capnbry / crservof

CRSF to PWM Servo converter for STM32F103

I'm CapnBry, full name Cap'n Bry, or CapnBree or CapnBarry depending on your pronounciation. I created the HeaterMeter wifi BBQ controller project and am an ExpressLRS developer.

• I like to make things
• I am tired of explaining code to people who I'll never hear from again

crservof's Issues

Servos not working

Bluepill STM32F103C8 is connected to a HM EP1 RX.
TX to RX and vice versa UART connection.
EP1 communicates by CRSF with the 2.4 TX as I get nice 1RRSi values on the TX.
By ST-Link V2 I uploaded the firmware.bin file created from the PIO F103_serial folder by Platformio.
For uploading I used the ST32CubeProgrammer.
Program says upload succeed.
Yet I get no servo movement.
During programming the yellow BOOT pins I did not change as it is not mentioned although many YT videos show this with UART connection. But with the ST-Link it seems not needed, but I could be totally wrong. I also tried it with BOOT1 in HIGH mode, but same thing.

What more can I do?

SBUS output

Many fixed wing flight controllers require SBUS as an input. Can you add a change to output SBUS?

Thank you for your work on an ELRS converter.

PPM output support

I'm looking for something that could convert CRSF to PPM. Is this doable with this project

CRSF frame sanity check incorrect.

From the TBS spec, "Frame Length: ... Valid range is between 2 and 62 ...".

But:

CRServoF/lib/CrsfSerial/CrsfSerial.cpp

Line 86 in d5e739f

if (len < 3 || len > CRSF_MAX_PACKET_LEN)

and:

CRServoF/lib/CrsfSerial/crsf_protocol.h

Line 15 in d5e739f

#define CRSF_MAX_PACKET_LEN 64

CRSF 'FrameLength' field != CRSF BUFFER SIZE / CRSF_MAX_PACKET_LEN.

Add telemetry support for sensors

Hello,
I really like this project and would like to know if it is possible to add telemetry support, in order to send either digital or analog signals back to the transmitter.
There could be a lot of use: voltage or current sensor, barometer, GPS...
Thanks for your support,

Suggestion: Armed state LED indicator

Hello!

I think there can be a good idea if you add the LED output in case the CH5 is at high state (~2000ms).
This could be useful to indicate visually that the device is at the armed state.

Thank you.

add USB HID Joystick Support

Is there interest in adding a feature similar to the HID Joystick Support found in betaflight 3.4+?

I am not expecting there will be enough desire to yield implementation.

Thank you for building this @CapnBry,
-p

Can this code working on arduino?

If arduino nano or micro can do this?

add PPM output option

any interest in adding PPM output instead of PWM?
a lot of us still have old flight controllers like APM,mini APM,CC3D and alikes which can be use with PPM inputs only.
although these are old flight controllers but i believe they are all still well capable and stable, the only missing right now is the converter CRSF to PPM output.
Hopefully can bring back these old flight controllers in service with your CRSF to PPM output converter.

thanks.

sbus/cppm

Would you be able to make one with an sbus or cppm output?

Does not work with SoftwareSerial on atmega328

Hi, i am trying to use this library on Arduino pro mini with EP2 ELRS receiver. The small form factor of EP2 would be very good for making a lightweight flightcontroller.
to make it work, I had to change the library to SoftwareSerial, and use baud rate of 152000. However only about 70% of the channel readings are correct, and also channels are read only every 10seconds.... attached a screenshot of debug messages I added.

Is there a chance to make it work?

Target for CJMCU1038 - Purple Pill

I have some of these Purple Pill boards lying around:
https://stm32-base.org/boards/STM32F103C8T6-Purple-Pill.html
My Idea was to use them for your project, as they are small and have a proto area which makes it easy to solder a 6x3 Pin Header for the Servos.

I tried to make a new Target for the board using the pins that are broken out on the board.

#elif defined(TARGET_CJMCU1038)
      #define DPIN_LED        PB_11
      #define LED_INVERTED    1
      #define APIN_VBAT       PB_0
      #define USART_INPUT     USART1  // UART1 RX=PA10 TX=PA9
      #define OUTPUT_PIN_MAP  PA_0, PA_1, PA_2, PA_3, PB_3, PB_2, PB_1, PA_4 
 #endif

I am able to compile and flash the code, it seems to connect to the receiver but i don't get the right servo outputs.
I enabled some printlines in your code and the serial console says:

ADC=0 0V
ADC=0 0V
6666
�␌␔␀␀␀␀␀␄␀␀␀␀��␌␔␀␀␀␀␀␄␀␀␀␀ADC=0 0V
ADC=0 0V
ADC=0 0V
ADC=0 0V
tentative conn
30dBm

And then it seems stuck.

On pins PA_0, PA_1, PA_2, PA_3 i can see a 50Hz servo signal with 1700ms. The other pins show nothing.
I guess its some problem due to the used timers for my pins that need to be changed. Maybe you can point me in the right direction.

