[New Variant] STM32F103C8T6 with DX-LR30 or DX-LR20

[g6094199]

Board description (please complete the following information):

• Name: [e.g. DISCOVERY F769NI]
• Link to all relevant information:
  • Documentations
  • Schematics
  • Where this hardware can be purchased

• ...

I found and ordered some OEM dev boards from a chinese manufacturer on aliexpress.
these have a STM32F1 combined with a LoRa module on one board, which makes them very interesting for long therm low energy LoRaWAN applications.

and i would be happy to donate a board to an interested developer!

STM32F103C8T6 & DX- LR30 (Semtech SX1262)

DX-LR20-900M22S Module technical manual .pdf
DX-LR20-900M22SP Development board user_s manual.pdf
LR20-SP PCBA schematic diagram.pdf
DS_LLCC68_V1.0.pdf
STM32F103C8T6.pdf

and its brother, which is NOT 100% LoRaWAN compatible and has some cavecats while using TheThingsNetwork

STM32F103C8T6 & DX- LR20 (Semtech LLCC68)

[fpistm]

Added to #722

[olek87]

you have to set DTR and RTS write to get the board in flash-mode. I made (rather gpt did) a small script for visual studio code. it works dor me, maybe someone finds it useful:

reset.sequence.py:

Import("env")
import serial
import time
import serial.tools.list_ports

def get_upload_port(env):
    """Ermittelt den Upload-Port"""
    port = env.subst("$UPLOAD_PORT")
    
    if not port or port == "":
        ports = list(serial.tools.list_ports.comports())
        if ports:
            port = ports[0].device
            print(f"Auto-detected port: {port}")
        else:
            print("⚠️ No COM port found!")
            return None
    
    return port

def custom_reset_sequence(source, target, env):
    port = get_upload_port(env)
    if not port:
        return
    
    print(f"🔄 ISP Boot Sequence on {port}...")
    
    try:
        ser = serial.Serial(port, 115200, timeout=1)
        
        ser.setDTR(False)  # DTR LOW = Reset
        ser.setRTS(True)   # RTS HIGH = Boot0
        time.sleep(0.1)
        
        ser.setDTR(True)   # Reset freigeben
        time.sleep(0.05)
        
        ser.close()
        print("✅ Reset sequence complete!")
        
    except Exception as e:
        print(f"❌ Error: {e}")

def reset_after_upload(source, target, env):
    port = get_upload_port(env)
    if not port:
        return
    
    print(f"🔄 Resetting device on {port}...")
    
    try:
        ser = serial.Serial(port, 115200, timeout=1)
        
        ser.setDTR(False)  # DTR LOW = Reset
        ser.setRTS(False)  # RTS LOW = Normal Boot
        time.sleep(0.1)
        
        ser.setDTR(True)   # Reset freigeben
        
        ser.close()
        print("✅ Device reset complete!")
        
    except Exception as e:
        print(f"❌ Error: {e}")

env.AddPreAction("upload", custom_reset_sequence)
env.AddPostAction("upload", reset_after_upload)

And this is the correspondning platformio.ini:

[platformio]
default_envs = genericSTM32F103C8

[env:genericSTM32F103C8]
platform = ststm32
board = genericSTM32F103C8
framework = arduino

upload_protocol = serial
extra_scripts = pre:reset_sequence.py

monitor_speed = 115200

build_flags = 
    -D SERIAL_UART_INSTANCE=1
    -D PIN_SERIAL_RX=PA10
    -D PIN_SERIAL_TX=PA9

[NeutralSystem]

Full working project with these boards [PlatformIO]:

https://github.com/NeutralSystem/STM32_DX-LR20_LORA

[SurejSureshLMIC]

Using DX-LR30
When plugged in I am getting
Windows Device Manager: "Unknown USB Device (Device Descriptor Request Failed)"

[g6094199]

Using DX-LR30 When plugged in I am getting Windows Device Manager: "Unknown USB Device (Device Descriptor Request Failed)"

i think u reply to @NeutralSystem ?
if u have found an bug you should file an issue over there

[NeutralSystem]

Using DX-LR30 When plugged in I am getting Windows Device Manager: "Unknown USB Device (Device Descriptor Request Failed)"

Thank you for tagging me @g6094199 .

This i will think, must be a driver issue.
Have you installed the correct drivers to communicate with the board?
to be clear, this is the driver you want: CH341SER [ https://learn.sparkfun.com/tutorials/how-to-install-ch340-drivers/windows-710 ] or, [ https://www.wch-ic.com/downloads/ch341ser_exe.html ]

[SurejSureshLMIC]

I changed to a linux laptop.

