| ??? 08/24/05 17:28 Read: times |
#100019 - No explanation Responding to: ???'s previous message |
Jon Ledbetter said:
I put in a blank AT89C52 in and it worked, so I tried my extra '8253 and it started like it should. I probably toasted the other one when I tried the '8252 algorithm on my programmer. Glad that question is resolved. I double checked the '125 again, as long as it is in the monitor will only start if the jumper is in the yes position. If the jumper is removed or in the no position there is no responce. Like I said before, I just figured it has something to do with the '126 not being there. This one still bothers me. The lack of the '126 should have no adverse effect other than not being able to do AT89S8253 ISP. I just removed the HC126 from my SBC and left the '125 in with the jumper in the "no" position and running from EPROM and it worked fine. The '125/JP4 section of the circuit is very straight-forward. If in the "No" position, the gate inputs to the '125 are "high" which puts the outputs into high impedance and should have no effect on the microcontroller. You might check continuity on the pins of the '125 and make sure there are no shorts. Particularly, verify that none of the solder points have caused a short involving one or more pins 4, 9, 10, 12 or 13 on the '125 part. You might also check for shorts on one or more of the three pins of JP4 and check the voltage on pins 4, 10, and 13 of the '125 when JP4 is in the "No" position and what the voltage is on those same pins when in the "Yes" position. Regards, Craig Steiner |
| Topic | Author | Date |
| 8052.com SBC | 01/01/70 00:00 | |
| SBC | 01/01/70 00:00 | |
| I'm Interested, but no big hurry | 01/01/70 00:00 | |
| Good point | 01/01/70 00:00 | |
| BTW | 01/01/70 00:00 | |
| I'll update | 01/01/70 00:00 | |
| This is a nice chip when you need pins g | 01/01/70 00:00 | |
| Questioins | 01/01/70 00:00 | |
| elaborations | 01/01/70 00:00 | |
| RD2 programming | 01/01/70 00:00 | |
| Question | 01/01/70 00:00 | |
| RD2 and PSEN | 01/01/70 00:00 | |
| LeDot | 01/01/70 00:00 | |
| solder point | 01/01/70 00:00 | |
| go figure | 01/01/70 00:00 | |
| solder point/LeDot | 01/01/70 00:00 | |
| Jumper/button | 01/01/70 00:00 | |
| datasheet | 01/01/70 00:00 | |
| RD2, /PSEN and the joy of being perfect | 01/01/70 00:00 | |
| I think | 01/01/70 00:00 | |
| Herr Ohm says no | 01/01/70 00:00 | |
| Hands off | 01/01/70 00:00 | |
| no touch | 01/01/70 00:00 | |
| tidbits | 01/01/70 00:00 | |
| AT89S8253 | 01/01/70 00:00 | |
| First hand experiance | 01/01/70 00:00 | |
| RE:Experience | 01/01/70 00:00 | |
| SBC page updated | 01/01/70 00:00 | |
| Required HW for 8052.com Institute of uC | 01/01/70 00:00 | |
| that Erik has voluteered to teach ??? | 01/01/70 00:00 | |
| Retirement | 01/01/70 00:00 | |
| Well | 01/01/70 00:00 | |
| genetically as well | 01/01/70 00:00 | |
| I too... | 01/01/70 00:00 | |
| u51 one possibility | 01/01/70 00:00 | |
| I like part of that | 01/01/70 00:00 | |
| not good | 01/01/70 00:00 | |
| I see your point - did you see mine? | 01/01/70 00:00 | |
| got better | 01/01/70 00:00 | |
| you did not | 01/01/70 00:00 | |
