| ??? 03/30/10 09:38 Read: times |
#174620 - signals Responding to: ???'s previous message |
Don't rush to make a revision to your PCB until you get the first working, even at the cost of cutting traces and rewiring them to a "bird's nest".
You should first make sure your signals are clean enough - use 1k pullups on all signals. The "traditional" '51's bidirectional IO has poor pullup capability when it comes to slightly longer buses/wires loaded by more ICs. We don't know what is the frequency you run your '51 at, nor the mode (x2 or not); note that you might be violating the timing of the display especially when reading - insert a NOP or two between setting E high and reading in the data. Then make some provisions to be able to observe the behaviour of the program, how far does it get. For example, I'd be willing to bet it does not get beyond the very first busy check, prove me I am wrong. Set a "light up a LED" at selected checkpoints. Also you might single-step through your code, if you have some sort of emulator or monitor. Or, simply, call a "wait until a button is pressed then released (debounced of course)" routine from key points of the program. You might then observe the levels of each line by simple tools (voltmeter). JW |
| Topic | Author | Date |
| nothing displayed on graphical lcd using P89V51rd2. | 01/01/70 00:00 | |
| Try to adjust contrast | 01/01/70 00:00 | |
| About The Bus Twist | 01/01/70 00:00 | |
| Start Extremely Simple | 01/01/70 00:00 | |
| But how will i know that data is getting written to the vari | 01/01/70 00:00 | |
| read it | 01/01/70 00:00 | |
| read it !! | 01/01/70 00:00 | |
| RE: registers that may be read/write | 01/01/70 00:00 | |
| Try the text mode | 01/01/70 00:00 | |
| That could be step 2 | 01/01/70 00:00 | |
| no text mode | 01/01/70 00:00 | |
| more on contrast | 01/01/70 00:00 | |
| signals | 01/01/70 00:00 | |
| Success! | 01/01/70 00:00 | |
| work to do | 01/01/70 00:00 | |
| i agree | 01/01/70 00:00 | |
| one more doubt | 01/01/70 00:00 | |
| an easier alternative | 01/01/70 00:00 | |
| Isn't this a question to the mentor? | 01/01/70 00:00 | |
| Need For A Buffer With GLCD | 01/01/70 00:00 | |
| dot line buffer | 01/01/70 00:00 | |
nothing displayed on graphical lcd using P89V51rd2 | 01/01/70 00:00 | |
| Thanks | 01/01/70 00:00 |