#ELRS 433 MHz

112 messages · Page 1 of 1 (latest)

gusty python
#

Can you tell me how to solder an ELRS 433, as well as how to flash it, and if possible, add an OLED display?

fiery spoke
#

This is a very vague question - what hardware do you have?

gusty python
fiery spoke
gusty python
fiery spoke
gusty python
#

I need a frequency below 700 MHz

gusty python
fiery spoke
gusty python
fiery spoke
#

Which firmware you upload will depend on how you wire up the SPI pins

fiery spoke
gusty python
willow moss
#

the module you described will need another microcontroller to handle the translation between the data received/sent to functional input/output as well as the code for the OLED. what's the full scope of your project?

fiery spoke
gusty python
fiery spoke
#

So, let's be very frank:

"I want to build a car. I have these tires, and an engine. I want to add a gauge cluster too."

Well, what you have are motorcycle tires, and your engine is four pistons and a crankshaft. We need you to meet us halfway. Which ESP32? Are you gonna solder the EByte modules to the ESP32? Is this the RX or TX side you're doing first?

gusty python
fiery spoke
gusty python
#

For the receiving side, I want to use the E32-400M20S and the ESP32 SuperMini. or DIY board

gusty python
#

Sorry that I'm so slow, but for me as a web developer, this is a new world that I'm very interested in.

willow moss
#

they wouldn't be pin declarations but other variables set for the rest of the code you'll be uploading

#

you'll be hooking up the transmitter module to the pins specified in the configuration file then building the firmware with the ELRS configurator.

earnest coral
willow moss
gusty python
earnest coral
willow moss
#

besides the hardware difference to modulate 433MHz and 900MHz, is there any difference in how the controller talks to the radio module? I would think a 900mhz build should work for 433 if there isn't any commands that specify the frequency used apart from values on a table

earnest coral
#

No, everything else is the same

willow moss
#

Alright, so for them flashing the TTGO 900mhz build from the ELRSConfigurator should work well with an ESP32 and IIC 128x64 display

earnest coral
#

If the pin assignments are the same and they use the correct regulatory domain

willow moss
#

what board are you using for the RX? @gusty python

willow moss
#

so i got the firmware for the esp32 900mhz flashed to a ttgo v1 as a receiver and a esp module with that lora chip and a IIC display as a transmitter. both are connected over seial to my computer but I'm getting just nonsense at 420000 baud, is there something else i should be setting it to?

fiery spoke
willow moss
#

a boot sequence log, I have the ttgo plugged into my computer through a ftdi chip and I'm getting a "brownout log" at that baud

earnest coral
#

How are you powering it? Just via FTDI?

willow moss
#

for now yhea, the brownout warning is obviously no good but it's an indication of readable output

earnest coral
#

Use a different power supply

#

Make sure you keep a ground connected to the FTDI though

willow moss
#

👍 trying to figure out a way to see if I'm sending/receiving properly over the link

#

ah, Alessandro made some CRSF package generation scripts for arduinos, looks like I'm going to have to get 2 more microcontrollers to get any data dyingorangutan

earnest coral
#

Why? What are you using now?

willow moss
#

endgame is using 915Mhz lora modules to make a backpack for my radiomaster boxer to drive a RC tank

#

I just have the receiver/transmitter wired up to 915Mhz modules and serial to my computer on both of them to see if it's kosher

#

I don't want to threadjack so I've been keeping it to flashing and using low frequency lora modules as per the original post

gusty python
gusty python
gusty python
willow moss
#

normally if it's not software defined radio the range of a tranceiver is limited by the RC circutry, I think even if the sx1276 is designed to handle that range it's with other passive components that dictate what the actual range is

earnest coral
gusty python
#

Understood

earnest coral
#

Why the requirement for <700MHz?

gusty python
#

As for the firmware for the 433 module, should I use TTGO 900MHz?

willow moss
#

that would probably be the closest thing to it, I've been trying out some things on my own along those lines but nothing came ut of it yet

earnest coral
#

Just use the unified target matching your hardware and then edit the pin definitions in hardware.html

gusty python
#

I installed equipment operating at 900 MHz on my airplane, and it jams the transmitters. 2.4 GHz is too high a frequency, and I need to fly close to the ground. I even have a 15-meter mast.

#

But this equipment emits a lot of noise on other frequencies, so I need a transmitter on 433 MHz

willow moss
#

any way to sheild the equpment?

gusty python
#

There are omnidirectional antennas installed, and the main unit is in a ventilated case, otherwise it overheats during flight.

willow moss
#

I'm building for the unified firmware for esp32 right now like V22 suggested, looks like through the hardware page i can just set my pins so fingers crossed I won't have to do any more soldering.

earnest coral
fiery spoke
gusty python
#

Wavelength: The lower the frequency, the longer the wavelength. Longer radio waves can better circumvent or penetrate obstacles than shorter waves.