| Are you sure about your .29$ | 01/01/70 00:00 | |
| oops | 01/01/70 00:00 | |
| single nand gate?? | 01/01/70 00:00 | |
| Ok spelling it out | 01/01/70 00:00 | |
| And it supports DS89C4x0! | 01/01/70 00:00 | |
| Nice effort | 01/01/70 00:00 | |
| PCB layouts | 01/01/70 00:00 | |
| not even gerber? | 01/01/70 00:00 | |
| ExpressPCB | 01/01/70 00:00 | |
| Keil was | 01/01/70 00:00 | |
| If needs be | 01/01/70 00:00 | |
| 8052.com SBC available for ordering | 01/01/70 00:00 | |
| Selling like hotcakes? | 01/01/70 00:00 | |
| Not bad | 01/01/70 00:00 | |
| AT89S8253 | 01/01/70 00:00 | |
| Yes | 01/01/70 00:00 | |
| Errata | 01/01/70 00:00 | |
| AT89S8253 ISP | 01/01/70 00:00 | |
| Didn't look very hard | 01/01/70 00:00 | |
| I already tried | 01/01/70 00:00 | |
| 8052.com SBC and 8052Sim | 01/01/70 00:00 | |
| Sort of and yes | 01/01/70 00:00 | |
| Pinnacle52 | 01/01/70 00:00 | |
| Why? | 01/01/70 00:00 | |
| Touche' | 01/01/70 00:00 | |
| Hard to resist | 01/01/70 00:00 | |
| Dress | 01/01/70 00:00 | |
| re classes etc | 01/01/70 00:00 | |
| re classes etc - an example | 01/01/70 00:00 | |
| Question on BOM | 01/01/70 00:00 | |
| Yes | 01/01/70 00:00 | |
| New Items added to 8052.com SBC Page | 01/01/70 00:00 | |
| 74LS573? | 01/01/70 00:00 | |
| Correct | 01/01/70 00:00 | |
| reset | 01/01/70 00:00 | |
| Errata | 01/01/70 00:00 | |
| Mine has arrived . . . | 01/01/70 00:00 | |
| Wow | 01/01/70 00:00 | |
| A minor problem | 01/01/70 00:00 | |
| Caps for MAX232 | 01/01/70 00:00 | |
| Whole point.... | 01/01/70 00:00 | |
| MAX232 Caps | 01/01/70 00:00 | |
| Deflux | 01/01/70 00:00 | |
| Works like a charm! | 01/01/70 00:00 | |
| Never mind, got it figured out | 01/01/70 00:00 | |
| Glad you got it working | 01/01/70 00:00 | |
| SBC-BASIC | 01/01/70 00:00 | |
| See email | 01/01/70 00:00 | |
| yes I will... | 01/01/70 00:00 | |
| Any luck with that yet? | 01/01/70 00:00 | |
| Not yet | 01/01/70 00:00 | |
| Sure! | 01/01/70 00:00 | |
| in that case... | 01/01/70 00:00 | |
| I've got a couple of RD2's | 01/01/70 00:00 | |
| http://www.efton.sk | 01/01/70 00:00 | |
| What about ED2's | 01/01/70 00:00 | |
| yes | 01/01/70 00:00 | |
| Basic 52/RD2 | 01/01/70 00:00 | |
| b52rd2 | 01/01/70 00:00 | |
| it works for me | 01/01/70 00:00 | |
| Real hackers | 01/01/70 00:00 | |
Basic 52 | 01/01/70 00:00 | |
| I got mine today! | 01/01/70 00:00 | |
| Darn the luck | 01/01/70 00:00 | |
| Comments | 01/01/70 00:00 | |
| Our Radio Shack Stinks | 01/01/70 00:00 | |
| An Idea | 01/01/70 00:00 | |
| 125 | 01/01/70 00:00 | |
| RE: '125 and JP4 | 01/01/70 00:00 | |
| Yes position? | 01/01/70 00:00 | |
| Got it - Bad 8253 | 01/01/70 00:00 | |
| No explanation | 01/01/70 00:00 | |
| You were right the first time - my bad | 01/01/70 00:00 | |
| No problem | 01/01/70 00:00 | |
| Memory mapped LCD problems | 01/01/70 00:00 | |
| Hmmm | 01/01/70 00:00 | |
| Building one | 01/01/70 00:00 | |
| Microseconds? | 01/01/70 00:00 | |
| Scale error | 01/01/70 00:00 | |
| Memory-mapped LCD initialization | 01/01/70 00:00 | |
| Thanks, Craig! It works! | 01/01/70 00:00 | |
| SBC - Manual | 01/01/70 00:00 | |
| SBC document | 01/01/70 00:00 |