write lib for sx1278

Hi everyone,
I’m trying to initialize the SX1278 LoRa module directly from the datasheet, but I’m having trouble figuring out which registers I actually need to set and in what order. The datasheet lists a lot of registers and parameters, but it doesn’t explicitly say which ones are required for basic initialization.

Can someone point me to the specific sections/pages in the official datasheet that explain how to set up the module for LoRa mode, frequency, spreading factor, bandwidth, preamble, and TX/RX mode? I want to understand this directly from the documentation rather than relying on example code.

https://redd.it/1pyqs3p
@r_embedded

Troubles with entering the bootloader of the CH32V203

Hi everyone,

I have just recently seriously started my journey into embedded electronics. Part of my project requires making a fully functioning development board based on the CH32V203(C8T6) SoC. I've designed a PCB, gotten it manufactured, and soldered the components. Fortunately, it worked and I could see the chip appear on my `lsusb` list. I've spent ages trying to write code onto it (I ended up making my own C program for that).

It worked - I wrote a blinky and even drove an 8-bit LED array with cool patterns. Then, I went to sleep and woke up. The chip no longer wanted to appear as a USB device on my PC.

Here is some interesting behaviour I noticed:
I hold BOOT0 and press RESET. The chip resets, good. Then, as soon as, and only *after*, I let go of BOOT0, the LED program starts instead of the bootloader. Even while BOOT0 is held, no appearance of it as a USB device.

I investigated and though that maybe it was the external crystal at fault (I wired it up wrong) so I re-soldered it diagonally. Nope.

I even spent a day soldering another board (of the same design) and that works! Still, I would like my first board to work as well in case this issue arises on the second one as well.

I couldn't have fried it while soldering as it broke overnight. Maybe I pushed too much current? But why do the LEDs work then and not the bootloader?


Unfortunately, I do not have the WCH-Link to debug over SWIO and I don't have a seller close by. What do I do?


Thank you!

https://redd.it/1pyv5da
@r_embedded

BinForge – Post-Build ESP32 Firmware Tool & Framework for Injecting Data
https://redd.it/1pyu9fx
@r_embedded

What to learn Zyphr Rtos or Embedded linux driver development?

I am fairly new to embedded systems, though I have experience with STM32 and FreeRTOS. Whenever I search for embedded development roles on job portals, I frequently see Zephyr RTOS mentioned. Other job profiles specify Embedded Linux driver development. Does embedded driver development align with the profile of an embedded developer? Furthermore, should I focus on learning Embedded Linux development or Zephyr RTOS first?

https://redd.it/1pyx17c
@r_embedded

Wokwi based design for Rohee Desktop gadget robot with ESP32-C3

This is the link for online based design.
https://wokwi.com/projects/450256201969103873

https://redd.it/1pyxu7a
@r_embedded

How to get smooth velocity reading from incremental angle sensor?

Hi,

I am using my teensy4.0 and the MT6835 magnetic encoder to measure the incremental angle (65536 CPR) of a rotating motor shaft.

Context: I want to build an rotary inverted pendulum and therefore have to measure the angle of a motor shaft and a pendulum shaft and also the angular velocity respectively.
I don’t expect big velocities but rather how accelerations because of fast direction changes . The will be no state of constant rotation. So I need very accurate velocity data.

I configured two pins on my teensy4.0 to detect incoming encoder pulses and trigger an interrupt. Basically what i want to do is to measure the time between each encoder pulse by using a timer on my teensy. By doing so I get a value which is inversely proportional to the shaft rotation speed.

I am also using another method where I count the encoder pulses within a fixed time interval and then derive the shaft speed from it.

Combining these two methods to change between high speed and low speed works kind of good.

But sometimes there are some spikes in my velocity reading and sometimes the reading does not really work.

Does anyone know of there is a library for reading encoder pulses and simultaneously measure the time between each encoder pulse ?

Does anyone know if there is a better way to do it ? Or do you have good tips for me?

I can send my code, if needed:) thank you !!

https://redd.it/1pz21eh
@r_embedded

Interview coding languages

Are intern interviews typically done in C or C++. This past cycle I had interviews in both and each time I asked what language to focus on both interviewers said it depends on the company. I’ve been practicing some leetcode in C++ but was wondering if that’s the wrong decision since c++ gives access to new data structure not in C.

https://redd.it/1pz39r2
@r_embedded

ESP32 SD Card Module Not Mounting Card

I am trying to get a MicroSD card adapter to work with my ESP32 DevKit-V1, but I can't happen to get it working. I've gotten the same module to work with an Arduino Uno on 5V, but I cannot get it to work with my ESP32. Code is below, but here are my troubleshooting steps.

