LoRa SX1276 level converter setup

Hi, I want your guys advice to ensure I have all of the theory behind the wiring understood before I accidentally put 5V through the SX1276 which runs at 3.3V.

I will be using a Arduino Nano with a SX1276 LoRa transceiver module, which uses SPI. https://www.ebay.com.au/itm/282921878129 https://www.semtech.com/uploads/documents/DS_SX1276-7-8-9_W_APP_V5.pdf

Im planning on powering it using the Nano's 3.3V output and running the logic through a 74LVC245 level converter, which is unidirectional. (available at my local store). http://www.ti.com/lit/ds/symlink/sn74lvc245a.pdf

From what I understand I only need to run logic through the converter when going from the Nano to the SX1276? So I only need to have MOSI, SS, SCK and Reset going through the level converter as MISO DIO0, DIO1 and GND direction is going to the Nano? Will going from a 3.3V logic to the Nano's 5V logic have any issues?

Is all the above correct or should it be refined/ changed?

Thanks for your time.

What is the current output capability of the Nanos 3.3V output ?

How much current does the SX1276 need at 3.3V ?

I see what you are saying. Max output is 50mA from the nano and the lora emitter current is 120mA. So I will have to power it from an external source by the looks. What about my other assumptions?

Tocs: What about my other assumptions?

Well, the datasheet for the 328P will tell you the minimum voltage the 328P needs for a logic high on its inputs and the SX1276 will tell you the minimum voltage it will produce for a logic high on an ouput.

You would be running right on the limits (without logic level converter on the SX1276 outputs) so it will probably work, most of the time.

Lots of interesting stuff in datasheets, always worth a read.

I prefer to pair my LoRa devices with an 8 MHz 3.3V Pro Mini. No worries about voltage levels (but make sure you have a 3.3V FTDI as well or you may still fry the LoRa, and that it has a big enough 3.3V regulator!).

I will need to have a read through the data sheets to ensure I achieve all the min and max voltages.

For this project I'm also using a small Oled screen, a Bmp280 and a couple of servo connections that run at 5V. That is why I ended up picking the Nano over the mini.

I'm trying to keep things as small as possible aĺso as I want to put this thing in a bottle rocket to be able to record the altitude and also have ways of deploying a parachute. The reason for the LoRa is so I can control it and received data from the ground if needed.

Any more advice for me is always welcome. Thanks.

Tocs: Any more advice for me is always welcome.

Using a Nano for this seems quite peverse.

Ok I think I'll go a mini or other 3.3v logic board. The other components seems to also be able to run at 3.3v with the exception of the servo, which I'll just power from external.

My base station however I will be using a mega with a touch screen (I already have them). I will read up on the data sheets and hopefully all goes to plan.

Thanks for your advice.

The servos should be happy to be controlled at 3.3V. Just supply them with the higher voltage as power input, you have to wire that separate from the board anyway.

The servos will require their own power supply, 5-6V at typically 2 Amperes.