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I want to have a simple program to print something out using hyperterminal. Also it would be nice to receive a character and echo it back. I have been able to do this in assembly but I can't get it to work in C. Here is the latest code I have tried:
#include <AT89X51.H> #include <CTYPE.H> #include <STDIO.H> int i; void main() { SCON = 0x50; //SCON: mode 1, 8-bit UART, enable rcvr TMOD = 0x20; //TMOD: timer 1, mode 2, 8-bit reload TH1 = 0xFD; //TH1: reload value for 9600 baud @ 11.0592MHz TR1 = 1; //TR1: timer 1 run TI = 1; //TI: set TI to send first char of UART while (1) { P1 ^= 0x01; printf ("\n\nHello World\n\n"); i = _getkey(); putchar('$'); putchar(i); } }
"What would I want to change in the GETKEY.C and PUTCHAR.C source files?" The standard versions are not interrupt-driven, and use the "standard" 8051 SBUF, etc; so you'd want to change them if this was unsuitable - eg, you want to use a different serial port.
Thanks for the suggestion. The 'standard' SBUF is fine with me, and I'm not trying to do anything with interrupts yet. Do I need to include any header files or link with some source files when I compile?
These are the signatures of putchar and getkey; char putchar (char c); char _getkey (); neither Function returns, unless the character is read/written You might use your assembler routines wihtin these Templates:
?PR?PUTCHAR?PUTCHAR SEGMENT CODE RSEG ?PR?PUTCHAR?PUTCHAR PUBLIC (_PUTCHAR) _PUTCHAR: ;; output a Character and don't return, until the character ;; is output. ;; when invoked from C, the ;; character will be passed in Register R7 ;; Your Assembly Code here MOV R7,#<the caharcter you actually wrote> ;; return value RET
?PR?_GETKEY?GETKEY SEGMENT CODE RSEG ?PR?_GETKEY?GETKEY PUBLIC (_GETKEY) _GETKEY: ;; get a Character and don't return, until the character ;; is input. ;; when invoked from C, the ;; character will be expected in Register R7 ;; Your Assembly Code here MOV R7,#<the caharcter you actually wrote> ;; return value RET
... something: of course include these Declarations:
extern char putchar (char c); extern char _getkey ();
T
T function (void);
_function:
I included <stdio.h> in my code. I found the declarations in that header file. Will this take care of that problem. Also do I need to add the header files I use to my source group or another group on the left of the window? Thanks for the help. Jake
"...do I need to add the header files..." No, you don't need to add them. However, you might find it useful to add them; eg, to give quick access to open a frequently-used header. In that case, you'd need to clear the 'Include in Build' option - otherwise uVision will try to separately compile your header(s)!!
stdio.h will do. You can understand the #include - control as a substitute of pasting the Text of the included File into the including module. The preprocessor of C doesn't anything else. If you costumize the functions, you must add your custom object file(s) to the list of objects to be linked. You're maybe talking about the "left window" of your IDE. I don't use an IDE for 8051 Projects. I just hack the text into files, using a text editor. Then invoke compiler and linker directly via Windows-Explorer and entries in the Registry:
[HKEY_CLASSES_ROOT\c_auto_file\shell\C51-Compiler_Emulator\command] @="C:\\C51\\BIN\\C51.EXE %1 DEFINE ( TEST_CODE = 1 ) OE PP"
I reviewed the messages and am not sure whether you tried stepping into your C program using the simulator. I have found this a good tool for both the asynch serial comm and the clocks. The simulator will show you how you have set the baud and will display sbuf. Run the simulator with your assy code and record the ports' setup bits. Run again with your C code and compare the ports' setup bits. This may allow you to confirm if you are setting up the ports properly.