Nano 3
nokia 5110 (SPI)
project: Self-powered weather sensor station, talk to house via NRF2401s.
Experts,
My weather sensor station is working (sensors), and what is left is communication to house and self-powering. Networking seems a bit tougher, so I'm tackling that first. I have no problems with SPI and a single device (using 5100 now, in this case), but I want to add an NRF2401.
A few questions have arisen:
-Are the pins on the ICSP header the same as those default for an arduino board (see below)?
-Can I just use D4 (below) for the NRF (with other 3 same as the LCD)?
-Is the tmrh20 R24 lib enough for this? I mean, does the uC handle comms automatically?
Here is my current working schematic:
Note: I couldn't find a better BME280 component that had better pinout labels
"...on SPI...
On the Arduino Mega, the pins are 50 (MISO), 51 (MOSI), 52 (SCK), and 53 (SS)."
The MOSI MISO and SCK pins for SPI are used by every SPI device. The specific device you want to talk to is determined by the SlaveSelect pin (CSN on the nRF24). Any Arduino pin can be used for SS but you must use a different pin on the Arduino for each slave. Note that on an Uno pin 10 is usually used for SS for one SPI slave but it does not have to be. However it must be in OUTPUT mode to ensure that the Uno acts as SPI master.
The ICSP header pins are directly connected to the equivalent regular pins and you can use either - or both if it is convenient for a second SPI device.
This Simple nRF24L01+ Tutorial may help you get started. It uses the TMRh20 library. Make sure to get the wireless comms working on its own before adding in the code for your sensor.
...R
Robin2,
Thank you very much for writing. I should refine this a tad (equal to 2 smidgens)...
Which unit does the selecting? I've read that only one can be sending at a time, or at least selected. Makes sense with them all on the same 3 pins, but do I need to have my code instruct one to go hi, and the other low, or does the master simply negotiate first come, first served?
There are tons of examples and explanations of a single SPI device, but multiples are scarce. It may seem silly to get all this straight up front, but I've taken stock of my inventory, and I can't afford to blow modules/components experimenting [any more]. 
Robin2:
[...]
The specific device you want to talk to is determined by the SlaveSelect pin (CSN on the nRF24).
Thanks again!

holesflow:
Which unit does the selecting?
The master - which is almost certainly your Arduino. Your program needs to activate the appropriate SS line and then talk to the selected device.
...R
@Robin2,
Stupid me! I replied before I scrolled down that thread a bit to here (Simple nRF24L01+ 2.4GHz transceiver demo - #18 by Robin2 - Exhibition / Gallery - Arduino Forum), where multi-slave is discussed.
Please excuse my haste!
Thanks!
