How to send telemetry poll request from Handset to Flight controller

[Hamo-creator]

Hello,
could you please demonstarte the issue i titled in an example?
sending telemetry (e.g. Battery) from FC is continuously, but can i make the FC only send the telemetry when it receives a poll request?
Could you help with that?
on the Handset side i am using a custom one (Ranger Micro with a MCU) DIY.
Or will this Library work on the Handset side?
Thanks

[SaintSampo]

I don't see this as an issue but below is one way to do that. I asked Gemini to combine existing example code to make a file that sends a single telemetry packet whenever channel 6 is set to 2000. it wont send another packet until channel 6 is reset, and then set to 2000 again:

#include <AlfredoCRSF.h>
#include <HardwareSerial.h>

// CRSF Communication Pins
#define PIN_RX 7
#define PIN_TX 8

// Battery Sensing Constants (from example)
#define PIN_SNS_VIN 3
#define RESISTOR1 15000.0
#define RESISTOR2 2200.0
#define ADC_RES 8192.0
#define ADC_VLT 3.3

// Set up CRSF objects
HardwareSerial crsfSerial(1);
AlfredoCRSF crsf;

// State management for one-shot triggering
bool telemetryTriggered = false;
float cap = 0;

void setup()
{
  Serial.begin(115200);
  Serial.println("Telemetry Trigger Initialized");
  
  crsfSerial.begin(CRSF_BAUDRATE, SERIAL_8N1, PIN_RX, PIN_TX);
  if (!crsfSerial) {
    while (1) Serial.println("Invalid crsfSerial configuration");
  }

  crsf.begin(crsfSerial);
}

void loop()
{
  // Must call crsf.update() to process incoming RC data
  crsf.update();

  // Get current value of Channel 6
  int channel6Value = crsf.getChannel(6);

  // Trigger Logic
  if (channel6Value == 2000) {
    // Only send if we haven't already triggered for this specific event
    if (!telemetryTriggered) {
      Serial.println("Channel 6 hit 2000! Sending telemetry...");
      
      // Calculate battery data to send
      int snsVin = analogRead(PIN_SNS_VIN);
      float batteryVoltage = ((float)snsVin * ADC_VLT / ADC_RES) * ((RESISTOR1 + RESISTOR2) / RESISTOR2);
      
      // Send the packet
      sendRxBattery(batteryVoltage, 1.2, cap += 10, 50);
      
      // Set flag so we don't send again until channel is reset
      telemetryTriggered = true;
    }
  } 
  else {
    // If the channel is moved away from 2000, reset the trigger
    telemetryTriggered = false;
  }

  delay(10);
}

/**
 * Sends a battery telemetry packet to the radio
 */
static void sendRxBattery(float voltage, float current, float capacity, float remaining)
{
  crsf_sensor_battery_t crsfBatt = { 0 };

  // Values are MSB first (BigEndian)
  crsfBatt.voltage = htobe16((uint16_t)(voltage * 10.0));   // Volts
  crsfBatt.current = htobe16((uint16_t)(current * 10.0));   // Amps
  crsfBatt.capacity = htobe16((uint16_t)(capacity)) << 8;   // mAh
  crsfBatt.remaining = (uint8_t)(remaining);                // Percent
  
  crsf.queuePacket(CRSF_SYNC_BYTE, CRSF_FRAMETYPE_BATTERY_SENSOR, &crsfBatt, sizeof(crsfBatt));
}

[Hamo-creator]

Hello and thanks for your reply,
i am now doing the same (almost) in the FC side, so i am sending the telemetry to the Handset continuously.
On the Handset side i do not recieve the telemetry (strange).
I must say this that i am using a STM32F4xx MCU and not arduino and working on STM32Cube IDE.
But with some modification your library works on the FC side.
If you want i can share my git with you to take a look on my work so fare.

[SaintSampo]

what Handset are you using? is it with edgeTX? have you run "Discover new sensors"?

[Hamo-creator]

A DIY (self made) handset.
DIY Software.