in the world, and easy enough to breadboard, but might be useful for some. Any comments so far? Guess I should breadboard it and test it out.
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Logic for Sensor Measuring Natural Water Rise and Surface Pressure in a Well Setup?

hey what should be the logic behind a sensor which calculates the - natural rise of water above the sensor level, showing how much pressure drives the water to the surface. ( in a well like setup)
Solution:
The sensor measures the pressure of the water above it. The higher the pressure, the higher the water level. The sensor calculates the height of the water level based on this pressure. Pressure = Water Height The sensor uses this equation to determine how much pressure is driving the water to the surface, and thus calculates the natural rise of water above the sensor level....

Why Does My ATTiny85 Analog Input Return a Constant Value After 24 Hours?

Hi, I’m trying to get the value of my battery using an analog input of my ATTiny85 to create a gauge. To do this, I made a voltage divider to avoid draining too much battery. The problem is that I don’t understand why, after letting my project (which includes sensors and a screen) run for more than 24 hours, I’m still getting an input value of 512 with an analogRead(). I haven’t applied any calculations yet, just retrieving the value from my voltage divider. But this value doesn’t budge at all... I’m using a 3.7V 400mAh LiPo battery....
Solution:
Related to that, I would highly recommend using the TinySnore library if you're concerned about optimizing power usage. I used it in another project that uses a CR2016 battery and it's able to run for ~a few weeks using intermittent monitoring of inputs: https://embeddedcomputing.com/technology/processing/chips-and-socs/tinysnore-turns-your-attiny-into-a-low-power-prodigy (granted, my device is just sitting there most of the time)

Is it possible to use this MAX30102 heart rate sensor to detect a heart attack?

Hi there, right now I am planning to make a device which can detect a heart attack by using MAX30102 After a small research, I found out that a heart attack may be caused by a sudden increase in heart rates or the SpO2 level (the amount of oxygen that your blood is carrying) is lower than 90%. So my question is: Is it possible to use this MAX30102 heart rate sensor to detect a heart attack?...
Solution:
The MAX30102 sensor is great for measuring heart rate and SpO2, but using it to detect a heart attack isn’t straightforward. Heart attacks involve more than just changes in heart rate or oxygen levels, so relying on this sensor alone wouldn't be enough for accurate detection. But I think that AI can help because it can analyze heart rate and SpO2 patterns over time to spot anything unusual. But to reliably detect a heart attack, you'd need more data, like ECG readings or other health metrics....
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