DEBUGGING:
STEP 1) took two identical boards
STEP 2) Flashed blink code on SAMPLE A using following platformio.ini

//____________________________________________________________________________
[env:blink_test]
platform = ststm32
board = genericSTM32F103C8
framework = arduino
; No external LoRa libraries - using custom driver in lib/SX1262_Custom
upload_protocol = serial
upload_speed = 115200
monitor_speed = 115200
; Output Intel HEX format for flashing with MCU ISP tools
board_build.mcu = stm32f103c8t6
board_upload.maximum_size = 65536
build_flags =
-D HAL_UART_MODULE_ENABLED
-D ENABLE_HWSERIAL1
upload_flags =
-i
rts,-dtr,dtr:-rts,-dtr,dtr
//___________________________________________________________________

code uploaded sucessfully.

STEP 3) Repeating step for SAMPLE B

        a) issue noted: ls /dev/tty* not showing /dev/ttyUSB0
        b) solution: hold down the key1 and the RST button 
        c) Result: /dev/ttyUSB0 Visible
        d) Repeat the upload process 
        e) Recieved following error msg:-

//________________________________________________________________________

Auto-detected: /dev/ttyUSB0
Uploading .pio/build/blink_test/firmware.bin
Error probing interface "serial_posix"
Cannot handle device "/dev/ttyUSB0"
stm32flash Arduino_STM32_0.9
Failed to open port: /dev/ttyUSB0
//__________________________________________________________________________

STEP 4) hold down the button while uploading

//__________________________________________________________________________

Auto-detected: /dev/ttyUSB0
Uploading .pio/build/blink_test/firmware.bin
Failed to init device.
stm32flash Arduino_STM32_0.9

http://github.com/rogerclarkmelbourne/arduino_stm32

Using Parser : Raw BINARY
Interface serial_posix: 115200 8E1

*** [upload] Error 1

//__________________________________________________________________________

STEP 5) Hold down the button and release it just before the upload started => Upload Sucessful :)

STEP 6) Plug it back in to see if it appears without holding the buttons. And it Did !!!!!!!!!!!!!!!

Problem Solved!!!!!!!!!!

But the issue still bugged me
So I found the guy who used the board earlier.
enquired about the last code which was uploaded to the board.

Apparently he used Serial.print instead of serial1.print.
Also he had was using the 'SX1262_Custom' from @NeutralSystem and CANbus code from STM32_CAN.
I believe something in that code messed up something. Unfortunately, the code was not available.

Thank you very much guys for the prompt reply.

[NeutralSystem]

I changed to a linux laptop.

DEBUGGING: STEP 1) took two identical boards STEP 2) Flashed blink code on SAMPLE A using following platformio.ini

//____________________________________________________________________________ [env:blink_test] platform = ststm32 board = genericSTM32F103C8 framework = arduino ; No external LoRa libraries - using custom driver in lib/SX1262_Custom upload_protocol = serial upload_speed = 115200 monitor_speed = 115200 ; Output Intel HEX format for flashing with MCU ISP tools board_build.mcu = stm32f103c8t6 board_upload.maximum_size = 65536 build_flags = -D HAL_UART_MODULE_ENABLED -D ENABLE_HWSERIAL1 upload_flags = -i rts,-dtr,dtr:-rts,-dtr,dtr //___________________________________________________________________

code uploaded sucessfully.

Glad it worked for you, good job.

This is my platformio file, with upload flags i figured from the documentation from the supplier of these boards, this just uploads the code to the board without needing to do anything else, ( The same as you ) using platformIO:

[env:genericSTM32F103C8]
platform = ststm32
board = genericSTM32F103C8
framework = arduino
upload_protocol = serial
upload_port = COM5
upload_speed = 115200
monitor_speed = 115200
monitor_port = COM5
; Output Intel HEX format for flashing with MCU ISP tools
board_build.mcu = stm32f103c8t6
board_upload.maximum_size = 65536
build_flags =
-D HAL_UART_MODULE_ENABLED
-D ENABLE_HWSERIAL1
upload_flags =
-i
rts,-dtr,dtr:-rts,-dtr,dtr

[g6094199]

@NeutralSystem

i´ d like to create a PR for this board to add support. but this is way more complicated (the instructions are not clear in every step and not fully created) than i thought. do we have a chance to work together on this?

[NeutralSystem]

@g6094199

You may use it/do as you wish.
What project were you thinking of? what were you thinking of achieving?