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zxcm210 reset 8051 help

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Full Member level 3
Sep 15, 2005
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i use at89s52 but have some trouble /maybe reset/ can some tell me is normal to wire direct RST pin on ZXCM to MCU or.... before i allways use capacitor and resistor but now i wann put some reset chip

tell me is normal to wire direct RST pin on ZXCM to MCU

Using a multimeter (or, better, oscilloscope), what is on the RESET pin of '51 (during powerup and after powerup)?


during programing is 1.4V after that is 0 , yesterday i chnge the reset chip with capa. and res. and all work perfekt but i wann use some chip for that

Can you please post (relevant portions of) the schematics?

What happens when you power up the circuit, is the reset always at zero, or does it "jump" a little bit up, for a while? How did you measure it?

Can you try to get (borrow) an oscilloscope, or go somewhere (school, a friendly company) where you can use one? It really helps in situations such as these...


i spoke with my friend and he told me to put resistor between reset chip /PIN reset/ and the reser pin of MCU :))) i think it will work i will try and after that i will post the result
thanks for helping

regards SYRAX

I see no reason why a series resistor would help in case of AT89S52. There are '51 derivatives where the RESET pin is bidirectional (i.e. in case of watchdog event or brownout the mcu pulls up actively the RESET pin from "inside" - e.g. DS89C4x0), where a series resistor would eliminate possible collision - but this is NOT the case of AT89Sxx. You might still have collisitons with your programming "gadget", for which I know nothing, as you posted nothing, so I can't give any help in this regard.

Is there any problem with posting the (relevant part of) schematics (including the ISP circuit if it's permanently connected)? And the result of measurements I asked you for? It's 1 minute work to measure and maybe 5 more to report here... Otherwise, I can't quite see why did you post your original question here... Of course, it's your choice.


it's not easy becouse i am a furniture designer :))) and make electronics after work /when i have a time/ the programer is ATMEGA MCU i haven't the circuit /mt friend make this programmer the targer is simple at89s52 with 5- transistors noting special

I don't think you need a resistor between the output of a supervisory IC such as the ZXCM210 and the RST pin of the AT89S52 ..
What you may need though, and that was indicated by WEK, is a 2-way jumper link between these two pins ..
The role of this jumper is this: when you want to in-circuit program the 89S52 just remove the jumper and your programmer may take control over the RST pin, for normal operation put the jumper back and now the ZXCM210 will reset the microcontroller when appropriate ..
That's it ..


i will try that, but i don't wanna put jumprers in the circuit i will try both variants with resistor and with jumper

thanks for helping :)

now all if fine i put 3.3K between RESET ping and RESET CHIP and all work perfect

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