Return to Question

added 1726 characters in body

Source Link

edited Oct 22, 2019 at 10:15

The master's code I plan to use:

const int CLOCK_PIN = 2;
const int DATA_PIN = 3;
const int BIT_COUNT = 16;  
void setup() {
    pinMode(DATA_PIN, INPUT);
    pinMode(CLOCK_PIN, OUTPUT);
    digitalWrite(CLOCK_PIN, HIGH);
    Serial.begin(115200);
  }
void loop() {
    float reading = readPosition();
    Serial.println(reading,2);
    delay(25);
  }

//read the current angular position
float readPosition() {
 unsigned long graysample = shiftIn(DATA_PIN, CLOCK_PIN, BIT_COUNT);
 delayMicroseconds(100); // Clock must be high for 20 microseconds before a new sample can be taken
unsigned long binarysample = grayToBinary32(graysample);
 return ((binarysample * 360UL) / 65536.0); // ouptut value from 0 to 360 with two point percision
}
//read in a byte of data from the digital input of the board.
unsigned long shiftIn(const int data_pin, const int clock_pin, const int bit_count) {
 unsigned long data = 0;
 for (int i=0; i<bit_count; i++) {
 data <<= 1; // shift all read data left one bit.

 //digitalWrite(clock_pin,LOW);
 PORTD &= ~(1 << 5); // clock pin goes low
 delayMicroseconds(1);
 //digitalWrite(clock_pin,HIGH);
 PORTD |= (1 << 5); // lock pin goes high
 delayMicroseconds(1);
 data |= digitalRead(data_pin); // cat the new read bit to the whole read data.
 }
 return data;
}
unsigned int grayToBinary32(unsigned int num)
{
 num = num ^ (num >> 16);
 num = num ^ (num >> 8);
 num = num ^ (num >> 4);
 num = num ^ (num >> 2);
 num = num ^ (num >> 1);
 return num;
}

The master's code I plan to use:

const int CLOCK_PIN = 2;
const int DATA_PIN = 3;
const int BIT_COUNT = 16;  
void setup() {
    pinMode(DATA_PIN, INPUT);
    pinMode(CLOCK_PIN, OUTPUT);
    digitalWrite(CLOCK_PIN, HIGH);
    Serial.begin(115200);
  }
void loop() {
    float reading = readPosition();
    Serial.println(reading,2);
    delay(25);
  }

//read the current angular position
float readPosition() {
 unsigned long graysample = shiftIn(DATA_PIN, CLOCK_PIN, BIT_COUNT);
 delayMicroseconds(100); // Clock must be high for 20 microseconds before a new sample can be taken
unsigned long binarysample = grayToBinary32(graysample);
 return ((binarysample * 360UL) / 65536.0); // ouptut value from 0 to 360 with two point percision
}
//read in a byte of data from the digital input of the board.
unsigned long shiftIn(const int data_pin, const int clock_pin, const int bit_count) {
 unsigned long data = 0;
 for (int i=0; i<bit_count; i++) {
 data <<= 1; // shift all read data left one bit.

 //digitalWrite(clock_pin,LOW);
 PORTD &= ~(1 << 5); // clock pin goes low
 delayMicroseconds(1);
 //digitalWrite(clock_pin,HIGH);
 PORTD |= (1 << 5); // lock pin goes high
 delayMicroseconds(1);
 data |= digitalRead(data_pin); // cat the new read bit to the whole read data.
 }
 return data;
}
unsigned int grayToBinary32(unsigned int num)
{
 num = num ^ (num >> 16);
 num = num ^ (num >> 8);
 num = num ^ (num >> 4);
 num = num ^ (num >> 2);
 num = num ^ (num >> 1);
 return num;
}

Source Link

asked Oct 21, 2019 at 12:44

floppy380

How to modify this code to simulate a binary encoder?

I have come across the following SPI slave code at this site:

#include <SPI.h>

char buf [100];
volatile byte pos;
volatile bool process_it;

void setup (void)
{
  Serial.begin (115200);   // debugging

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

  // have to send on master in, *slave out*
  pinMode (MISO, OUTPUT);

  // get ready for an interrupt
  pos = 0;   // buffer empty
  process_it = false;

  // now turn on interrupts
  SPI.attachInterrupt();

}  // end of setup


// SPI interrupt routine
ISR (SPI_STC_vect)
{
byte c = SPDR;  // grab byte from SPI Data Register

  // add to buffer if room
  if (pos < sizeof buf)
    {
    buf [pos++] = c;

    // example: newline means time to process buffer
    if (c == '\n')
      process_it = true;

    }  // end of room available
}  // end of interrupt routine SPI_STC_vect

// main loop - wait for flag set in interrupt routine
void loop (void)
{
  if (process_it)
    {
    buf [pos] = 0;
    Serial.println (buf);
    pos = 0;
    process_it = false;
    }  // end of flag set

}  // end of loop

How to modify the above code so that it responds to input clock signal just like in this SSI protocol? Uno or Nano can be used.

Basically I want to let an arduino act as an absolute encoder so that it will transmit 13-bit binary data(it can be any random fixed binary data) as shown in the above SSI protocol. So the Arduino will output 13-bit binary data along with with start bit and tm taken into account as shown in the document above without parity.

arduino-uno arduino-nano