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hi i am trying to interface an 16x2 lcd onto an arm7 board lpc2148. the pins i am using for the data is p0.16-p0.23 and for control signals ie rs rw e i am using p1.24 p1.25 p1.26 respectively.When i dump the following code nothing is getting changed in the display .can anybody help me out...i am attaching the code here ..kindly do the needful
#include<LPC214x.h> void init_PLL(void); void init_GPIO(void); void lcd_data(unsigned char); void lcd_cmd(unsigned char); void lcd_init(void); void delay(unsigned int); #define E 0x04000000 #define RW 0x02000000 #define RS 0x01000000 int main(void) { init_PLL(); init_GPIO(); lcd_init(); while(1) { lcd_data('A'); lcd_data('B'); lcd_data(96); lcd_data('d'); delay(0xffffff); } } void init_PLL(void) { PLL0CFG=0x00000024; // TO GENERATE 60 MHZ CCLK PLL0CON=0x00000001; PLL0FEED=0x000000AA;//UPDATE THE PLL REGISTER PLL0FEED=0x00000055; while(!(PLL0STAT & 0x00000400)); // CHECK WHETHRT THE CCLK IS GENERATED EXAXT VALUE PLL0CON=0x00000003; // CONNECT PLL PLL0FEED=0x000000AA; //UPDATE THE PLL REGISTER PLL0FEED=0x00000055; VPBDIV=0x00000002; //PCLK=1/2*CCLK } void init_GPIO( void) { PINSEL0=0x00FF0000; PINSEL1=0x07000000; IODIR0=0x00FF0000; IODIR1=0x07000000; } void lcd_init(void) { lcd_cmd(0x380000); delay(0xffffff); lcd_cmd(0x0e0000); delay(0xffffff); lcd_cmd(0x800000); delay(0xffffff); lcd_cmd(0x060000); delay(0xffffff); } unsigned int adjust_portbit(unsigned char c) { unsigned char j; unsigned int result; result=c; for(j=0;j<16;j++) { result=result<<1; } return result; } void lcd_data(unsigned char ldata) { unsigned int temp,z; temp=adjust_portbit(ldata); init_GPIO(); z=~temp; IOCLR1=z; IOSET0=ldata; delay(0xffffff); IOCLR1=RW; IOSET1=RS; delay(0xffffff); IOSET1=E; delay(0xffffff); IOCLR1=E; } void lcd_cmd(unsigned char lcmd) { unsigned int temp,z; temp=adjust_portbit(lcmd); init_GPIO(); z=~temp; IOCLR1=z; IOSET0=lcmd; delay(0xffffff); IOCLR1=RW; IOCLR1=RS; IOSET1=E; delay(0xffffff); IOCLR1=E; } void delay(unsigned int value) { unsigned int i; for(i=0;i<value;i++); { } }
void delay()__arm { __asm { MOV R3,R0 loop: SUB R1,R1,#1 ;R1 = R1-1 NOP ;A more delaying SUB R0,R0,#1 ;R0 = R0-1 BNE loop ;BRANCH if NOW NOT NULLIFIED BX LR ;GO TO WHERE YOU CAME FROM } }
will this be fine
vikas, can you make up a convincing argument as to WHY you need to decrement both R0 and R1? only one of them will do! you also forgot to backup the value of the changed registers in the stack, and to pop the old value from the stack when done.
but mr tameer.
yo're code still used R0 and R1 and did not pre serve?
does ARM calling convections need you to store R0 and R1?
Zeusti.
Always yo're freind.
if you look at one of my previous posts, you would see that I indicated that mistake already. there is no need to decrement more than one register. the need to preserve/restore R0 and R1 stems from the fact that the caller might assume a different role/value for these registers, hence delaying your code without maintaining their old value might break your software one the call returns.
poor mr tameer.
read the apcs.