| ??? 04/05/07 12:10 Read: times |
#136675 - i knew it Responding to: ???'s previous message |
Although I have no status ports in use, the way I verify that everything works is that I send the code in programming mode, and then watch the CPU go to work. How do you observe that the CPU goes to work doing what you intend? The LCD display shows me everything that goes on, and so does my computer. In fact, I made myself a working server that hyperterminal can connect to. At the moment it doesn't do much, but wait for a key and then display a menu. What I noticed is that in order to successfully program a byte into the eeprom, I had to write a byte to it (bit set low) for 100 or so microseconds, and then I set the bit high, but it must remain high for at least 1/2 a second.
Once again, timing can control alot. Which "bit" is that? the WE pin of the EEPROM is what I refer to. BTW, I suspect you're forming a bad habit here ... "alot" is normally two words ... a lot ... and I'm just pointing it out so you're aware. Thanks. How did you arrive at the conclusion that you have to wait a half second? That seems quite long. Have you consulted the EEPROM datasheet for precise timing constraints? Yes, but I was experimenting again. It seems that if I set WE low quickly (like 100uS) and pull it high for almost 1/2 a second, a write happens. my design does not involve tying PSEN and RD together with an AND gate, because I think the system won't work due to excessive track lengths.
Typical delays for track length are on the order of a nanosecond or two per foot. I knew track length was a factor! Because in this design, I fattened the ALE track (1.2mm width) and shortened it to about an inch. before it was a couple of inches in length and 0.25mm width. |
| Topic | Author | Date |
| My board works! | 01/01/70 00:00 | |
| You may eventually find ... | 01/01/70 00:00 | |
| answer | 01/01/70 00:00 | |
| How'd you do it? | 01/01/70 00:00 | |
| i knew it | 01/01/70 00:00 | |
| Are you sure you aren\'t looking in the wrong place | 01/01/70 00:00 | |
| . | 01/01/70 00:00 | |
| Be sure to adhere to standard syntax | 01/01/70 00:00 | |
| free assembler | 01/01/70 00:00 | |
10 lines of code to transfer a string | 01/01/70 00:00 | |
| Congrats! | 01/01/70 00:00 |