# SPISettings

The SPISettings object is used to configure the SPI port for your SPI device. You can also configure the SPI separately see SPI.setClockDivider(), SPI.setBitOrder() and SPI.setDataMode()

# Syntax

// Javascript Format
settings = new linuxduino.SPISettings(speedMaximum, dataOrder, dataMode);
// C++ Format
SPISettings mySettting(speedMaximum, dataOrder, dataMode)

# Parameters

speedMaximum:
The maximum SPI clock speed.

Available speeds:

SPI_CLOCK_DIV2: SPI clock to 8000000 (8 Mhz)
SPI_CLOCK_DIV4: SPI clock to 4000000 (4 Mhz)
SPI_CLOCK_DIV8: SPI clock to 2000000 (2 Mhz)
SPI_CLOCK_DIV16: SPI clock to 1000000 (1 Mhz)
SPI_CLOCK_DIV32: SPI clock to 500000 (500 khz)
SPI_CLOCK_DIV64: SPI clock to 250000 (250 khz)
SPI_CLOCK_DIV128: SPI clock to 125000 (125 khz)

dataOrder:
Data order when transmitting

Available data orders:
LSBFIRST: Sends least significant bit first.
MSBFIRST: Sends most significant bit first.

dataMode: Clock and Sampling configurations.

Available data modes:
SPI_MODE0: Clock Idle low -> CPOL=0, First edge Sampling -> CPHA=0
SPI_MODE1: Clock Idle low -> CPOL=0, Second edge Sampling -> CPHA=1
SPI_MODE2: Clock Idle high -> CPOL=1, First edge Sampling -> CPHA=0
SPI_MODE3: Clock Idle high -> CPOL=1, Second edge Sampling -> CPHA=1

# Returns

None

# Example

# Javascript

const linuxduino = require('linuxduino');

// Testing SPI beginTransaction
(async() => {
  // Wait for wasm file
  await linuxduino.ready;
  
  // Open SPI port
  SPI = new linuxduino.SPI();
  SPI.begin("/dev/spidev0.0");

  // Set SPI Settings
  settingsA = new linuxduino.SPISettings(linuxduino.SPI_CLOCK_DIV64, 
    linuxduino.MSBFIRST, linuxduino.SPI_MODE3);

  // Send Hello World! every second
  buff = Buffer.from("Hello World!\n");
  var ret;
  while(1) {
    SPI.beginTransaction(settingsA);
    // Note in SPI the last character will not be printed here. 
    // In SPI you recieve what you sent previously. 
    for(var i=0; i<buff.length; i++) {
      ret = SPI.transfer(buff[i]); // Transmit and receive one byte
      process.stdout.write(String.fromCharCode(ret));
    }
    SPI.endTransaction();
    process.stdout.write('\n');
    linuxduino.delay(1000); // delay 1 sec.
  }
  
  SPI.end();
})();

Run it

sudo node spi_beginTransaction.js

# C++

#include "Linuxduino.h"

// Testing SPI beginTransaction
int main(void) {

    char ret;

    // Open SPI port
    SPI.begin("/dev/spidev0.0");

    // Set SPI Settings
    SPISettings settingsA(SPI_CLOCK_DIV64, MSBFIRST, SPI_MODE3);

    // Send Hello World! every second
    while(1) {
        SPI.beginTransaction(settingsA);
        // Note in SPI the last character will not be printed here. 
        // In SPI you recieve what you sent previously. 
        for (const char *p = "Hello, world!\n" ; *p!=0 ; p++) {
            ret = SPI.transfer (*p); // Transmit and receive one byte
            printf("%c", ret);
        }
        SPI.endTransaction();
        printf("\n");        
        delay(1000); // delay 1 sec.
    }

    SPI.end(); 
    return 0;
}

Run it

g++ spi_beginTransaction.cpp -o spi_beginTransaction -llxduino
sudo ./spi_beginTransaction