C compilers for 8051 Chin-Shiuh Shih

C compilers for 8051 –SDCC - Small Device C Compiler –Raisonance RIDE-51 –Keil –… Some issues in using 8051 C compilers –Access to SFR (Special Function Register) –Implement Interrupt Service Subroutine –Memory allocation in variable declaration –…

SDCC - Small Device C Compiler SDCC - Small Device C Compiler is a free C compiler for 8051, although library is incomplete. Download sdcc setup.exe and install.

Issue "sdcc test.c" within DOS box will generate "test.ihx" in Intel-HEX format. Issue "sdcc --code-loc 0x xram-loc 0x8000 test.c" within DOS box will generate "test.ihx" in Intel-HEX format. –Option "--code-loc 0x4000" is used to specify starting code address. –Option "--xram-loc 0x8000" is used to specify the starting address of external data memory.

Refer to "c:\sdcc\share\doc\sdcc\sdccman.pdf" for SDCC Compiler User Guide. uart.c is a UART library by Chin-Shiuh Shieh, including Character, String, and Integer I/O. Refer to sample.c for its usage.

// Template for SDCC 8051 C Language #include // Definitions of registers, SFRs and Bits // ISR Prototypes =================================================== void INT0_ISR(void) interrupt 0; // ISR for External Interrupt 0 void T0_ISR(void) interrupt 1; // ISR for Timer0/Counter0 Overflow void INT1_ISR(void) interrupt 2; // ISR for External Interrupt 1 void T1_ISR(void) interrupt 3; // ISR for Timer1/Counter1 Overflow void UART_ISR(void) interrupt 4; // ISR for UART Interrupt void main(void) { } void INT0_ISR(void) interrupt 0 {} void T0_ISR(void) interrupt 1 {} void INT1_ISR(void) interrupt 2 {} void T1_ISR(void) interrupt 3 {} void UART_ISR(void) interrupt 4 {}

Input –P1=0xFF; –A=P1; Output –P2=0xF5;

Check button in assembly CHECK_BUTTON: JBP3.2,CBRET ;Task for button pressed WAIT_BUTTON_RELEASE: JNB P3.2,WAIT_BUTTON_RELEASE CBRET: Check button in C if(P3_2==0) { … while(P3_2==0); }

Wait button in assembly WAIT_BUTTON: JBP3.2,WAIT_BUTTON WAIT_RELEASE: JNBP3.2,WAIT_RELEASE Wait button in C while(P3_2==1); while(P3_2==0);

Left Rotation  Left Rotation in assembly RL A Left Rotation in C unsigned char i; if(i>=128) i=i*2+1; else i=i*2;

Right Rotation  Right Rotation in assembly RR A Right Rotation in C unsigned char i; if(i%2==1) i=i/2+128; else i=i/2;

data unsigned char test_data; xdata unsigned char test_data; xdata at 0x7ffe unsigned int chksum; idata unsigned char test_data; code unsigned char test_code; bit test_bit;

xdata at 0x0000 unsigned char ADC; ADC=0; X=ADC;

xdata at 0x3000 unsigned char x[1024]; for(i=0;i<1024;i++) –x[i]=i;