Absorption: All materials absorb radio waves to some degree. At higher frequencies, such as 900 MHz, materials like brick or concrete may absorb radio energy more than at lower frequencies, such as 433 MHz.

Scattering: At higher frequencies, radio waves are more prone to scattering on irregularities and small objects. At low frequencies, waves are less sensitive to such small obstructions.

Refraction: At low frequencies, radio waves can bend around obstacles or penetrate them better due to the phenomenon of refraction.

fiery spoke
#

... You're talking to a chat full of very experienced people.

#

By "too high for what", what I mean is "what analysis have you done that says it wouldn't work for your use case?"

gusty python
fiery spoke
#

In other words, where's your free-space path loss calculations? Your fresnel calculations? Your clutter models?

#

2.4GHz will perform better lower to the ground than 433MHz due to the fresnel zone's area being negatively correlated with frequency.

gusty python
#

I didn't do the calculations, but flying on 2.4, the connection lasted up to 34 km, although with TBS I achieved a greater distance.

fiery spoke
#

Okay... 2.4GHz ELRS? What settings? What antennas?

gusty python
#

1W yagi 22dBi

willow moss
#

good news, build upload and settings were sucessful on my esp32 / 433MHz build

#

it's getting late so I'm going to wait till tomorrow to upload and connect the RX version to my radiomaster, then some short tests outputting PWM should say if everything is 100%

gusty python
willow moss
#

I wouldn't jump the gun on wiring just yet, I followed the guide for the esp8285 by mistake to the ESP32 and there might be some variance for the pins used

#

that being said the web page of the receiver lets you inputs LOTS of variables

#

and don't use the ttgo, the "unified" build seems to be a lot more versatile

fiery spoke
# gusty python 1W yagi 22dBi

... Update rate? LNA RX?

A 22dBi antenna would have a very narrow beamwidth. How did you assure your RX was within its beamwidth?

#

Your range should be nearly 1000km with a 22dBi antenna and 1W TX power... So I suspect your antenna did more harm than good.

#

I say this as one of the very few people using 433MHz ELRS, with my own custom board designs to do Gemini 433MHz.

#

2.4GHz is the right solution for 99.999% of cases. I'm worried you're jumping to conclusions and adding significant complexity where it's not needed.

gusty python
#

Alright, I'll add an antenna tracker to the 2.4 GHz setup, but I also want to make a transmitter and receiver on 433 MHz.

fiery spoke
willow moss
#

that looks amazing @fiery spoke

#

I'm going to resolder my receiver today, do you recommend me going with the hardware SPI0 pins or with the pins in the gemini .json file?

willow moss
#

@gusty python I got it all workin! lmk where you're at with yours and i can tell you where to go

gusty python
ripe herald
#

Hi. Anyone tried changing carrier frequency by chnging RegFr values?

#

Let say I have 433MHz lora and want to use 900MHz target. If 900 carrier is too high 750MHz should work with HF filter without hardware modifications... Theoreticaly

willow moss
#

the 900 target is the same for all of the sub ghz, you can just change the regulatory domain in the settings

#

From the html page of the "generic_900" target

Screenshot_20231020-063835.png
#

The soldering is using the hardwareSPI ports for 50% of the connections, the reset and di0 I put on pins that were close to them and available for basic GPIO functions.

#

I'm going to be using that one in the pic for something with lots of PWMs, I ordered a 1W 433mhz transceiver for the external module of my controller which will be paired with a WeMos D1 mini because all of the connections plus a sbus can be achieved with it's limited amount of pins. Plus they're cheaper $$

ripe herald
#

Not sure if it'll work. But I'll try this out...

image.png
willow moss
#

550mhz might be too big of a mismatch for the RC hardware. Check on the datasheet to see how much power it'll actually put out on that frequency

ripe herald
fiery spoke
willow moss
#

that's a issue as well. @fiery spoke I see you've made most of the firmware for VRx backpacks, I'm struggling a bit to adapt it for a headtracker. Do you have time to help?

fiery spoke
willow moss
#

that would be a great help, I'm going to try to skip the SBUS part and just do reads from a MPU6050 and then.... smoothing algorithms 🙃

#

Hopefully an esp01 has the firepower for something like this, the disable/recentering with a controller aux makes it feasible to implement on something that only has 2 usable GPIOs

IMG_20231020_084719_860.jpg
fiery spoke
willow moss
#

lol, they're so cheap and I've been using them for the most menial things