| ??? 04/07/09 16:17 Read: times |
#164463 - Use XBYTE macro Responding to: ???'s previous message |
Gopal Amlekar said:
Hello all,
I have an 8051 based circuit, in which an 8255 is connected as memory mapped device. I have not been able to figure out the code to control this IC in C using SDCC. For e.g. to set all 8255 ports in output mode, I need to write 0x80 in the control word register of 8255. In assembly, I can do it with the following code: CONTROL_ADDR_8255 equ 280BH ; This is address of 8255 control word mov A, #80H ;8255 control word to set all ports as O/P, mode 0 mov DPTR, #CONTROL_ADDR_8255 ;Load 8255 address (Control word reg.) in DPTR movx @DPTR, A ;Send control word to 8255 I need some hints on how to do it in C using SDCC compiler? Thanks in advance to all. Regards, #define XBYTE ((unsigned char volatile xdata *) 0) ... #define pio_ctl XBYTE(0x280B) ... pio_ctl = 123; ... variable = pio_ctl; ... The pre-processor is your friend. David. // you may be happier with a function like macro: #define XBYTE(ads) ((unsigned char volatile xdata *) 0)(ads) |
| Topic | Author | Date |
| How to access memory mapped 8255 with SDCC? | 01/01/70 00:00 | |
| also asked here: | 01/01/70 00:00 | |
| 8255 with SDCC | 01/01/70 00:00 | |
| Wrong question? | 01/01/70 00:00 | |
| It's C | 01/01/70 00:00 | |
| not on the 8051 | 01/01/70 00:00 | |
| Oh yes it is! | 01/01/70 00:00 | |
| Use XBYTE macro | 01/01/70 00:00 | |
| Isn't there a problem with that? | 01/01/70 00:00 | |
| Oops. I used a wrong example | 01/01/70 00:00 | |
| Portability | 01/01/70 00:00 | |
| like this... | 01/01/70 00:00 | |
| How about a macro in ASM, callable from 'C'? | 01/01/70 00:00 | |
| This is HOW I will Prefer | 01/01/70 00:00 | |
| LST output of my previously posted code | 01/01/70 00:00 | |
| Try the comparison | 01/01/70 00:00 | |
| Unnecessarily complicated! | 01/01/70 00:00 | |
| NOT UNNECESSARILY | 01/01/70 00:00 | |
| You are mistaken | 01/01/70 00:00 | |
| Array or pointer similar | 01/01/70 00:00 | |
| That should not be necessary | 01/01/70 00:00 | |
| SFRX(...,. ..) worked | 01/01/70 00:00 | |
| SFRX - presumably, that's an SDCC extension? | 01/01/70 00:00 | |
| Found it! | 01/01/70 00:00 | |
RE: Found it! | 01/01/70 00:00 |