| ??? 09/15/05 13:05 Read: times |
#101124 - only four bits Responding to: ???'s previous message |
hi,
Erik Malund said:
U8 P1_shadow
to write ;; modify the bits as needed in P1_shadow mov P1,P1_shadow Well, but then this MOV instruction modifyes all 8 bits of P1 while we need to write only low nibble. Indeed if we use P1_shadow as additional byte which keeps all bits to be wrote to port1 then this is correct. My idea was: MOV A,P1 ; load current state of bits 0...3 XRL A,pin_value ; mask bits which will not be changed ANL A,#0x0F ; mask high nibble XRL P1,A ; change not masked bits The only one trouble may be is that during MOV A,P1 it reads not latch but pins` states and if they are overloaded by any reason then this piece of code fails (reads 0 instead 1). Regards, Oleg |
| Topic | Author | Date |
| Week puzzle IV | 01/01/70 00:00 | |
| In my opinion | 01/01/70 00:00 | |
| no | 01/01/70 00:00 | |
| Bufff!! then TRB | 01/01/70 00:00 | |
| Me and my shadow, walking down the aven | 01/01/70 00:00 | |
| You & your shadow | 01/01/70 00:00 | |
| http://www.coleporter.org/ | 01/01/70 00:00 | |
| it's a hint | 01/01/70 00:00 | |
| Well | 01/01/70 00:00 | |
| you got it | 01/01/70 00:00 | |
| Just OR with ones | 01/01/70 00:00 | |
| how? | 01/01/70 00:00 | |
| a simple solution: | 01/01/70 00:00 | |
| not atomic | 01/01/70 00:00 | |
atomic not possible in general ! | 01/01/70 00:00 | |
| My solution! | 01/01/70 00:00 | |
| Wrong | 01/01/70 00:00 | |
| not atomic | 01/01/70 00:00 | |
| Ok, here is the shadow | 01/01/70 00:00 | |
| only four bits | 01/01/70 00:00 | |
| 2 Hints! | 01/01/70 00:00 | |
| Oh boy, do you need some bible time | 01/01/70 00:00 | |
| re: 2 Hints! | 01/01/70 00:00 |