Demo.c

#include <SI_EFM8BB1_Register_Enums.h>

#define SBUF  SBUF0

#define SCON  SCON0

#define TI    SCON0_TI

#define  TR1    TCON_TR1

// long delay

void delay (unsigned char val)

{

  volatile short idx, cnt;

  for (idx=0; idx<=val; idx++)

    for (cnt=0; cnt<=0x3FFF; cnt++);

}

// segment dot

sbit S7 = P1^3;

// serial send

void send(unsigned char ch)

{

  // add parity to char

  // unsigned char par = ((unsigned char) P) << 7;

  // SBUF = ch | par;

  // no partity

  SBUF = ch;

  while (!TI);  // wait until transmitted

  TI=0;

}

void init(void)

{

  // EFM8 specific serial configuration

  // P0.4 - UART0 TX - PUSH_PULL

  // P0.5 - UART0 RX - OPEN_DRAIN

  P0MDOUT |= (1 << (4));

  // EFM8 specific ADC configuration

  // P0.7 - ADC0

  P0MDIN &= ~(1 << (7));  // set P0.7 to analog input

  P0SKIP |= (1 << (7));    // disconnect P0.7 from digital

  ADC0MX = 7;              // connect P0.7 to ADC0 via MUX

  // ADC0 configuration - %00001|1|0|1 - SYSCLK/(1+1)|8-bit mode|no delay|gain=1

  ADC0CF = 0x0D;

  REF0CN = 0x08;          // voltage reference is VDD=3.3V

  ADC0CN0 |= (1 << (7));  // enable ADC0

  // SYSCLK = HFOSC0 = 24.5 MHz

  // SYSCLK = SYSCLK/1

  CLKSEL = 0;

  // timer 1 uses SYSCLK

  CKCON0 |= (1 << (3));

  XBR0 |= (1 << (0));  // cross-bar enable UART0 pins

  XBR2 |= (1 << (6));  // cross-bar enable all pins

  // 8051 serial configuration

  // UART mode %01 = 8-bit data

  SCON = 0x40;

  // timer 1 mode 2

  TMOD = 0x20;

  // Baud rate

  TH1 = 0x96;  // 256-150=106 - 24.5 MHz / 106 = 231132 / 2 = 115566 (115200 Baud 0.3% error)

  TL1 = 0x96;

  // timer 1 start

  TR1 = 1;

}

void main(void)

{

  unsigned short counter = 0;

  char ch, buffer[] = "-----";  // 4 decimal digits + CR terminal new line

  buffer[4] = 0x0D;              // CR terminal new line

  init();

  while (1)

  {

    unsigned char idx = 0;

    // ADC0 conversion

    ADC0CN0 |= (1 << (4));          // start conversion

    while ((ADC0CN0 & 0x10) == 0);  // wait for done

    ADC0CN0 &= ~(1 << (5));          // reset

    // CAUTION: 8-bit result is bits 9:2

    counter = ((ADC0H << 8) | ADC0L);

    counter >>= 2;    // 8-bit result

    // convert to ASCII

    buffer[0] = 0x30 + counter/1000;

    buffer[1] = 0x30 + (counter%1000)/100;

    buffer[2] = 0x30 + (counter%100)/10;

    buffer[3] = 0x30 + counter%10;

    while ((ch = buffer[idx++]) != 0)

      send(ch);

    // blink dot

    S7 ^= 1;

    delay(25);

  }

}