Home » Archimedes archive » Acorn User » AU 1997-10 A.adf » Extras » Apple][e/PD/PIC/!PICbasic/Extras/Interrupt
Apple][e/PD/PIC/!PICbasic/Extras/Interrupt
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Archimedes archive » Acorn User » AU 1997-10 A.adf » Extras |
| Filename: | Apple][e/PD/PIC/!PICbasic/Extras/Interrupt |
| Read OK: | ✔ |
| File size: | 03A3 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
Interrupts ========== Using interrupts on the PIC If you want to save the status register (recommended), you will need to make use of the SWaPF f,w instruction which doesn't affect the z flag like MOVF f,w does.This is an example of how to start and end to an interrupt service routine.Only two source responses are shown for clarity. .irqhandler MOVWF irqwork SWaPF status,W MOVWF irqstatus .irqtests BTFSC timer0flag \Has timer zero timed out? GOTO timer0irq \This is where the handler is BTFSC deltaBflag \Was it a port B change interrupt? GOTO deltaBirq \This is where the handler is .irqserviced SWaPF irqstatus,W MOVWF status \Restore 'status' SWaPF irqwork,F SWaPF irqwork,W \Restore 'W',being careful not to damage 'status' register RETFIE .timer0irq \Do something GOTO irqserviced .deltaBirq \Do something GOTO irqserviced This should work on the 16C61,16C71,and 16C84,but not on parts with paged registers.
00000000 49 6e 74 65 72 72 75 70 74 73 0a 3d 3d 3d 3d 3d |Interrupts.=====| 00000010 3d 3d 3d 3d 3d 0a 55 73 69 6e 67 20 69 6e 74 65 |=====.Using inte| 00000020 72 72 75 70 74 73 20 6f 6e 20 74 68 65 20 50 49 |rrupts on the PI| 00000030 43 0a 0a 49 66 20 79 6f 75 20 77 61 6e 74 20 74 |C..If you want t| 00000040 6f 20 73 61 76 65 20 74 68 65 20 73 74 61 74 75 |o save the statu| 00000050 73 20 72 65 67 69 73 74 65 72 20 28 72 65 63 6f |s register (reco| 00000060 6d 6d 65 6e 64 65 64 29 2c 20 79 6f 75 20 77 69 |mmended), you wi| 00000070 6c 6c 20 6e 65 65 64 20 74 6f 20 6d 61 6b 65 0a |ll need to make.| 00000080 75 73 65 20 6f 66 20 74 68 65 20 53 57 61 50 46 |use of the SWaPF| 00000090 20 66 2c 77 20 69 6e 73 74 72 75 63 74 69 6f 6e | f,w instruction| 000000a0 20 77 68 69 63 68 20 64 6f 65 73 6e 27 74 20 61 | which doesn't a| 000000b0 66 66 65 63 74 20 74 68 65 20 7a 20 66 6c 61 67 |ffect the z flag| 000000c0 20 6c 69 6b 65 20 4d 4f 56 46 20 66 2c 77 20 0a | like MOVF f,w .| 000000d0 64 6f 65 73 2e 54 68 69 73 20 69 73 20 61 6e 20 |does.This is an | 000000e0 65 78 61 6d 70 6c 65 20 6f 66 20 68 6f 77 20 74 |example of how t| 000000f0 6f 20 73 74 61 72 74 20 61 6e 64 20 65 6e 64 20 |o start and end | 00000100 74 6f 20 61 6e 20 69 6e 74 65 72 72 75 70 74 20 |to an interrupt | 00000110 73 65 72 76 69 63 65 20 0a 72 6f 75 74 69 6e 65 |service .routine| 00000120 2e 4f 6e 6c 79 20 74 77 6f 20 73 6f 75 72 63 65 |.Only two source| 00000130 20 72 65 73 70 6f 6e 73 65 73 20 61 72 65 20 73 | responses are s| 00000140 68 6f 77 6e 20 66 6f 72 20 63 6c 61 72 69 74 