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I am currently having an ADC(MCP3008) connected to a rpi3, using the following wiring map, in order to read data from analog sensors.

MCP3008 -> RPI3 
VDD     -> 3.3V  
VREF    -> 3.3V  
AGND    -> GND  
CLK     -> #18  
DOUT    -> #23  
DIN     -> #24  
CS      -> #25  
DGND    -> GND  

Now what I am trying to do, is to also connect a LoRa RFM95W on the same rpi3, in order to transmit these data to a LoRa Gateway. The wiring for the LoRa node transmitter is the following.

RFM95W   -> RPI3  
3.3V     -> #1
GND      -> #6
DI00     -> #7
RST      -> #11
NSS      -> #22
MOSI     -> #19
MISO     -> #21
SCK      -> #23

So the two wiring maps seem to have nothing in common except from SCK on RPI pin #23. (And the power which is not a problem).

How should I wire the ADC and the transmitter on pin #23, should I follow that Daisy-chained SPI bus connection or should I plug both of them directly on pin #23?

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You should use Typical SPI bus: master and three independent slaves. In this topology you are differentiating the two peripherals with the CS (chip select) line. Not Daisy-chained SPI bus connection.

For a start I would connect the devices to the RPi3 with the pin #23 connected to both, probably it will not work. The correct solution is a the master and slaves topology.

MCP3008 -> RPI3

VDD -> 3.3V

VREF -> 3.3V

AGND -> GND

CLK -> #18

DOUT -> #23

DIN -> #24

CS -> #25

DGND -> GND

RFM95W -> RPI3

3.3V -> #1

GND -> #6

DI00 -> #7

RST -> #11

NSS -> #22

MOSI -> #24

MISO -> #23

SCK -> #18

  • on the rfm95w you say SCK #1, this is probably a typo ? – Christos K. Jan 6 at 21:01

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