//-----------------------------------------------------------------------------
// EMIF_1.c
//-----------------------------------------------------------------------------
// Copyright 2001 Cygnal Integrated Products, Inc.
//
// AUTH: BW
// DATE: 11 DEC 01
//
// This program configures the external memory interface to read and write
// to an external SRAM mapped to the upper port pins.  Assumes an external
// 22.1184MHz crystal is attached between XTAL1 and XTAL2.
//
// Target: C8051F02x
// Tool chain: KEIL C51 6.03 / KEIL EVAL C51
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f020.h>                 // SFR declarations
#include <stdio.h>

//-----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F02x
//-----------------------------------------------------------------------------

sfr16 DP       = 0x82;                 // data pointer
sfr16 TMR3RL   = 0x92;                 // Timer3 reload value
sfr16 TMR3     = 0x94;                 // Timer3 counter
sfr16 ADC0     = 0xbe;                 // ADC0 data
sfr16 ADC0GT   = 0xc4;                 // ADC0 greater than window
sfr16 ADC0LT   = 0xc6;                 // ADC0 less than window
sfr16 RCAP2    = 0xca;                 // Timer2 capture/reload
sfr16 T2       = 0xcc;                 // Timer2
sfr16 RCAP4    = 0xe4;                 // Timer4 capture/reload
sfr16 T4       = 0xf4;                 // Timer4
sfr16 DAC0     = 0xd2;                 // DAC0 data
sfr16 DAC1     = 0xd5;                 // DAC1 data

//-----------------------------------------------------------------------------
// Global CONSTANTS
//-----------------------------------------------------------------------------

#define SYSCLK       22118400          // SYSCLK frequency in Hz
#define BAUDRATE     115200            // Baud rate of UART in bps

#define RAM_BANK     0x20;             // bank select bit is P4^5
#define RAM_CS       0x10;             // chip select bit is P4^4

sbit LED = P1^6;                       // LED = 1 means ON

//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------

void SYSCLK_Init (void);
void PORT_Init (void);
void UART0_Init (void);
void EMIF_Init (void);

//-----------------------------------------------------------------------------
// Global VARIABLES
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------

void main (void) {

   unsigned char xdata *pchar;         // memory access pointer
   unsigned long i;

   WDTCN = 0xde;                       // disable watchdog timer
   WDTCN = 0xad;

   SYSCLK_Init ();                     // initialize oscillator
   PORT_Init ();                       // initialize crossbar and GPIO
   UART0_Init ();                      // initialize UART0
   EMIF_Init ();                       // initialize memory interface

   P4 &= ~RAM_BANK;                    // select lower bank
   P4 &= ~RAM_CS;                      // assert RAM chip select

   // clear xdata space
   pchar = 0;
   for (i = 0; i < 65536; i++) {
      *pchar++ = 0;
      // print status to UART0
      if ((i % 16) == 0) {
         printf ("\nwriting 0x%04x: %02x ", (unsigned) i, (unsigned) 0);
      } else {
         printf ("%02x ", (unsigned) 0);
      }
   }

   // verify all are zero
   pchar = 0;
   for (i = 0; i < 65536; i++) {
      if (*pchar != 0) {
         printf ("Erase error!\n");
         while (1);
      }
      // print status to UART0
      if ((i % 16) == 0) {
         printf ("\nverifying 0x%04x: %02x ", (unsigned) i, (unsigned) *pchar);
      } else {
         printf ("%02x ", (unsigned) *pchar);
      }
      pchar++;
   }

   // write xdata space
   pchar = 0;
   for (i = 0; i < 65536; i++) {
      *pchar = ~i;
      // print status to UART0
      if ((i % 16) == 0) {
         printf ("\nwriting 0x%04x: %02x ", (unsigned) i, (unsigned) ((~i) & 0xff));
      } else {
         printf ("%02x ", (unsigned) ((~i) & 0xff));
      }
      pchar++;
   }

   // verify 
   pchar = 0;
   for (i = 0; i < 65536; i++) {
      if (*pchar != ((~i) & 0xff)) {
         printf ("Verify error!\n");
         while (1);
      }
      // print status to UART0
      if ((i % 16) == 0) {
         printf ("\nverifying 0x%04x: %02x ", (unsigned) i, (unsigned) *pchar);
      } else {
         printf ("%02x ", (unsigned) *pchar);
      }
      pchar++;
   }

   while (1);
}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clock to use an 22.1184MHz crystal
// as its clock source.
//
void SYSCLK_Init (void)
{
   int i;                              // delay counter

   OSCXCN = 0x67;                      // start external oscillator with
                                       // 22.1184MHz crystal


   for (i=0; i < 256; i++) ;           // wait for oscillator to start

   while (!(OSCXCN & 0x80)) ;          // Wait for crystal osc. to settle

   OSCICN = 0x88;                      // select external oscillator as SYSCLK
                                       // source and enable missing clock
                                       // detector
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{
   XBR0    |= 0x04;                    // Enable UART0
   XBR2    |= 0x40;                    // Enable crossbar and weak pull-ups
   P0MDOUT |= 0x01;                    // enable TX0 as a push-pull output
   P1MDOUT |= 0x40;                    // enable LED as push-pull output
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Configure the UART0 using Timer1, for <baudrate> and 8-N-1.
//
void UART0_Init (void)
{
   SCON0  = 0x50;                      // SCON0: mode 1, 8-bit UART, enable RX
   TMOD   = 0x20;                      // TMOD: timer 1, mode 2, 8-bit reload
   TH1    = -(SYSCLK/BAUDRATE/16);     // set Timer1 reload value for baudrate
   TR1    = 1;                         // start Timer1
   CKCON |= 0x10;                      // Timer1 uses SYSCLK as time base
   PCON  |= 0x80;                      // SMOD00 = 1
   TI0    = 1;                         // Indicate TX0 ready
}

//-----------------------------------------------------------------------------
// EMIF_Init
//-----------------------------------------------------------------------------
//
// Configure the external memory interface to use upper port pins in 
// non-multiplexed mode to a mixed on-chip/off-chip configuration without 
// Bank Select.
//
void EMIF_Init (void)
{
   EMI0CF = 0x3c;                      // upper ports; non-muxed mode;
                                       // split mode w/o bank select
   EMI0TC = 0x00;                      // fastest timing (4-cycle MOVX)
   P74OUT |= 0xfe;                     // all EMIF pins configured as
                                       // push-pull
}