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@----------------------------------------------------------------------------
@ File Name : seriell.S
@ Object : Grundfunktionen der seriellen Schnittstelle
@
@ 1.0 27/10/02 GR : Creation
@----------------------------------------------------------------------------
.file "seriell.S"
#include "../h/pmc.inc"
#include "../h/pio.inc"
#include "../h/usart.inc"
DEFAULT_BAUD = 38400
CLOCK_SPEED = 25000000
US_BAUD = 0x29 @ CLOCK_SPEED / (16*(DEFAULT_BAUD))
@ Funktion
.text
.align 2
.global init_ser
.type init_ser,function
init_ser:
stmfd sp!, {r0-r3, lr} @ Register retten
adr r0,L1
adr r1,L1_end
init_ser_loop:
ldmia r0!, {r2-r3}
cmp r0, r1
str r3, [r2]
bne init_ser_loop
ldmfd sp!, {r0-r3, pc} @ R�cksprung
L1:
.word PMC_BASE+PMC_PCER, 0x4
.word PIOA_BASE+PIO_PDR, 0x18000
.word USART0_BASE+US_CR, 0xa0
.word USART0_BASE+US_MR, 0x8c0
.word USART0_BASE+US_BRGR, US_BAUD
.word USART0_BASE+US_CR, 0x50
L1_end:
@ Funktion
.text
.align 2
.global putchar
.type putchar,function
putchar:
stmfd sp!, {r0-r2, lr} @ Register retten
ldr r2, =USART0_BASE
1:
ldr r1, [r2, #US_CSR]
tst r1, #US_TXRDY @ ist Transmitter frei
beq 1b
str r0, [r2,#US_THR]
ldmfd sp!, {r0-r2, pc} @ R�cksprung
@ Funktion
.text
.align 2
.global getchar
.type getchar,function
getchar:
stmfd sp!, {r1, r2, lr} @ Register retten
ldr r2, =USART0_BASE
1:
ldr r1, [r2, #US_CSR]
ands r1, r1, #US_RXRDY
beq 1b
ldr r0, [r2, #US_RHR]
ldmfd sp!, {r1, r2, pc} @ R�cksprung
.end
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