M5Paper & Lora

stantheman

Hi,

A question from a beginner... does a M5Paper could be connected to module like Lora Module :
https://shop.m5stack.com/products/lora-module-868mhz?_pos=2&_sid=950ff4cfa&_ss=r

Regards

Stan

felmue

Hello @stantheman

I don't think it is possible. The LoRa module uses SPI to communicate. M5Paper internally uses SPI already, but those GPIOs (14, 12 and 13) are not accessible.

According to ESP32 documentation there is a second SPI connection available, but the respective GPIOs (18, 19 and 23) are not all available / accessible on M5Paper.

I am sorry, but I think you are out of luck.

Thanks
Felix

loboris

@felmue
You can configure SPI to work with (almost) any GPIO on ESP32.

felmue

Hello @loboris

I stand corrected. You are right. Thank you for pointing that out.

The GPIOs of the second SPI connection I've mentioned above (18, 19 and 23) are only relevant if one needs SPI bus speeds above 40 MHz apparently. If the SPI bus speed is 40 MHz (or below) almost any GPIO can be used for SPI as you pointed out.

Thanks
Felix

stantheman

Thanks Felmue, thanks Loboris,

What I understand is that I need to check first that SPI bus speeds above 40 MHz will not be used in my whole project. My project is to build a numerical swich panel for my sailboat (about 20 instruments to manage) , and also manage power consumption/production from solar panels, engine etc...

Regards

Stanislas

loboris

@stantheman
You don't need to check anything, just configure spi for lower speed.
There is not much sense in using fast spi clock with LoRa module, 1 MHz is probably enough.

BTW, there are some LoRa modules which operates over serial port (UART) which are quite easy to use (like this one or this one).

LoRa-E5 (STM32WLE5JC) Module is also very interesting and supports LoRaWAN too.