Thanks a lot
Johannes

Adapting to Pro Micro without "#include <functional>"

I'm trying to adapt CRSFJoystick, and so also this library, to run on a SparkFun Pro Micro. The error I am running into is:

CrsfSerial/CrsfSerial.h:4:10: fatal error: functional: No such file or directory

This means that I can't use the std::function syntax to declare the event handlers.

My software experience is primarily Python so I am struggling with the deep magic here, would you be able to help me get this compiled for my platform please? I don't really know what I am doing but I think I have worked out that the SparkFun board for the Arduino IDE doesn't have a new enough C compiler. Do you think that using platformio might be able to make a difference?

Use STM32 as a receiver.

Hello! I have a reverse question. I have a flight controller and I need to transmit control signals to it from STM32 via UART. I realized that CRSF is good for this task. Please tell me, is it possible to emulate a receiver (for example, ExpressLRS) on STM32? Thank you!

Servo.h and Servo.cpp

Hello Bryan,

I notice the code for a Pico will not compile. There are errors for undefined variables, some of which require Servo.h and Servo.cpp files, but these files are not included in the library.

Are the Servo.h and Servo.cpp files standard files that can be pulled from another source? Do you know where you were planning to get the Servo.h and Servo.cpp files?

Should we design a custom PCB for this?

The bluepill is rather large and certainly not tailored to this application.

Would you like to work on a custom PCB? I could sketch something in KiCad, maybe with a smaller MCU, and make it better and more compact. I already like the fact that there's an analog input for the battery voltage, and we could pave the way for current measurements, too.

i want use for teensy 4.0

what do i need to change so i can use it on board teensy 4.0

Can this code used to convert pwm to the elrs TX

I was thinking can I use STM32 to convert pwm siginal to to ELRS diy TX.

Add SBUS output feature

Hello,
Is it possible to add one SBUS output?
Thanks

Use CrsfSerial with Arduino RP2040 Connect

Hi,

I'm building a robot using an Arduino RP2040 Connect. I want to control the robot using ELRS. I found this project which uses an Pi Pico CRSFJoystick that uses your library so it seems like your library should work with the RP2040 chip. I've uploaded the basic_crsf example to the board, it compiles just fine but I'm not seeing a signal. I'm not sure whether I'm using the right RX and TX pins on the board.

I see in the code you can select Serial1 or Serial2 but I'm not sure what they refer to. The Arduino pinout only lists one RX and TX so I tried that first but I also see that on the Pi Pico pinout there are other pins for other serial ports so I tried connecting to the equivalents of those pins.

Is there something else that I'm missing?

Thanks

Porting serial passthrough to CRSFJoystick - Stuck on timeout

I figured since CRSFJoystick uses the crsfSerial library this should be possble. Here's my attempt at getting this to work on an rp2040 based CRSFJoystick:

https://gist.github.com/countofkrakow/1e26d9006461901a3011a02b911ca8a3

I try flashing an rx with the ELRS configurator and it seems to handle the handshake for going into bootloader mode but then I get a timeout after that. I looked into how serialpasssthrough is done by betaflight and copied the logic into a function and tried that but the configurator just hangs indefinitely that way. This can be found commented out in the gist above in checkSerialInPassthrough.

Here is output from the configurator with my adapted arduino code.

`Building in release mode
PLATFORM : 'espressif8266'
BUILD ENV: 'HAPPYMODEL_EP_2400_RX_VIA_BETAFLIGHTPASSTHROUGH'
Retrieving maximum program size .pio\build\HappyModel_EP_2400_RX_via_BetaflightPassthrough\firmware.elf
Checking size .pio\build\HappyModel_EP_2400_RX_via_BetaflightPassthrough\firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM: [==== ] 43.2% (used 35388 bytes from 81920 bytes)
Flash: [==== ] 37.1% (used 379552 bytes from 1023984 bytes)
Configuring upload protocol...
AVAILABLE: custom, espota, esptool
CURRENT: upload_protocol = custom
Uploading .pio\build\HappyModel_EP_2400_RX_via_BetaflightPassthrough\firmware.bin
Uploading .pio\build\HappyModel_EP_2400_RX_via_BetaflightPassthrough\firmware.bin
======== PASSTHROUGH INIT ========
Trying to initialize COM6 @ 420000

Attempting to detect FC UART configuration...
** Serial RX config detected: 'serial 5 64 0 0 0 0'
Enabling serial passthrough...
CMD: 'serialpassthrough 5 420000'
======== PASSTHROUGH DONE ========
======== RESET TO BOOTLOADER ========

• Using full duplex (CRSF)
  Cannot detect RX target, blindly flashing!
  Uploading .pio\build\HappyModel_EP_2400_RX_via_BetaflightPassthrough\firmware.bin
  esptool.py v3.0
  Serial port COM6
  Connecting......................................_____

A fatal error occurred: Failed to connect to ESP8266: Timed out waiting for packet header
*** [upload] Error 2
========================= [FAILED] Took 20.10 seconds =========================

Environment Status Duration

---

HappyModel_EP_2400_RX_via_BetaflightPassthrough FAILED 00:00:20.101
==================== 1 failed, 0 succeeded in 00:00:20.101 ====================`

I looked around on the CRSFJoystick page and mikeneiderhauser thinks it's an issue with dynamic baud rate.

