Tranferring string over SPI Extended mode

Projects General Guidance
1

Dear Community,

I'd like to use the SPI interface of the ArduinoDUE to transfer a 100byte string using the extended SPI method

The problem is I don't know hot to convert my string in SPI data. Can I have an hint on how proceed with this task?

Best,
CorteX

2

Transfer all chars or bytes in your string using SPI_CONTINUE, except for the last one. Eventually you have to add a (byte) or (uint8_t) type cast to the char, if transfer() insists in only transfering bytes.

If you have C strings of variable size, you can transfer all chars in a loop, until you hit the terminating zero. Then break out of the loop, and send the final zero.

3

Dear DrDiettrich,

many thanks, can you write, please, that code because I'm new to arduino programming.
Basically I have to.

  • convert the sting to char (or byte array)
  • go through the array with a for loop (or while if I insert a termination character)
  • Transfer with SPI_CONTINUE

am I right?

CorteX

4

A string conversion is not normally required, a type cast should be sufficient. More could be said if you present your code.

5

You could code something like that, from reply #35, to transfer 100 bytes in 19 us:

TurboSpi

6

Dear DrDiettrich and ard_newbie,

here is the part of the code we are discussing: basically I have a DWM1000 receiver that put data inside "message" and send it over serial. I want to send that data over SPI to an FPGA.

#include <SPI.h>
#include <DW1000.h>

// connection pins
const uint8_t PIN_RST = 9; // reset pin
const uint8_t PIN_IRQ = 2; // irq pin
const uint8_t PIN_SS = SS; // spi select pin

// DEBUG packet sent status and count
volatile boolean received = false;
volatile boolean error = false;
volatile int16_t numReceived = 0; // todo check int type
String message;

void setup() {
  // DEBUG monitoring
  Serial.begin(250000);
  Serial.println(F("### DW1000-arduino-receiver-test ###"));
  // initialize the driver
  DW1000.begin(PIN_IRQ, PIN_RST);
  DW1000.select(PIN_SS);
  Serial.println(F("DW1000 initialized ..."));
  // general configuration
  DW1000.newConfiguration();
  DW1000.setDefaults();
  DW1000.setDeviceAddress(6);
  DW1000.setNetworkId(10);
  DW1000.enableMode(DW1000.MODE_SHORTDATA_FAST_ACCURACY);
  DW1000.commitConfiguration();
  Serial.println(F("Committed configuration ..."));
  // DEBUG chip info and registers pretty printed
  char msg[128];
  DW1000.getPrintableDeviceIdentifier(msg);
  Serial.print("Device ID: "); Serial.println(msg);
  DW1000.getPrintableExtendedUniqueIdentifier(msg);
  Serial.print("Unique ID: "); Serial.println(msg);
  DW1000.getPrintableNetworkIdAndShortAddress(msg);
  Serial.print("Network ID & Device Address: "); Serial.println(msg);
  DW1000.getPrintableDeviceMode(msg);
  Serial.print("Device mode: "); Serial.println(msg);
  // attach callback for (successfully) received messages
  DW1000.attachReceivedHandler(handleReceived);
  DW1000.attachReceiveFailedHandler(handleError);
  DW1000.attachErrorHandler(handleError);
  // start reception
  receiver();
}

void handleReceived() {
  // status change on reception success
  received = true;
}

void handleError() {
  error = true;
}

void receiver() {
  DW1000.newReceive();
  DW1000.setDefaults();
  // so we don't need to restart the receiver manually
  DW1000.receivePermanently(true);
  DW1000.startReceive();
}

void loop() {
  // enter on confirmation of ISR status change (successfully received)
  if (received) {
    
    // get data as string
    DW1000.getData(message);
   
    Serial.println(message);
    
    // !!!!!!!!!!!!HERE COMES SPI TRANFERRING 2 FPGA !!!!!!!!!!!!!!!!!!!1

    received = false;
  }
  if (error) {
    Serial.println("Error receiving a message");
    error = false;
    DW1000.getData(message);
    Serial.print("Error data is ... "); Serial.println(message);
  }
}

Basically the Turbo SPI is something I like VERY much but I have the DWM1000 still on SPI and I have to check if that device still works...

How can I cast efficently from string to uint8_t?

CorteX

7

Try to send message.length() chars from message.c_str(). See String reference for more information.