??? 10/25/10 08:38 Read: times |
#179320 - Use correct capacitor values. Responding to: ???'s previous message |
Tejas H S said:
circuit:
http://ubuntuone.com/p/Lzy/ (Is there an free software using which such circuits can be drawn, as drawing these things using paint like programs is very laborious.) Your schematic shows 22nF (22000pF) capacitors in the XTAL circuit. Even if you have not got schematic software, it is essential that you add a note to describe the error. I have never used a P89V51xxx chip. From my FLASHMAGIC docs, it seems to just use RST to enter bootloader. It is your job to read your data sheets. I have used a P89C51RD2. This uses /PSEN and RST to enter the bootloader. Quite honestly, you should download the data sheet, app notes, etc. Then implement any schematics precisely. Using components that are 1000X the recommended values is unwise. By all means ask about how to calculate values. You will probably be given 'Rule of Thumb' methods. e.g. use 22pF for XTAL, 10nF for decoupling, 100uF for reservoir ... Do not be proud. Copy working designs. Ask... In electronics, these 'Rule of Thumb' values will probably still work at 10X or even 1/10. You can always calculate them properly with the help of a cigarette packet. Incidentally, your original AT89S52 chip can be programmed by many different pieces of software. However you MUST construct the RS232 i/f or LPT i/f exactly to the recommendations. Cutting corners is guaranteed to give you unreliability and often failure. David. |