Any ideas?

Failsafe

失控故障时，CH5和CH6没输出自定义PWM值，其它通道输出了自定的WPM值，是什么原因？

In case of out-of-control fault, CH5 and CH6 do not output customized PWM values, while other channels output customized WPM values. What is the reason?

How to add support for flightMode?

Hello, I would like to add support for flight mode to the library, but I'm not quite sure how to do it. In the Arduino file, I added a function:

void sendFlightMode(uint8_t flightMode) { crsf.queuePacket(CRSF_SYNC_BYTE, CRSF_FRAMETYPE_FLIGHT_MODE, &flightMode, sizeof(flightMode)); }

I uncommented the line
// CRSF_FRAMETYPE_FLIGHT_MODE = 0x21, //no need to support?'

I don't know how to modify the other library files. Could someone help me?

PETER

My proto not running

Hello, thanks for this wonderful share !
I use this library https://github.com/stm32duino/BoardManagerFiles/raw/main/package_stmicroelectronics_index.json on a BluePill board.
I compile the sources under the Arduino IDE.
May be the libraries are bad for your system ?
For my test, i use a TBS TX/RX system.
So, my wiring is like that:
TARGET_BLUEPILL pinout
#define APIN_VBAT A0
#define USART_INPUT USART2 // UART2 RX=PA3 TX=PA2
#define OUTPUT_PIN_MAP PA_15, PB_3, PB_10, PB_11, PA_6, PA_7, PB_0, PB_1 // TIM2 CH1-4, TIM3CH1-4

When i shutdown my transmitter, the green led is off and when my transmitter is on , the green led is on.
But, i have no PWM signal on the channel 1.
We try to add to our OpenAVRc transmitter the CRSF protocol and we are not certain of our code.
Thanks for your help,

Pierre

Adding Failsafe Adjustment

Hello Bryan,

Is there an easy way for the user to adjust failsafe settings?

For example, could the ELRS team "simply" add the failsafe WebUI configurator to select non-PWM receivers?

Or, if that is not so simple, then could a LUA script be used to adjust Failsafe settings over UART from the receiver to the BluePill or RP2040?

Adding ESP32 S2 support target hw: lolin_S2_mini

@CapnBry
Thanks for that code.

I managed to get the CRSF link running on the wemos LolinS2_mini.
The only challenge was to feed the used serial port in numbers to CRSR.begin() function, as on the ESP32 S2 they are not fixed.
Seen a lot of beauty in the code ... CRSF serial telemetry, I learned a lot.
Now merging some ESP HW PWM code to it.

CRSF Feature Creep

Bryan,

Good job on the adapter. Nice clean code.

Betaflight/CrossBow seem to have feature creep with CRSF. Do you know whether CRSF_FRAMETYPE_RC_CHANNELS_PACKED and CRSF_FRAMETYPE_LINK_STATISTICS packet types will remain the baseline for ExpressLRS. Some of us write our own flight control code and tracking moving specs does not thrill me. Apologies for the cross post on ExpressLRS..

Thanks
Greg

Target for CJMCU1038 - Purple Pill

I have some of these Purple Pill boards lying around:
https://stm32-base.org/boards/STM32F103C8T6-Purple-Pill.html
My Idea was to use them for your project, as they are small and have a proto area which makes it easy to solder a 6x3 Pin Header for the Servos.

I tried to make a new Target for the board using the pins that are broken out on the board.

#elif defined(TARGET_CJMCU1038)
      #define DPIN_LED        PB_11
      #define LED_INVERTED    1
      #define APIN_VBAT       PB_0
      #define USART_INPUT     USART1  // UART1 RX=PA10 TX=PA9
      #define OUTPUT_PIN_MAP  PA_0, PA_1, PA_2, PA_3, PB_3, PB_2, PB_1, PA_4 
 #endif

I am able to compile and flash the code, it seems to connect to the receiver but i don't get the right servo outputs.
I enabled some printlines in your code and the serial console says:

ADC=0 0V
ADC=0 0V
6666
�␌␔␀␀␀␀␀␄␀␀␀␀��␌␔␀␀␀␀␀␄␀␀␀␀ADC=0 0V
ADC=0 0V
ADC=0 0V
ADC=0 0V
tentative conn
30dBm

And then it seems stuck.

On pins PA_0, PA_1, PA_2, PA_3 i can see a 50Hz servo signal with 1700ms. The other pins show nothing.
I guess its some problem due to the used timers for my pins that need to be changed. Maybe you can point me in the right direction.

Thanks a lot
Johannes

Any reason this will not work with raspberry pi pico

I am just asking because I have a few picos with me. Just want to make sure that Pico is powerful enough to do this.

CrsfSerialStream undefined

Hello Bryan,

I am attempting to compile the CRServoF project but I keep getting an error that states CrsfSerialStream is undefined. I have looked through the following files and have determined the error is accurate.

CrsfSerial.h, CrsfSerial.cpp, and Crsf-protocol.h

Can you tell me what is CrsfSerialStream and where is it intended to be defined?

Thank you,