Clarification Needed "Rocket Model"

Other Hardware General Electronics
41

Thank you! I will post in the networking category to discuss transceiver selection and data, as I have now realized the limitations of the Xbee Pro.

Good news though, prof. gave approval to choose a stronger microcontroller to support adding a video camera. so now the pending points are:
Camera selection
Microcontroller selection
Transceiver chip selection

while the other peripherals are confirmed:
IMU
BMP280
Thermocouple amplifier
Resistor 50 Ohm and the pressure transducers
And I think I have a clear understanding of the power demands, communication protocol, and data requirements for these peripherals.

To proceed I need to still do the following:
Check which camera to use and adjust the data requirements accordingly.
Select a transceiver that can handle the new total data transmission (Includ. the camera) .
and finally choose a microcontroller capable of managing all operations.

I'm thinking maybe a VGA camera (640 * 480) or 2Mp (1600*1200).

will ask on the post group maybe we continue there.

42

@rsmls Hello! I hope you had a nice summer!
We've purchased most of the items for the project and we will start testing in the coming weeks. I'm in need of some hands-on experience, we got the 50 Ohm resistor. the following:

However I'm trying to find a secure way to connect it with the Pressure transducer and the nano board, since it will be in a moving model rocket with lots of vibration and forces on the parts. Can you advise of a method to connect this resistor in a secure way?

Thank you!

43

30W is a beast. As a 4-20mA sensing resistor, your 50 ohm resistor only needs to handle P=I^2xR=0.02^2x50=0.020 watts. A tiny SMD or 1/8w resistor might be easier to mount.

44

Thank you for your reply!
I will check selection a new resistor, and how would you recommend connecting it? I'm worrying that soldering is not a good idea given all the vibration, can you recommend a better way?

45

Soldering seems perfectly fine. How do you expect it would fail?

46

I'm worried with the strong vibrations and shaking it could break the soldering. or highly unlikely?

47

@rsmls Hello! Following our previous discussion, so for the camera, we have decided to proceed with a separate system, and use the microcontroller for the sensors only. We will use a commercial Walksnail Avatar like the ones used for drones, using the VTX on the rocket, and the VRX connected to the ground stating via and Hdmi, that seemed like the easiest way to do it.

I wanted to ask you do you think that it is preferred to add capacitor to clear the signal? and if so should I use it with the transmitter and the sensors or can you advise a bit please?
Thank you!

48

Use leaded solder! That has been used in ALL aircraft and rockets, etc. for almost 100 years without failures. Only when lead-free solder began to be used did problems occur.

49

Ok thank you! I’ll check it out.

50

Can anyone suggest if there is a necessity to add capacitor and resistors to my schematic? For example while connecting my sensors to my microcontroller or between the transmitter and controller?

51

The only schematic is the module connections shown in your first post. Do the modules have capacitors and resistors? Most likely.

52

Yes the modules have, but I'm wondering if we should install external as well to better clean the signal from noise between the transmitters and the controller.

53

Hello everyone, I'm working on the code for transmission using the Gamma62T as transmitter.

Can anyone give me some guidance where I can find coding material to to setup the communication between the two transceiver?

54

There is no code involved. How to pair the transmitter and receiver and select communication modes is explained in the datasheet.

55

Thank you for the reply. so I followed the data sheet and setup the gamma in transceiver mode. now I have one of the transceiver connected to a raspberry pi 4 (will use Python) for the ground station. and the second to an arduino nano for the rocket model. however when I want to test the communication between the rocket and the ground station I'm having issues.
I connected with the GPIO pins but I'm a bit stuck on the transmission and reception code. as a first step I'm trying to send a simple message just to test the connection.

56

Sorry I don't know anything the RPi 4 and python but for the nano you just need to read the pins you have the Gamma outputs. If the transmitter sets one low the corresponding receiver pin should go low.

57

Hello @jim-p , I decided to remove the RPi4 and instead used an arduino Uno, I've used the following codes, and Instead of both working as transceiver, I'm using the GAMMA62T connected to the arduino rp2040 as a transmitter, and the one connected to the arduino uno as a receiver.
Following is the code of the transmitter with rp2040:

void setup() {
    // Initialize USB serial communication for debugging
    Serial.begin(19200);
    while (!Serial) {
        ; // Wait for Serial to connect
    }
    Serial.println("Message transmission initiated");

    // Initialize UART communication
    Serial1.begin(19200);
    Serial.println("Serial1 initiated");
}

void loop() {
    // Send a test message over UART
    String message = "Hello from Arduino via UART";
    Serial1.println(message);
    Serial.print("Transmitting: ");
    Serial.println(message);

    delay(1000); // Wait for 1 second
}

and the following code for the receiver on the UNO

#include <SoftwareSerial.h>

#define RX_PIN 2
#define TX_PIN 3

SoftwareSerial Serial1(RX_PIN, TX_PIN);

void setup() {
    Serial1.begin(19200);   // For debugging
    Serial.begin(19200); // For Gamma62T communication
    Serial.println("Receiver Ready");
}

void loop() {
  if (Serial1.available() > 0) {
    String receivedMessage = Serial1.readStringUntil('\n');
    Serial.println("Received: " + receivedMessage);
    }
}

Very simple codes.
The TX on the UNO is only name for the SoftwareSerial to work, put nth is connected to the pin.

I'm getting unreadable characters in the form of squares.

58

I don't understand what you are doing, the GAMMA62T can't transmit and receive serial.

59

I think I agree with you, even though before they had it written on their website page of the GAMMA62T that the user interface is TTL / UART. now it only shows TTL, and I don't understand why the data sheets mention serial communication:

image
image947×745 97.5 KB

Can you advise if I can use this for my application? to transmit data from the sensors on the rocket model ? and what would be the approach? GPIO communication only? is it doable ?

60

This transceiver module is designed to transmit the state of a number of GPIO inputs, as in whether or not the GPIO input represents a HIGH or a LOW input, and the example is given as sensing the state of switches connected to this inputs. The information is sent in 10-byte packets to the corresponding receiver module and 2 bytes of that packet are actually the data representing the switch states. There is a serial connection on the receiver section that is used to get that packet into an attached microcontroller.

I don't think it would work too well as a sensor data communication device as it would only transmit 2 bytes at a time and you would have to set up those 2 bytes by emulating switches on the GPIO inputs. You could load that data via a shift register driven by a controller that got all the data from your sensors but it seems like a strange way to do it to me.