sdcc-extra/historygraphs/hello-mcs51/hello.c

   1 // Source by Philipp Krause under CC0 1.0
   2
   3 // A "Hello, World!"-Program. We use it to make the board
   4 // output something that can not be mistaken for output
   5 // From a benchmark.
   6
   7 #include <stdio.h>
   8
   9 #include <C8051F120.h>
  10
  11 int putchar(int c)
  12 {
  13         while(!(SCON0 & 0x02));
  14         SCON0 &= ~0x02;
  15         SBUF0 = c;
  16         return (c);
  17 }
  18
  19 unsigned char _sdcc_external_startup(void)
  20 {
  21         // Disable watchdog timer
  22         WDTCN = 0xde;
  23         WDTCN = 0xad;
  24
  25         return 0; // perform normal initialization
  26 }
  27
  28 void main(void)
  29 {
  30         unsigned long int i = 0;
  31
  32         // Initialize I/O pins
  33         SFRPAGE = 0xf;
  34         XBR0 = 0x04;                            // UART0 on P0.0 and P0.1
  35         P0MDOUT = 0x01;                         // Set port P0.0 (Uart tx) to push-pull
  36         XBR2 = 0x40;                            // Enable crossbar
  37
  38         OSCICN = 0xc3;                          // Run at full 24.5 Mhz - gives better accuracy for baudrate
  39
  40         // Use PLL to get SYSCLK to 98 Mhz to get reliable 9800 baud
  41         SFRPAGE = 0x0;
  42         FLSCL = 0xb0;
  43         SFRPAGE = 0xf;
  44         PLL0CN = 0x01;
  45         PLL0FLT = 0x01;
  46         PLL0MUL = 0x04;
  47         for (i = 0; i < 31; i++) // Wait 5 µs
  48         {
  49           __asm
  50           nop
  51           nop
  52           nop
  53           nop
  54           __endasm;
  55         }
  56         PLL0CN = 0x03;
  57         while (!(PLL0CN & 0x10));
  58         CLKSEL = 0x02;
  59
  60         // Configure UART for 1200 baud, 8 data bits, 1 stop bit.
  61         SFRPAGE = 0x0;
  62         TMOD = 0x21;
  63         SCON0 = 0x40;
  64         TH1 = 203;
  65         TCON |= 0x40;
  66         SCON0 |= 0x02;                          // Tell putchar() the UART is ready to send.
  67
  68         for(;;)
  69         {
  70                 printf("Hello, World!\n");
  71                 for(i = 0; i < 147456; i++); // Sleep
  72         }
  73 }
  74