| ??? 08/22/05 16:48 Read: times |
#99841 - Errata Responding to: ???'s previous message |
Jan Waclawek said:
The parts list and schematics lists a 3-legged reset of Panasonic, MN13811. According to the datasheet, that is an open-drain, active low reset (see page 7) - hence, not suitable for common '51s. The active high TO-92 reset part is MN13812, however, it is push-pull. I know why this happened: digikey lists them in this - erratic - way.
Comments? My initial comment would be that we have the first errata for the 8052.com SBC. :( You are right about the reason for the error and Digikey's description. The datasheet, in my opinion, does not help make things much clearer either. Doing some further Googling on the MN13811 and 8051 designs I find that they do, in fact, invert the output of the MN13811 signal which is consistent with what you are saying, Jan. The trick all along was finding an active high, open-drain reset supervisor with a through-hole package. I thought I had a winner with the MN13811 but obviously I erred on that. The good news, if there is any, is that the AT89S8253 that the SBC was designed around has its own power-on reset so for normal in-house operation (for which the SBC was designed), the JP5 connector can be totally omitted thus disabling both the MN13811 as well as the R-C network. The SBC wasn't designed to be used "out of the box" in a commercial application, but if it were so used, the middle pin of JP5 could be connected to an appropriate reset signal generator. Additionally, the Dallas DS89C420 (for which the SBC was also designed) has its own internal power-failure capabilities such that no external voltage supervisor is required in that case. In fact, the design is such that it is recommended that JP5 be left completely open with the DS89C420 for that reason. I'll have to continue looking for a good through-hole reset option for future revisions to the board. 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 |