79 |hown for clarity| 00000150 2e 0a 0a 2e 69 72 71 68 61 6e 64 6c 65 72 0a 4d |....irqhandler.M| 00000160 4f 56 57 46 20 69 72 71 77 6f 72 6b 0a 53 57 61 |OVWF irqwork.SWa| 00000170 50 46 20 73 74 61 74 75 73 2c 57 0a 4d 4f 56 57 |PF status,W.MOVW| 00000180 46 20 69 72 71 73 74 61 74 75 73 0a 0a 2e 69 72 |F irqstatus...ir| 00000190 71 74 65 73 74 73 0a 42 54 46 53 43 20 74 69 6d |qtests.BTFSC tim| 000001a0 65 72 30 66 6c 61 67 20 20 5c 48 61 73 20 74 69 |er0flag \Has ti| 000001b0 6d 65 72 20 7a 65 72 6f 20 74 69 6d 65 64 20 6f |mer zero timed o| 000001c0 75 74 3f 0a 47 4f 54 4f 20 74 69 6d 65 72 30 69 |ut?.GOTO timer0i| 000001d0 72 71 20 20 5c 54 68 69 73 20 69 73 20 77 68 65 |rq \This is whe| 000001e0 72 65 20 74 68 65 20 68 61 6e 64 6c 65 72 20 69 |re the handler i| 000001f0 73 0a 42 54 46 53 43 20 64 65 6c 74 61 42 66 6c |s.BTFSC deltaBfl| 00000200 61 67 20 20 5c 57 61 73 20 69 74 20 61 20 70 6f |ag \Was it a po| 00000210 72 74 20 42 20 63 68 61 6e 67 65 20 69 6e 74 65 |rt B change inte| 00000220 72 72 75 70 74 3f 0a 47 4f 54 4f 20 64 65 6c 74 |rrupt?.GOTO delt| 00000230 61 42 69 72 71 20 20 5c 54 68 69 73 20 69 73 20 |aBirq \This is | 00000240 77 68 65 72 65 20 74 68 65 20 68 61 6e 64 6c 65 |where the handle| 00000250 72 20 69 73 0a 0a 2e 69 72 71 73 65 72 76 69 63 |r is...irqservic| 00000260 65 64 0a 53 57 61 50 46 20 69 72 71 73 74 61 74 |ed.SWaPF irqstat| 00000270 75 73 2c 57 0a 4d 4f 56 57 46 20 73 74 61 74 75 |us,W.MOVWF statu| 00000280 73 20 20 5c 52 65 73 74 6f 72 65 20 27 73 74 61 |s \Restore 'sta| 00000290 74 75 73 27 0a 53 57 61 50 46 20 69 72 71 77 6f |tus'.SWaPF irqwo| 000002a0 72 6b 2c 46 0a 53 57 61 50 46 20 69 72 71 77 6f |rk,F.SWaPF irqwo| 000002b0 72 6b 2c 57 20 20 5c 52 65 73 74 6f 72 65 20 27 |rk,W \Restore '| 000002c0 57 27 2c 62 65 69 6e 67 20 63 61 72 65 66 75 6c |W',being careful| 000002d0 20 6e 6f 74 20 74 6f 20 64 61 6d 61 67 65 20 27 | not to damage '| 000002e0 73 74 61 74 75 73 27 20 72 65 67 69 73 74 65 72 |status' register| 000002f0 0a 52 45 54 46 49 45 0a 0a 2e 74 69 6d 65 72 30 |.RETFIE...timer0| 00000300 69 72 71 0a 5c 44 6f 20 73 6f 6d 65 74 68 69 6e |irq.\Do somethin| 00000310 67 0a 47 4f 54 4f 20 69 72 71 73 65 72 76 69 63 |g.GOTO irqservic| 00000320 65 64 0a 0a 2e 64 65 6c 74 61 42 69 72 71 0a 5c |ed...deltaBirq.\| 00000330 44 6f 20 73 6f 6d 65 74 68 69 6e 67 0a 47 4f 54 |Do something.GOT| 00000340 4f 20 69 72 71 73 65 72 76 69 63 65 64 0a 0a 54 |O irqserviced..T| 00000350 68 69 73 20 73 68 6f 75 6c 64 20 77 6f 72 6b 20 |his should work | 00000360 6f 6e 20 74 68 65 20 31 36 43 36 31 2c 31 36 43 |on the 16C61,16C| 00000370 37 31 2c 61 6e 64 20 31 36 43 38 34 2c 62 75 74 |71,and 16C84,but| 00000380 20 6e 6f 74 20 6f 6e 20 70 61 72 74 73 20 77 69 | not on parts wi| 00000390 74 68 20 70 61 67 65 64 0a 72 65 67 69 73 74 65 |th paged.registe| 000003a0 72 73 2e |rs.| 000003a3
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