// Rapsberry Pi: SPI con wiring Pi - Versione 1.2 - Marzo 2018
// Copyright (c) 2013-2018, Vincenzo Villa
// Creative Commons | Attribuzione - Condividi allo stesso modo 4.0 Internazionale (CC BY-SA 4.0)
// Creative Commons | Attribution-Share Alike 4.0 Unported
// https://www.vincenzov.net/tutorial/RaspberryPi/spi-wpi.htm

// MCP3202 (SPI ADC)
// wirinPi 2.44
// Linux raspberrypi 9.4 

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include "wiringPi.h"
#include "wiringPiSPI.h"
#include <linux/spi/spidev.h>


#define SPI_CLOCK 1000000     // 1 MHz
#define MCP3202_CH 1          // /dev/spidev0.1
#define VREF 3.3              // Voltage referenze (= VDD)
#define COUNT 4096            // 2 ^ 12


// See MCP3202 data sheet FIGURE 6-1 SPI Communication using 8-bit segments
#define MCP3202_START 1       // 0000 0001 
#define MCP3202_CONFIG  0xA0  // 101x xxxx (Single-Ended + Channel 0 + MSB first)
#define MCP2002_BUFFER_SIZE 3

int main(int argc, char** argv) {

    uint8_t buffer[MCP2002_BUFFER_SIZE]; // See FIGURE 6-1 on data sheet
    int error; // From wirinPi library
    double voltage; // Voltage from ADC
    int ADC;        // Voltage from ADC, as integer 0 -> 4095

    setbuf(stdout, NULL); // NetBeans hack: disable buffering on stdout

    error = wiringPiSPISetup(MCP3202_CH, SPI_CLOCK); // Set SPI clock
    
    // if (error ....)

    buffer[0] = MCP3202_START; // Set output buffrt with MCP3202 configuration
    buffer[1] = MCP3202_CONFIG;
    buffer[2] = 0;

    wiringPiSPIDataRW(MCP3202_CH, buffer, MCP2002_BUFFER_SIZE); // Read and write buffer

    ADC = (buffer[2] | ((buffer[1] & 0x0F) << 8));
    
    voltage = 3.3 / COUNT * ADC; // Convert to 12 bit result
    
    printf("Data read: 0x%02hhx 0x%02hhx 0x%02hhx -> %d -> %4.3f V\n", buffer[0], buffer[1], buffer[2], ADC, voltage);

    return (EXIT_SUCCESS);
}