LoRa pager on M5StickC + CardKB

[skuhu]

Hi everyone,

i'm planning to build a small pager device, base on the M5StickC.
I would like to have a keyboard so i thinked of the CardKB.

Last but not least i want to use a LoRa Ai Thinker RA-02 Module juste as in the M5Stack LoRa Module.
The original module uses GPIO : 5/26/36 as CS/RST/IRQ.

Thats good as the M5StickC has GPIO 0/26/36 in front.
And i suppose that re-mapping GPIO 5 on GPIO 0 should be feasible.

Problem is that the RA-02 also needs MOSI/MISO/SCK that are wired to GPIO 23/19/18
and the M5Stick doesnt have more exposed GPIO.

GPIO 18/23 are used by the LCD.

As i'm new to electronics, i understand that MISO/MOSI are terms related to the SPI interface.

Is there a way to connect the needed GPIO ?

Via the Grove connector ?
As i understand the grove connector provides an I2C interface.

It seems possible to use SPI over I2C with this type of modules :
https://fr.aliexpress.com/item/32858332883.html?spm=a2g0o.productlist.0.0.2c9d2615RyHRrO&algo_pvid=08866c52-58d9-4ab4-af44-1d4dd6947ce1&algo_expid=08866c52-58d9-4ab4-af44-1d4dd6947ce1-3&btsid=082e32bc-8da8-4dec-bc60-5fa244c0ce4b&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_52
https://fr.aliexpress.com/item/976713163.html?spm=a2g0o.productlist.0.0.2c9d2615RyHRrO&algo_pvid=08866c52-58d9-4ab4-af44-1d4dd6947ce1&algo_expid=08866c52-58d9-4ab4-af44-1d4dd6947ce1-4&btsid=082e32bc-8da8-4dec-bc60-5fa244c0ce4b&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_52

Or using these (but a bit expensive, rather have a M5Stack instead of the stick) :
https://www.gotronic.fr/art-module-grove-lora-113060007-25947.htm

Thanks,
Philippe

[grisu]

Hello Phillipe,
It would be easier to use a Module with embedded LORA stack, which you can control with Modem AT instructions:
https://www.instructables.com/id/Get-Started-With-UM402-LoRa-433MHz-UART-Using-Ardu/

[dda]

MOSI/MISO is the SPI equivalent of Tx/Rx for UART (except the lines are not crossed: MOSI connects to MOSI, and MISO to MISO). The other difference is that's it's a bus, like I2C, with one master and one or more slaves. So you can connect a screen and a LoRa chip, for instance. However, you need a separate SS (Slave Select) line per device. You're going to have difficulties finding enough pins for this. As suggested, it'd be much better to use a managed chip (MCU + LoRa chip).

I've tried a few things but it's too cumbersome. I switched back to M5Stack for this.