I'm using a cheap HW-125 SD card adapter with my ESP32 DevKit-V1 with the following pinout:

* CS - D5
* SCK - D18
* MOSI - D23
* MISO - D19
* VCC - 3.3V
* GND - GND

Troubleshooting steps I've tried

* I tried a second HW-125 to ensure I didn't burn the first one
* Re-formatted the 8GB SD card to FAT32 using official SD formatter tool
* Tried connecting VCC to a 5V source instead of the 3.3V (with a common ground)
* Tried changing the GPIO pins
* Tried changing the card speed in the code from 4MHz to 7.5 MHz to 0.4 MHz
* Ensure my card appears when plugged into a computer

Only other think I can think of is running all wires through a level shifter to 5V. I'm completely lost and appreciate any help.

In addition to this code, I've also tried the example code in the Arduino IDE library.

#include "FS.h"
#include "SD.h"
#include "SPI.h"


#define SD_CS 5 // This is the correct CS pin for VSPI on DevKit-V1


// Create an SPI class instance on the VSPI bus (default for your board)
SPIClass spi = SPIClass(VSPI);


void setup() {
  Serial.begin(115200);
  delay(2000);
  Serial.println("=== Testing with Default VSPI Pins ===");


  // Initialize SPI bus. Use -1 for the hardware SS pin.
  // SCK=18, MISO=19, MOSI=23, SS=-1 (not used)
  spi.begin(18, 19, 23, -1);


  // Initialize SD card with the defined CS pin
  if(!SD.begin(SD_CS, spi, 7500000)) {
    Serial.println("Card Mount Failed");
    return;
  }
  Serial.println("SUCCESS: Card initialized.");
 
  // Optional: List root directory to confirm communication
  listDir(SD, "/", 0);
}


void loop() {
  // Nothing here
}


// Helper function to list directory contents (optional)
void listDir(fs::FS &fs, const char * dirname, uint8_t levels){
    Serial.printf("Listing directory: %s\n", dirname);
    File root = fs.open(dirname);
    if(!root){
        Serial.println("Failed to open directory");
        return;
    }
    if(!root.isDirectory()){
        Serial.println("Not a directory");
        return;
    }
    File file = root.openNextFile();
    while(file){
        if(file.isDirectory()){
            Serial.print("  DIR : ");
            Serial.println(file.name());
            if(levels){
                listDir(fs, file.name(), levels -1);
            }
        } else {
            Serial.print("  FILE: ");
            Serial.print(file.name());
            Serial.print("  SIZE: ");
            Serial.println(file.size());
        }
        file = root.openNextFile();
    }
}

https://redd.it/1pz6nc0
@r_embedded

Emulating EEPROM on STM32 when using Simulink hardware support

https://preview.redd.it/fny5c8sj29ag1.png?width=2878&format=png&auto=webp&s=37544cfc8318ba2948fa3d36f8d9cd6e9e96b538

To make vehicle control unit (VCU) development more accessible to people who are not embedded programmers, we decided to use Simulink STM32 hardware support.

One limitation of Simulink is that you don’t have much control over low-level memory operations. Because of that, I had to write custom C functions and import them as Simulink blocks to emulate EEPROM using the last sector of the STM32 flash memory.

This implementation is used to latch error flags and store them persistently:

* Each error is written to the next available bit
* The flash sector is only erased when it becomes full, minimizing erase cycles
* Errors remain stored across power cycles until the memory is cleared

If anyone is facing a similar issue with Simulink + STM32 and needs non-volatile storage, I’ve put a working example on my [GitHub](https://github.com/Sdeslo/EEPROM-emulation-for-STM32).

Feedback and improvements are welcome!

https://redd.it/1pz5px4
@r_embedded

Chording keyboard project like MicroWriter of 80s

I am researching on MCUs alot in order to make meself a chording keyboard. I want to work using C and make a copy of microwriter MW4 and make it able to edit on the windows.
I need help on getting started for this project. From firmware to Hw and driver for this... I really need help and i am unable to find on the internet so please mention sources if possible too

https://redd.it/1pz8la3
@r_embedded

Issue reading data using CAN communication

I am student ,building E go karts in university along with my team , we need to keep a display to see operating voltage ,temperature of mosfet and motor ,soc ,speed of the vehicle in display ,which will be mounted below steering for driver. so the issue here is neither of them worked in CAN communication , so we are a bit clueless where to start.
my motor controller has an dedicated 4 pin can jsd port (5v,gnd,can_high,can_lo) and also has usb port as well and my battery also has can wires coming out of the casing(just 2 wires not marked).

As far as i searched online first ,am i supposed to read dbc file from controller and battery seperately in my laptop ? , then write code acc to display them in a display . Now to read data in laptop which software i should use Pcan or canalyser or vesc ?( my controller vendor suggested pcan, but i hv no idea of that and i use to vesc to tune my motor),now what hardware i might require to read from my controller and battery , like can to usb modules?, or can transeiver or something else . Even with wiring part i just now that can bus should be truncated with 120 ohm, is there anything i should know?
so can u guys share your thoughts, ideas and knowledge on this

https://redd.it/1pza99r
@r_embedded

STM32F042 USB-C Module — Schematic Review Before PCB Layout (2-Layer)
https://redd.it/1pzeyvx
@r_embedded

STM32U5 OctoSPI Quad Mode (IO4–IO7) + W25Q128 works, but XIP memory-mapped mode doesn’t

I’m using STM32U5 OctoSPI with Winbond W25Q128 QSPI NOR.

