<p>It turns out ELRS requires way higher communication protocol rates. So that's why they use SPI at multiple MGhz rates.</p>
<p>What's more, those UART modules are not really UART natively. I've dissambled one and it turns out the main radio chip they're working on is still the same and is still controlled over SPI. But it's using one extra MCU (let's say STM8) to handle a lot of communication. So that middle layer will add even more delay to the communication.</p>

CC BY-SA 4.0
2023-12-08T21:21:58.603Z
2023-12-08T21:21:58.603Z
Secret-guy
<p>I've seen official ELRS guides for building DIY RX/TX modules. Many of them offer to use SX12xx modules with the SPI pinout. However, I've seen the same modules but with UART control only.
Any reason why ELRS does not support those?</p>

<electronics><radio-frequency>
Why does ELRS use only radio modules with SPI control and UART?
Secret-guy
# Why does ELRS use only radio modules with SPI control and UART?

(Asked by: username_0 on 2023-12-08)

I've seen official ELRS guides for building DIY RX/TX modules. Many of them offer to use SX12xx modules with the SPI pinout. However, I've seen the same modules but with UART control only.
Any reason why ELRS does not support those?

**Tags:** electronics, radio-frequency


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## 1 answers

### Answer by username_0 on 2023-12-08. Score: 1 | Accepted answer

It turns out ELRS requires way higher communication protocol rates. So that's why they use SPI at multiple MGhz rates.

What's more, those UART modules are not really UART natively. I've dissambled one and it turns out the main radio chip they're working on is still the same and is still controlled over SPI. But it's using one extra MCU (let's say STM8) to handle a lot of communication. So that middle layer will add even more delay to the communication.


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