A simple circuit - help pls

[Ian T]

Hi Folks,
I need a push button that will drive a single pulse of XTAL-1 each time I
press it and in turn the chip will respond with 8 bits which I
would like to read manually by LEDs. Would I need something like a LS245
data latch to catch the data for the LED's to be stable??
A battery would provide the power for the chip & XTAL.Please keep it as
simple as possible as I'm not schooled in electronics.

thanks in advance.
--
Ian Turnbull
Tel: 07961 931941
Fax: 0870 137 1834

mailto:[email protected]

 

[happyhobit]

Well Ian,

Your explanation needs a bit more. You press a button and the 'chip'
responds with 8 bits? XTAL-1?

Is this chip counting your button presses? Are the 8 bits randomly
generated?



Jay

 

[Ian T]

Thanks for responding. Basically its a microcontroller I found in the local
tip. It appears to be from a Paintball gun.
I'm interested in playing about with it. XTAL-1 is one of the 24Mghz pins
which from the documentation from Atmels site
says advances the location counter. If pins 3,4,5,6 are Low Low High High
when XTAL-1 is pulsed it will respond by spitting out the
contents of on board memory. On Restart the location counter goes to 0 and
each XTAL-1 pulse advances it 1 location.
Now thats the gist of the documentation for the chip-microcontroller and I
want to learn something about electronics and
this has enthused me as a starting point.
Does this help? Or am I talking gibberish?
regards,
Ian T

 

[Ian T]

an 8 bit port on the AT89C4051 microcontroller

question: what chip? will respond with 8 bits

question: what 8 bits? what makes the 8 bits?
which I

 

[Ian T]

Well Jay,
That's why I posted here to get knowlegable people's help, like yours. 27
years experience I can't pick up from a couple of books!!
Thanks for the info but I'd rather have a simple circuit than to have to
read books on both electronics and micrcontrollers.
But, well thanks for the info but a circuit would have been better? That's
what I asked for!

 

[Geoff Hackett]

The chip you mention can work from a pulse on the xtal pin. The circuit you
need is called a monostable timer, NE555 timer IC can be set in this mode,
loads of circuits on the net! the latch you mention is not required as the
port will latch its self. The leds can be connected to ground though a
resistor on each LED.

It is not very likely that the program the CPU is running will output to the
port very often though.

There are a lot of books on the subject of microcontrollers but if you want
a simple start into the subject you could buy a starter kit. These have lots
of doc's with them and although it's not easy, you can get a great deal from
these devices. Consider on a FLASH based device that can be reprogrammed and
with in-system program parts like ATMEL avr it's very simple and neat.

Have fun

Geoff Hackett
Senior Electronics Engineer

 

[Ian T]

Thanks Geoff
much appreciate your input. Being a total novice could you recommend a
starter kit or perhaps point me in the correct direction.
Cheers,