8-bit Microcontrollers中的主题 Re: Entering Run Mode in QG8?

Entering Run Mode in QG8?

admin — Sat, 15 Dec 2007 23:48:06 GMT

Hi guys,
I was wondering if anyone know of an easiest way to enter the run mode upon Power-on reset (POR)? It seems that I would need a timer switch debounce circuit to keep the BKGD/MS pin high when power on and then debounce the switch in order to make use of the pin for output.

Would be greatly appreciated if someone put me on the right track.

Thanks!

Re: Entering Run Mode in QG8?

peg — Sun, 16 Dec 2007 06:05:31 GMT

Hello and welcome, Learner,

You just need to make sure nothing pulls this line low right at power up. If you are using this pin for an output, you don't really need a timer as the code will not change the mode into output until the device is already in run mode.
So if you are going to put some circuitry on this pin, like a simple base resistor and NPN transistor this will probably cause (or possibly cause) entry into background mode. In this case you will need some additional circuitry in between like a buffer gate or a PNP transistor that then drives the NPN.
You don't need to actively drive this pin high, just don't bias it low!

Re: Entering Run Mode in QG8?

admin — Sun, 16 Dec 2007 23:56:56 GMT

Hi Peg,
Thank you so much for your clarification, am greatly in debt to you. I am going to be using the pin to control the Latch Enable pin so I think it should work ok not grounding the BKGD/MS pin except after POR the latch will be temporarily selected but there isn't any data on the ports, will have to wire it up and see how it turns out.

Thanks again!