\n \n<\/p>\n
\r\n\r\n\t_asm\r\n\t\/\/Reset timer for next rollover\r\n\tmovff\tTMR0L,uc_asm_irq_temp\t\t\t\/\/read_current_timer_value (read low byte loads high byte)\r\n\tmovff\tTMR0H,uc_asm_irq_temp1\r\n\tmovlw\t0xbb\r\n\taddwf\tuc_asm_irq_temp,1,0\t\t\t\t\/\/(1 = file register, 0 = access ram)\r\n\tmovlw\t0x3c\r\n\taddwfc\tuc_asm_irq_temp1,1,0\t\t\t\/\/(1 = file register, 0 = access ram)\r\n\tmovff\tuc_asm_irq_temp1,TMR0H\t\t\t\/\/Store new value (high byte first)\r\n\tmovff\tuc_asm_irq_temp,TMR0L\r\n\t_endasm\r\n<\/code><\/pre>\n\nNewer XC Code
\n<\/h5>\n
\nIMPORTANT – MAKE SURE XC8 OPTIMIZATIONS 'ADDRESS QUALIFIERS' IS SET TO 'REQUIRE' \n<\/p>\n
\r\n\r\n\t#asm\r\n\tGLOBAL _uc_asm_irq_temp\r\n\tGLOBAL _uc_asm_irq_temp1\r\n\t\/\/Reset timer for next rollover\r\n\tmovff\tTMR0L,_uc_asm_irq_temp\t\t\t\/\/read_current_timer_value (read low byte loads high byte)\r\n\tmovff\tTMR0H,_uc_asm_irq_temp1\r\n\tmovlw\t0xfb\r\n\taddwf\t_uc_asm_irq_temp,f,c\t\t\t\t\/\/(f = file register, c = common\/access ram)\r\n\tmovlw\t0xd8\r\n\taddwfc\t_uc_asm_irq_temp1,f,c\t\t\t\/\/(f = file register, c = common\/access ram)\r\n\tmovff\t_uc_asm_irq_temp1,TMR0H\t\t\t\/\/Store new value (high byte first)\r\n\tmovff\t_uc_asm_irq_temp,TMR0L\r\n\t#endasm\r\n<\/code><\/pre>\n\nWhat changed:\n<\/p>\n
\n_asm and _endasm change to #asm and #endasm
\nVariables are declared in C without a leading underscore, but to be used in assembler code they must have a leading underscore added and be declared using GLOBAL.\n<\/p>\n
\nPrevious XC Code
\n<\/h5>\n
\nNewer versions of XC8 generate a "error: (876) syntax error" to the use of the below. It turns out ",1,0" on the end of the addwf and addwfc lines are the issue (even though these numeric values are specified for use in device datasheets). \n<\/p>\n
\nThe '1' needs to change to 'f' for file register.\n<\/p>\n
\nThe '0' needs to change to 'c' for common memory \/ access ram (the alternative would be 'b' for bank select register).\n<\/p>\n
\nIMPORTANT – MAKE SURE XC8 OPTIMIZATIONS 'ADDRESS QUALIFIERS' IS SET TO 'REQUIRE' <\/em>\n<\/p>\n\r\n\r\n\t#asm\r\n\tGLOBAL _uc_asm_irq_temp\r\n\tGLOBAL _uc_asm_irq_temp1\r\n\t\/\/Reset timer for next rollover\r\n\tmovff\tTMR0L,_uc_asm_irq_temp\t\t\t\/\/read_current_timer_value (read low byte loads high byte)\r\n\tmovff\tTMR0H,_uc_asm_irq_temp1\r\n\tmovlw\t0xbb\r\n\taddwf\t_uc_asm_irq_temp,1,0\t\t\t\t\/\/(1 = file register, 0 = access ram)\r\n\tmovlw\t0x3c\r\n\taddwfc\t_uc_asm_irq_temp1,1,0\t\t\t\/\/(1 = file register, 0 = access ram)\r\n\tmovff\t_uc_asm_irq_temp1,TMR0H\t\t\t\/\/Store new value (high byte first)\r\n\tmovff\t_uc_asm_irq_temp,TMR0L\r\n\t#endasm\r\n<\/code><\/pre>\n\n \n<\/p>\n
\nFor more information see the "C18 to XC8 C Compiler Migration Guide" as there are some key differences\n<\/p>\n
\nInstruction Arguments
\n<\/h4>\n
\nDestination select bit\n<\/p>\n
\nw = store result in WREG (0)
\nf = store result in file register f (1)\n<\/p>\n
\nRAM access bit\n<\/p>\n
\nc = common \/ access ram (0)
\nb = bank select register (1)\n<\/p>\n
\n <\/p>\n","protected":false},"excerpt":{"rendered":"
Simple example of changes to typical heartbeat timer irq inline assembly Original C18 Code _asm \/\/Reset timer for next rollover movff TMR0L,uc_asm_irq_temp \/\/read_current_timer_value (read low byte loads high byte) movff TMR0H,uc_asm_irq_temp1 movlw 0xbb addwf uc_asm_irq_temp,1,0 \/\/(1 = file register, 0 = access ram) movlw 0x3c addwfc uc_asm_irq_temp1,1,0 \/\/(1 = file register, 0 = access ram) […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[55,56],"tags":[],"class_list":["post-502","post","type-post","status-publish","format-standard","hentry","category-converting-from-c18-projects-to-xc8","category-basic-template-project-changes"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/posts\/502","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/comments?post=502"}],"version-history":[{"count":7,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/posts\/502\/revisions"}],"predecessor-version":[{"id":602,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/posts\/502\/revisions\/602"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/media?parent=502"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/categories?post=502"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/embedded\/wp-json\/wp\/v2\/tags?post=502"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}