Setup:
OctoSPI in Quad mode
IO0–IO3 remapped to IO4–IO7
Indirect mode works fine:
JEDEC ID read OK
Read / write / erase OK

Problem:
Memory-mapped mode (XIP) doesn’t work
Invalid data / faults when trying to execute or read via mapped address

Looking for:
How to properly configure memory-mapped mode on STM32U5?

Any tutorials, app notes, or example projects
Any known gotchas when using Quad mode on IO4–IO7 for XIP.

Is XIP officially supported in this configuration, and are there any special settings (dummy cycles, opcode, cache/MPU config, etc.) I should be aware of?

Thanks!

https://redd.it/1pzj852
@r_embedded

where/how do you get small quantities of chips for new projects without shipping being the majority cost?

just that, any little project I look at doing now, I start to go , why bother, when amazon has the entire thing built for much cheaper. and the chips for a custom board, well then that's a different more expensive path.

I miss the cheap digikey days, with samples..or even free shipping aliexpress. I'm not one to plan for bulk orders

https://redd.it/1pzn375
@r_embedded

Very Confused about this module

Guys I recently i bought this ADC the datasheet of the AD7606 of Analog and the ADC module is different which makes me very confused , I surfed throught i only find the parallel connection only. If some used this module help me through it ,if you find this module schematic or any tutorial or you already used help out guys.

https://redd.it/1pzod7m
@r_embedded

Designed and assembled a camera controller board based on ESP32-P4 with PoE support (50x60mm). Also, optional edge TPU support. How does it look?



Note: I have to correct those solder blobs in the ESP32-P4 chip.

Note: Will correct those solder blobs in the ESP32-P4 chip.

https://redd.it/1pzw666
@r_embedded

Looking for a tool to measure overall consumption, inrush & peak currents and multiple analog voltages

Hey everyone,

I’m working on embedded/smart products with lots of on/off loads, soft starting, and switching rails, and I’m looking for a measurement tool that can help me with a few key things:

Measure overall power consumption (voltage + current)
High enough sample rate to capture inrush and peak currents accurately
Multiple (3+) analog inputs so I can monitor several voltage rails ramping up at the same time
Synchronous data (so voltage and current are aligned on the same timeline)

I’ve come across the Joulescope JS220, which is great, excellent current accuracy and sampling rate, but it only has one analog voltage input, which isn’t enough for my use case.

Do you have any other measurement tools you would recommend that are similar to Joulescope JS220 but with more analog input?


Thanks!

https://redd.it/1pzvkgi
@r_embedded

Foreign Computer engineer

Hi everyone,

I am moving soon to the US and I will be a green card holder so I won’t be needing a work visa. I have a degree in computer engineering from the Middle East and was wondering how hard it is to find a job at the US, if possible at all?

what process do foreign engineers follow in order to get a job?

https://redd.it/1pzy0yx
@r_embedded

SoM for wearable applications
https://redd.it/1q00oof
@r_embedded

Embedded Languages

What are all the programming languages that we can use to program a Embedded systems other than C/C++ ? I know Cpp and PY, did you use any other languages than C/C++ ?

https://redd.it/1q03hj9
@r_embedded

RPi 4 (4GB) edge face recognition (RTSP Hikvision, C++ + NCNN RetinaFace+ArcFace) @720p, sustainable for 24/7 retail deployments?

Hi everyone. I’m architecting a distributed security grid for a client with 30+ retail locations. Current edge stack is Raspberry Pi 4 (4GB) processing RTSP streams from Hikvision cameras using C++ and NCNN (RetinaFace + ArcFace).

We run fully on-edge (no cloud inference) for privacy/bandwidth reasons. I’ve already optimized the pipeline with:

Frame skipping
Motion gate (background subtraction) to reduce inference load

However, at 720p, we’re pushing CPU to its limits while trying to keep end-to-end latency < 500ms.

# Question for senior engineers

In your experience, is the RPi 4 hardware ceiling simply too low for a robust commercial 24/7 deployment with distinct face recognition?

Should we migrate to Jetson Nano/Orin for the GPU advantage?
Or is a highly optimized CPU-only NCNN pipeline on RPi 4 actually sustainable long-term (thermal stability, throttling, memory pressure, reliability over months, etc.)?

Important constraint / budget reality: moving to Jetson Nano/Orin significantly increases BOM cost, and that may make the project non-viable. So if there’s a path to make Pi 4 work reliably, we want to push that route as far as it can reasonably go.

Looking for real-world feedback on long-term stability and practical hardware limits.

https://redd.it/1q050vd
@r_embedded