| ??? 08/01/05 13:28 Read: times |
#98588 - Then take the right parts! Responding to: ???'s previous message |
Zeis said:
I actually use an HC buffer and not an VHC (I cannot find a 74VHC244 buffer in Greece so I use an 74HC244) is this a problem? Of course, is this a problem! Why do you think that D1 is used in the circuit?? 74VHC244 does not provide protection diodes from input to Vcc, while 74HC244 does. In order to isolate the supply coming from printer port from Vcc of target (micro to be programmed), D1 and 74VHC244 is needed. Only by this you can pull down Vcc of target to zero volt (when switching-off Vcc, of course), while the cable is still connected to printer board. Have a look at my link I gave you in the former post, to understand why this is so important and how the 'cable' should be modified to improve performance. Kai |
| Topic | Author | Date |
| AT89S8253 and ISP CABLE | 01/01/70 00:00 | |
| Search here | 01/01/70 00:00 | |
| typo? | 01/01/70 00:00 | |
| Yep. | 01/01/70 00:00 | |
| Try this | 01/01/70 00:00 | |
| Built by your own? | 01/01/70 00:00 | |
| Building it | 01/01/70 00:00 | |
| see this | 01/01/70 00:00 | |
| pcb | 01/01/70 00:00 | |
| i'm sorry .... | 01/01/70 00:00 | |
| Why? | 01/01/70 00:00 | |
| you will see.......... | 01/01/70 00:00 | |
| Then take the right parts! | 01/01/70 00:00 | |
| Problem solved | 01/01/70 00:00 | |
| What magazine | 01/01/70 00:00 | |
| which issue of Elektor | 01/01/70 00:00 | |
| Solution | 01/01/70 00:00 | |
| Alternative site for software | 01/01/70 00:00 | |
| a Thing you have to do is...... | 01/01/70 00:00 | |
| Download failed three times. | 01/01/70 00:00 | |
| Use alternate Charles Bannister gave | 01/01/70 00:00 | |
| Download fm your site was my mistake | 01/01/70 00:00 | |
| Or the one I posted | 01/01/70 00:00 | |
Latest version of ATMELISP from Ulrich | 01/01/70 00:00 |