ST10 PowerUp Problem with my ST10F168 Hardware

st10f168 hardware schematic programer

Hi,

I have a big PowerUp problem with my ST10F168 Hardware.
I have designed a board with a ST10F168 by my self. It works with a 16Bit Non-Multiplexed Bus. When the Boards get power, some of them needs extreme long to start the program from the external flash memory.
What I not understand is, all the boards have the same Hardware on it. They running with the same programm, but why need them not the same time to start the program? Where the problem?
When the controller have started after power up, they all works fine! I can reset them and the controller starts in the same moment as i release the reset button. I don't know where the power up problem is.
I have checked the power on the board with a oscilloscope, but it came up normal!
Some controller need up to 5 minutes to start the programm!!

Who can help me!! Phytex

re: ST10 PowerUp Problem

> I have a big PowerUp problem with my ST10F168 Hardware.
> I have designed a board with a ST10F168 by my self. It works with a
> 16Bit Non-Multiplexed Bus. When the Boards get power, some of them
> needs extreme long to start the program from the external flash
> memory. What I not understand is, all the boards have the same
> Hardware on it. They running with the same programm, but why need
> them not the same time to start the program? Where the problem?
> When the controller have started after power up, they all works fine! I
> can reset them and the controller starts in the same moment as i
> release the reset button. I don't know where the power up problem is.
> I have checked the power on the board with a oscilloscope, but it came
> up normal!
> Some controller need up to 5 minutes to start the programm!!

Without seeing a schematic it's hard to say what the problem might be. But by the sounds of it, I'd guess that the processor reset line is floating. This would give long startup times, for different boards. You have at least a reset button on the reset line, do you also have an RC combination for power up, or are you using a micro-processor supervisor chip?
Other things that could cause such a problem are the nNMI pin floating or the nEA pin floating (it should be pulled low for an external bus configuration.)


alpha

external Config.

Hi,

at first, THX for help.

My /NMI is pulled high with a 10k resistor. In the datasheet of the ST10 St says that the NMI have to pulled high and not low when the pin is not used.
The /EA is pulled low directly to GND so that the Controller boots from the external bus. I have checked the reset line, it is not floating!
I don't know where the problem is!

Phytex

Re: ST10 PowerUp Problem

Are you sure the reset pin is being held low for a small time (200ms) after the st10 has powered up !! If not then the micro may behave erratically