Question about parts in ISP programmer

[zhi_yi]

hi there, please help me, can i use C9012 for the T1? in the schematic, it must be BC557, can i replace it with C9012?? and the 4MHz crystal, may i replace it with 12MHz crystal??

thank you

 

[IanP]

Re: ISP Programmer

BC557 can be easily replaced with any general pupose PNP transistor .. however, you can't replace 4MHz crystal ..
Regards,
IanP

 

[zhi_yi]

Re: ISP Programmer

okay, thank you

- why the BC557 can replaced with any general purpose pnp? is it mean that all of the general purposed pnp can be replaced with any other general purpose pnp and also for npn?

- what is the function of the bc557 in the schematic?

- is it the 74541 is buffer ic? what is the function of the buffer there?

- what is the function the crystal there? why should i give the clock to the µC when i want to burn the µC?

- why should i use 4MHz? why i can't replace it with the 12MHz?

thank you very much

 

[IanP]

Re: ISP Programmer

In many applications certain parameters of transistor are not important, for example, if current rating (Ic) of a transistor is 100mA or 200mA, and your application requires 10mA, or if its voltage rating (Vce) is 30V or 50V and you work with only 5V, then you choose whichever you have or whichever is available ..

In this circuit BC557 operates as a switch which switches power (+5V) to the programmed IC .. so nothing special is required, and therefore any general purpose PNP transistor is suitable ..

The buffer IC is used purely for protection of PCs parallel port .. anythig what can happen after buffer will not damage port drivers ..

4MHz crystal clocks the microprocessor .. In serial transmission timing/synchronization is very important, so if you change the frequency most likely you will not be able to program/burn your microcontroller ..

Regards,
IanP

 

[digitalheart]

Re: ISP Programmer

okay, thank you

- why the BC557 can replaced with any general purpose pnp? is it mean that all of the general purposed pnp can be replaced with any other general purpose pnp and also for npn?

- what is the function of the bc557 in the schematic?

- is it the 74541 is buffer ic? what is the function of the buffer there?

- what is the function the crystal there? why should i give the clock to the µC when i want to burn the µC?

- why should i use 4MHz? why i can't replace it with the 12MHz?

thank you very much

- When you use a transistor , you must care of characteristics of that transistor. Like max current, max voltage, max frequency and more! So, If you want to replace it with another, you must choice a transistor which has similar characteristics or better! But your BC557 in shematic act like a switch with very small current and low frequency so you can replace it with any PNP transitor which you have!
- 74541 is a Inverting Octal Tri-state Buffer. Data has to be controlled when computer write it to Flash. Control signal is supply to G1, G2 pins.
- Function of Crystal? Oh! To creat a clock pulse! Coming data is serial, but when it is written to Flash, it's parallel. So u need a clock to do that converting.OK?
- Why should you use 4MHz! It depend on frequency operation of Flash! I think so!
That is not full answer but you can consult it!

 

[Asterik]

ISP Programmer

I think you can replace 4MHz crystal with 12MHz crystal. The function of 4MHz crystal is generate the frequency of the clock pulse, therefore if you replace 4MHz crystal with 12MHz crystal, you will have a higher clock pulse.
I think so!

 

[enas]

ISP Programmer

i think u can replace 4MHz with 12Mhz. in my experience, i usually don't take care about the crystal frequency of the programmed microcontroller and everything work fine. I think in ISP programmer, the clock is controlled by the master/programmer(PC). u should take care about the crystal if there is some special purpose /function of the micros , i.e: serial commnuication in 89s51.

BTW, is this the same as Zhi_yi in teknik elektro UGM forum?greating from me!!

 

[Slayerza]

Re: ISP Programmer

Changing the Xtal from 4 to 12Megs can cause eratic behavior. If you don't plan on rewriting the code that operates this circuit rather don't change the Xtal

Cheers
Slayer

 

[zhi_yi]

Re: ISP Programmer

okay.. thank you very much..

i've try to design the circuit with a breadboard, but when i connect the Vcc and the Ground to the supply.. i see the LED can't light brightly.. what is the problem.. ?? (i am not yet connect the output from the parallel port to the circuit..)

quote:
Changing the Xtal from 4 to 12Megs can cause eratic behavior. If you don't plan on rewriting the code that operates this circuit rather don't change the Xtal
=>what is the meaning with eratic behavior??

okay.. i will try to change it with 12MHz and will tell you soon if it can works properly..

right, enas.. i am the same as zhi_yi in elektronika forum of UGM.. so.. you must be in indonesia too.. are you study in UGM?? may i send a private message to you?


thank you very much

zhi yi

 

[enas]

ISP Programmer

yeah, im indonesian, from electrical engineering of UGM. what is erratic behaviour? may be if the program of micro need running in 4Mhz, you shouldn't change the Xtal. but generally, if the purpose of circuit is only for programmer, u can use another Xtal. The point is the frequency is <24MHz if u use atmel 89s51

btw, OK lah, u can send private message to me

 

[ELKRISHAN]

Re: ISP Programmer

hi there, please help me, can i use C9012 for the T1? in the schematic, it must be BC557, can i replace it with C9012?? and the 4MHz crystal, may i replace it with 12MHz crystal??

thank you

can this programmer circuit also work for p89v51rd2fn microcontroller

Added after 2 minutes:

hi there, please help me, can i use C9012 for the T1? in the schematic, it must be BC557, can i replace it with C9012?? and the 4MHz crystal, may i replace it with 12MHz crystal??

thank you

can the circuit given also work for the p9v51rd2fn microcontroller , pls help i want to make a programmer circuit for p89v51rd2fn microcontroller
thanks in advance