Is there a MCU that outputs 0 on all ports upon reset?

[flashking]

Hello mates

Is there a microcontroller that outputs low when it is reseted ?

the atmel 89c51 outputs high on all ports upon reset and that will make some trouble with my circuit

thanks

 

[john blue]

Just invert the output using diode?

 

[nandhu015]

Hello mates

Is there a microcontroller that outputs low when it is reseted ?

the atmel 89c51 outputs high on all ports upon reset and that will make some trouble with my circuit

thanks

AVR, PIC, etc..

 

[flashking]

Just invert the output using diode?

thanks but gates and inverters would increase the complexity and the unreliability of the circuit,however if you know a reliable ic that works under moderate power then please help me

AVR, PIC, etc..

thanks I will try to use one of them

 

[M!k]

Your problem seems to be more that the IOs are configured as input after a reset. For an 8051 the output transistor (open collector)
is open after a reset and you'll see a high because of the internal pull-up resistor.
When using e.g. a PIC there is no internal pull-up resistor. So this input pin (that's what it is after a reset) is floating between high and low.
The only thing you can do is adding an external pull-down resistor to have a defined low-level after reset.

 

[incomplete_jerin]

The only thing you can do is adding an external pull-down resistor to have a defined low-level after reset.

That would be fine.
Regards,
Jerin.

 

[flashking]

Your problem seems to be more that the IOs are configured as input after a reset. For an 8051 the output transistor (open collector)
is open after a reset and you'll see a high because of the internal pull-up resistor.When using e.g. a PIC there is no internal pull-up resistor. So this input pin (that's what it is after a reset) is floating between high and low.The only thing you can do is adding an external pull-down resistor to have a defined low-level after reset.

thanks for the details

but should I use the pull down resistor with the pic only or youe meant that it is good for bith 8051 and pic ? and do you suggest a value ?

 

[M!k]

Using a pull-down with a 89c51 won't work due to the open-collector architecture. Please take a look here: https://www.freewebs.com/maheshwankhede/basic/port.GIF
So this proposal is only useful for PIC or similar. 10k should be OK

 

[123jack]

I'm starting to sound like a salesman - sorry !

Try the mikroElectronica web site - they have a whole book online.
Also I highly recommend their free compiler/IDE.

jack

 

[incomplete_jerin]

Just understand the instructions fro PIC & read the users manual for MPLAB. Do the code oe your own. Post the doubts here. Get it answered & keep ROCKIN!!!!!!!!!!!!!!!!!!!!
Regards,
Jerin. ;-)