SPI.h doesn't work with Nano BLE 33

[marcoumlaut]

I've used an Arduino Nano with SPI.h to make a SPI Slave. Now I have the Nano 33 BLE and want to use the same code, but there are Errors when I build the file. Does anyone have an idea what's the issue?

The Code:

#include <SPI.h>

volatile byte c;
volatile byte command = 0;

void setup (void)
  {
  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  pinMode(MOSI, INPUT);

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPI.attachInterrupt();
  
  Serial.begin(115200);
 }  // end of setup

// SPI interrupt routine
ISR (SPI_STC_vect)
  {
  c = SPDR;
  Serial.println(SPDR);

  //SPDR = 8;

  }  // end of interrupt service routine (ISR) SPI_STC_vect

void loop (void)
  {
  if (digitalRead (SS) == HIGH)
    command = 0;
  
  }  // end of loop

The Error:

src\main.cpp: In function 'void setup()':
src\main.cpp:15:3: error: 'SPCR' was not declared in this scope
   SPCR |= _BV(SPE);
   ^~~~
src\main.cpp:15:3: note: suggested alternative: 'SPI'
   SPCR |= _BV(SPE);
   ^~~~
   SPI
src\main.cpp:15:15: error: 'SPE' was not declared in this scope
   SPCR |= _BV(SPE);
               ^~~
src\main.cpp:15:15: note: suggested alternative: 'SPI'
   SPCR |= _BV(SPE);
               ^~~
               SPI
src\main.cpp:15:11: error: '_BV' was not declared in this scope
   SPCR |= _BV(SPE);
           ^~~
src\main.cpp: At global scope:
src\main.cpp:24:5: error: expected constructor, destructor, or type conversion before '(' token
 ISR (SPI_STC_vect)
     ^
*** [.pio\build\nano33ble\src\main.cpp.o] Error 1

[facchinm]

Hi @marcoumlaut ,
all arduino libraries are portable as soon as you don't use any architecture specific code in your sketch.
In this case, SPDR and friends are registers that only exists in AVR microcontrollers.
If you need to implement an SPI slave there isn't a wrapper yet for Nano33BLE but these APIs https://os.mbed.com/docs/mbed-os/v6.6/apis/spislave.html can be used

[marcoumlaut]

Hi @facchinm ,
thank you for the answer.
But when I compile it I get the error description:

src\main.cpp:4:1: error: 'SPISlave' does not name a type; did you mean 'SPIName'?
SPISlave device(D12, D11, D13, D10); // mosi, miso, sclk, ssel
^~~~~~~~
SPIName
src\main.cpp: In function 'int main()':
src\main.cpp:8:5: error: 'device' was not declared in this scope
device.reply(0x00); // Prime SPI with first reply
^~~~~~
src\main.cpp:8:5: note: suggested alternative: 'dev_t'
device.reply(0x00); // Prime SPI with first reply
^~~~~~
dev_t
*** [.pio\build\nano33ble\src\main.cpp.o] Error 1

Can you help me with that, I'm new to SPI? Do I need more libraries?

[marcoumlaut]

I've found out there are inactive regions in the SPISlave.h library. Why is the whole code inactive there?

[manchoz]

@marcoumlaut because SPISlave is not supported on nRF52840 on MbedOS.