Easy-Downloader V1.1 with SDCC

文章摘要：Sdcc has no putchar( ) function, so we must build it before we can use. I wrote a simple putchar( ) as my assembly code. void putchar(char c) { while(!TI); TI=0; SBUF = c; }We test TI bit before we can write a byte to SBUF. While TI is not set (buffer is not free) keep polling it, when it set,

Easy-Downloader V1.1 with SDCC,标签：电路图讲解,电路图练习,http://www.88dzw.com
Sdcc has no putchar( ) function, so we must build it before we can use. I wrote a simple putchar( ) as my assembly code.
 

void putchar(char c) {  while(!TI);   TI=0;  SBUF = c; }

We test TI bit before we can write a byte to SBUF. While TI is not set (buffer is not free) keep polling it, when it set, clear it and write a byte to SUF.

The same as putchar( ) function, I had built the getchar( ) for this board to make it compatible with old version.
 

char getchar(void) {  char c;  while(!RI);  RI =0;  c = SBUF;  putchar(c);    // echo to terminal  return SBUF; }

Now the code polls the RI bit, when it set, clear it and read SBUF and simply echo the received character with putchar( ) function.

The important function is getnum ( ) function. Let me explain how it works?
 

unsigned int getnum() {     char s[6];      char c;     char i;     unsigned int temp16;   c = 0;  i=0;   for (i = 0; c != 0xa; i++) // loop until CR has entered     {          putchar(xon); // send xon to signal host to send byte         c = getchar(); // get character from serial port   if(c == 0xd) c=0xa; // convert CR to LF to make it compatible with ez31 and ez41         s[i] = c; // save character to array     }     s[i-1] = 0; // put terminator at the end of string // convert ascii to integer (atoi(s))   temp16 = 0;  for(i=0; s[i] != 0; i++) temp16 = 10*temp16 + s[i]-'0';     return temp16; // return 16-bit for number of byte counting }

Look at the red one, it is a simple for loop with condition to check the received character is NEWLINE or not. If not it will save the character being received to array s[i]. The putchar(xon) sends the xon to host to let it know the board is ready to receive a byte. The getchar( ) is not echo the received byte. However it converts CF to LF. When the loop found LF or 0xa, it will exit from the for loop and save terminator byte to s[i-1].

The ascii string that saved in array s[] will be converted to 16-bit number with atoi code.

Most of the high level code are the same as previous version with Micro-C. You may study them in the source code then.

Let me shows you how to use sdcc to compile the source code again. The sample below uses batch file, s.bat.
 

C:\sdcc\app>s C:\sdcc\app>path=c:\sdcc\bin C:\sdcc\app>sdcc writer1.c library file /sdcc/share/sdcc/lib/small/libsdcc.lib library file /sdcc/share/sdcc/lib/small/libint.lib library file /sdcc/share/sdcc/lib/small/liblong.lib library file /sdcc/share/sdcc/lib/small/libfloat.lib C:\sdcc\app>packihx writer1.ihx>writer1.hex packihx: read 166 lines, wrote 75: OK. C:\sdcc\app>

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Tag:单片机电路图，电路图讲解,电路图练习，电子电路图 - 单片机电路图