#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"
#include "hardware/spi.h"

/*
  Our 7 Segment display has pins as follows:
  --A--
  F   B
  --G--
  E   C
  --D--
*/

// using default SPI0 on pins GP16 (SPI RX/MISO), GP18 (SCK) and GP19 (SPI TX/MOSI)
const unsigned int mosi = 19;
const unsigned int sck = 18;
const unsigned int cs = 7;

spi_inst_t *spi = spi0;  // make sure spi is spi0

// This array converts a number 0-9 to a bit pattern to send to the GPIO's
int bits[10] = {
        0x3f,  // 0
        0x06,  // 1
        0x5b,  // 2
        0x4f,  // 3
        0x66,  // 4
        0x6d,  // 5
        0x7d,  // 6
        0x07,  // 7
        0x7f,  // 8
        0x67   // 9
};

void main() {
  spi_init(spi, 500*1000);
  gpio_set_function(cs, GPIO_FUNC_SIO);
  gpio_set_dir(cs, GPIO_OUT);
  // Make sure the CS is low at start
  gpio_put(cs, 0);

  gpio_set_function(sck,  GPIO_FUNC_SPI);
  gpio_set_function(mosi, GPIO_FUNC_SPI);
  sleep_ms(1000);

  uint8_t val = 0;
  while(1) {
      if (val == 9) val = 0;
      else val++;
      // Get mask - common anode so need to put 0 out to turn LED segment on.
      unsigned char mask = ~bits[val];
      char str[25];

      // Set all our GPIO's in one go!
      spi_write_blocking(spi, &mask, 1);
  
      // pulse the CS to put data in shift register out
      gpio_put(cs, 1);
      sleep_ms(50);
      gpio_put(cs, 0);

      sleep_ms(950);
  }
}