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flaneth
firmware
ser62500_asm.S
BBM play: add serial MCUF output 115200 8N1
Stefan Schuermans
commited
2dde65d
at 2012-05-06 20:04:32
ser62500_asm.S
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; flaneth - flash and ethernet ; Copyright (C) 2007-2012 Stefan Schuermans <stefan@schuermans.info> ; Copyleft: GNU public license V2 - http://www.gnu.org/copyleft/gpl.html ; a BlinkenArea project - http://www.blinkenarea.org/ */ #include <avr/io.h> .section .text ; output 0 = PC0 ; output a data item with 62500 baud in 9N2 protocol ; extern void Ser62500Out9N2( unsigned short item ); .global Ser62500Out9N2 .func Ser62500Out9N2 Ser62500Out9N2: push R16 ; parameters: R25:R24=value cli ldi R16,0xFF ; PORTC := output sts DDRC,R16 ldi R16,0x00 ; start bit sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 0 sbrc R24,0 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 1 sbrc R24,1 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 2 sbrc R24,2 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 3 sbrc R24,3 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 4 sbrc R24,4 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 5 sbrc R24,5 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 6 sbrc R24,6 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 7 sbrc R24,7 ldi R16,0xFF sts PORTC,R16 rcall wait251 ldi R16,0x00 ; bit 8 sbrc R25,0 ldi R16,0xFF sts PORTC,R16 rcall wait253 ldi R16,0xFF ; 2 stop bits sts PORTC,R16 rcall wait256 rcall wait256 sei pop R16 ret .endfunc ; wait 256/253/251 cycles (including rcall and ret) wait256: nop ; 3 cycles nop nop wait253: nop ; 2 cycles nop wait251: ldi R16, 81 ; 1 cycle, N := 81 wait_loop: dec R16 ; N cycles brne wait_loop ; 2N-1 cycles nop ; 1 cycle ret ; 7 cycles (including rcall)
