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Asim Khan's Programmer circuit - XTAL question

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Somphorn

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asimkhan programmer

Hi! I refer to Asim Khan's programmer circuit.

hteeteep://chaokhun.kmitl.ac.th/~kswichit/IspPgm30a/ISP-Pgm30a.html

I wanted to built one. The circuit above connect the 4MHz crystal without using capacitors. In the Atmel datasheet all circuit shown requires that capacitors are to be connected too (33pF typical). So my question is, should I add the capacitors to the said circuit that I'm about to build?
 

ark5230

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xtal in a circuit

Somphorn said:
. In the Atmel datasheet all circuit shown requires that capacitors are to be connected too (33pF typical). So my question is, should I add the capacitors to the said circuit that I'm about to build?

When Atmel requires those two 33 pf caps, what is the point in avoiding those? At times, stray capacitance in the circuit does the job. However no wise user of micro controller would like to tack such poor chances !!
 

    Somphorn

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pranam77

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asim khan isp programmer with circuit

Yes...those capacitors are required for better performance of the xtal. You may use it. Cheers
 

    Somphorn

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Somphorn

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asim khan,microcontroller

I wanted to follow the circuit diagram 100% when constructing it later. But Atmel datasheet suggested differently (as far as the xtal and capacitor is concerned). I wonder whether the original circuit author forgot about those capacitors or intentionally left it like that. If it was intentional then is it because he depended on the stray capacitance like you mentioned.

Anyway, thank for the input. I figured that I will build one without those capacitors and see if it works. Those capacitors can alway be soldered later on if need be.
 

mvs sarma

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asim khan programmer

Somphorn said:
Hi! I refer to Asim Khan's programmer circuit.

hteeteep://chaokhun.kmitl.ac.th/~kswichit/IspPgm30a/ISP-Pgm30a.html

I wanted to built one. The circuit above connect the 4MHz crystal without using capacitors. In the Atmel datasheet all circuit shown requires that capacitors are to be connected too (33pF typical). So my question is, should I add the capacitors to the said circuit that I'm about to build?
Figure2 of the said link shows a Ceramic resonator (2 pin ) and NOT a crystal, please check!!
Later on, some of the others indicated below have adopted crystal and they have the said capacitors.
 

    Somphorn

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ark5230

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Instead of SPI programmer of Figure 2, bette go for ISP programmer of Figure 1. It is simple easy and fully tested and reported a good success record.
Raoof
 

Somphorn

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I've never heard of ceramic resonator before. Checked wikipedia and found out just now. Thanks mvs sarma. Luckily haven't ordered anything from farnell yet. Again, thanks.
 

bobcat1

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Hi

Some microcontroller have build in capacitor for the xtal oscillator (MSP430F4xx for instance )

If the data sheet dose not implay that the micro have build in caps for the oscillator - allways add one because some hardware design might be misteak drawn

All the best
Bobi
microcontroller specialist
 

    Somphorn

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