| ??? 10/21/07 00:02 Modified: 10/21/07 01:43 Read: times |
#145961 - I\'m debating this 8052 circuit... |
I have looked at this URL:
http://pjrc.com/tech/8051/board5/schematic.html and I noticed that there could be a data fight. Why? because the designer seemed to connect an address pin of the 8052 to the R/W pin of the HD47780 compatible LCD, and (s)he decided to tie RD, WR, and PSEN of the 8052 together through AND gates to produce one output and connected that output to the LCD enable through a NOR gate. The other end of the NOR gate is connected to an address decoder. My issue is that if the address pin that controls R/W is set to Read, and the enable is active, and the micro wants to write data, then I can see adata clash going on since the micro AND the LCD are outputting data at the same time, and on the same data lines. I think that the way (s)he designed the circuit is done in a bad way. What do you guys think about the circuit? EDIT: I just looked at the 8052 SBC posted at this site after posting the above message, and it seems that its RW pin on the LCD is directly connected to an address line of the micro. |
| Topic | Author | Date |
| I\'m debating this 8052 circuit... | 01/01/70 00:00 | |
| Do you understand why that was done? | 01/01/70 00:00 | |
| I understand, but my debate is not solved. | 01/01/70 00:00 | |
| Avoid the situation! | 01/01/70 00:00 | |
| It should be ... | 01/01/70 00:00 | |
| ... | 01/01/70 00:00 | |
| startup.a51 will do just that unless modified | 01/01/70 00:00 | |
| What's a "startup.a51" | 01/01/70 00:00 | |
| C startup | 01/01/70 00:00 | |
| and if I use my own code... | 01/01/70 00:00 | |
| If you're smart enough to do that ... | 01/01/70 00:00 | |
| MMIO | 01/01/70 00:00 | |
| yes, at osc/12 it's 1 MHz ... but ... | 01/01/70 00:00 | |
| ... | 01/01/70 00:00 | |
| that's crazy | 01/01/70 00:00 | |
| Why worry? | 01/01/70 00:00 | |
| polls? | 01/01/70 00:00 | |
| If you want it to be high-speed, you won't use LCD | 01/01/70 00:00 | |
| experiment with the obvious | 01/01/70 00:00 | |
| Complexity | 01/01/70 00:00 | |
| I think! | 01/01/70 00:00 | |
| If only that were true ... | 01/01/70 00:00 | |
| Think? | 01/01/70 00:00 | |
| ok | 01/01/70 00:00 | |
| Not a matter of guessing.. | 01/01/70 00:00 | |
careful now! | 01/01/70 00:00 | |
| ASM | 01/01/70 00:00 |