void spi_init(int freq, int settings) {
     pin_mode(8, ALT0);   // CE0b
     pin_mode(9, ALT0);   // MISO
     pin_mode(10, ALT0);  // MOSI
     pin_mode(11, ALT0);  // SCLK
     SPI0CLK = 250000000/freq;
     SPI0CS = settings;
     SPICSbits.TA = 1; // turn SPI on
}

char spi_sendrecv(char data) {
     SPI0FIFO = send;
     while (!SPI0CSbits.DONE) ;
     return SPI0FIFO;
}

void uart_init(int baud) {
  uint fb = 12000000/baud;      // 3 MHz UART clock
  pinMode(14, ALT0);            // TX
  pinMode(15, ALT0);            // RX
  UART_IBRD = fb >> 6;          // 6 Fract, 16 Int bits of BRD
  UART_FBRD = fb & 63;
  UART_LCRHbits.WLEN = 3;       // 8 Data, 1 Stop, no Parity, no FIFO, no Flow
  UART_CRbits.UARTEN = 1;       // Enable uart
}

char getchar_serial(void) {
  while (UART_FRbits.RXFE);     // Wait until data is available
  return UART_DRbits.DATA;      // Return char from serial port
}
void putchar_serial(char c) {
  while (!UART_FRbits.TXFE);    // Wait until ready to transmit
  UART_DRbits.DATA = c;         // Send char to serial port
}

#define MAX_STR_LEN 80
void getstr_serial(char *str) {
  int i = 0;
  do {                          // Read an entire string until
    str[i] = getchar_serial();  // Carriage return
  } while ((str[i++ ] ! = '\r')
          && (i < MAX_STR_LEN));// Look for carriage return
  str[i-1] = 0;                 // Null-terminate the string
}
void putstr_serial(char *str) {
  int i = 0;
  while (str[i] ! = 0) {        // Iterate over string
    putchar_serial(str[i++ ]);    // Send each character
  }
}