32 bit data transfer?

[mateusz-kusmierz]

I'm using teensy 4.1

Is it possible to send 32 bit data as shown here?
0b00000000000000000000000000000111 is beeing sent out (DATA-blue, CS-red, CLK-yellow)

Because currently I can only manage to get this using this SPI.h library:

and this code:

 SPI1.beginTransaction(settings);
SPI1.transfer(0x00);
SPI1.transfer(0x00);
SPI1.transfer(0xFF);
SPI1.transfer(0x00);
SPI1.endTransaction();

Clock distortion after 8 bits, and CS high, is issue for me.
As far as I know teensy 4.1 processor should be able to do 32bit SPI data transfers.

Regards Mateusz

[mateusz-kusmierz]

I have modified SPI.h library and added transfer32 function starting in line 1258 after transfer16 function is finished.

uint32_t transfer32(uint32_t data) {
		uint32_t tcr = port().TCR;
		port().TCR = (tcr & 0xfffff000) | LPSPI_TCR_FRAMESZ(31);  // turn on 16 bit mode 
		port().TDR = data;		// output 16 bit data.
		while ((port().RSR & LPSPI_RSR_RXEMPTY)) ;	// wait while the RSR fifo is empty...
		port().TCR = tcr;	// restore back
		return port().RDR;
	}

This works, however I did not test it for receiving 32 bits of stream. Only sending.
Sending 32bits works great.
Here is code for sending:

#include <SPI.h>

SPISettings settings(1000000, MSBFIRST, SPI_MODE0);

void setup()
{
  SPI1.setMOSI(26);
  SPI1.setMISO(1);
  SPI1.setSCK(27);
  SPI1.setCS(0);
  SPI1.begin();
}

void loop()
{
  delay(100);
 SPI1.beginTransaction(settings);
SPI1.transfer32(0b11100000000000000000000000000111);
SPI1.endTransaction();
}

Result: