| ??? 11/21/07 02:42 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#147287 - Logical operations Responding to: ???'s previous message |
In your two WRITE operations you move DATA to B and then ORL B with 0F0h but then do nothing with the result. Also, ORL sets bits, it won't clear them. When you ORL with 0F0h the left nibble is set to 1111 and the right nibble is left alone.
ANL with 0F0h will leave the left nibble as is and set the right nibble to 0000. The fifth statement under WRITE_TEXT you are moving the contents of Acc to port 2 with an ANL operation. I don't think you want to do this since ANL will bitwise AND the contents of Acc with whatever is currently on the port from previous operations. Instead of ANL simply use MOV. Also, since you have placed RS and EN on the same port with data you must maintain complete control of the state of EN during your setups so that moving data to the port does not inadvertently toggle EN and throw everything off. You might want to consider using a one byte memory location or register to set up what is needed, then just move the byte to the port. Hal |
| Topic | Author | Date |
| 4 bit LCD trouble | 01/01/70 00:00 | |
| Possible Error | 01/01/70 00:00 | |
| DATA is port EN is pin | 01/01/70 00:00 | |
| Initialization | 01/01/70 00:00 | |
| I think I did initialize correct | 01/01/70 00:00 | |
| Logical operations | 01/01/70 00:00 | |
| Oops, should have been ANL BA | 01/01/70 00:00 | |
| Clobbering your data | 01/01/70 00:00 | |
| topic gone?? | 01/01/70 00:00 | |
| code library | 01/01/70 00:00 | |
| Try LCD Tutorial in tutorials section | 01/01/70 00:00 | |
| Tutorial uses 2 ports | 01/01/70 00:00 | |
| previous comments... | 01/01/70 00:00 | |
| All tested an nailed the problem | 01/01/70 00:00 | |
| yes, timing | 01/01/70 00:00 | |
Some code shortening: | 01/01/70 00:00 |