Re: LPT square wave


rpodraza@xxxxxxxxx wrote:
Hi,

I'm trying to write a program in C++ to communicate with an AVR
microcontroller's SPI via the LPT port.

I have to generate a clock (SCK) signal on one of the pins of the LPT.
I am using the WinIO library. I'd like to have way to create a square
wave of a given frequency (within some limit of course).

My question is: what is the best way to generate such signal and what
is the maximum frequency one can obtain? Excluding of course such code:
Code:

for (;;) {
pin = 0; pin = 1;
}

Generating SPI with software using the PC printer port is quite easy,
just follow the timing diagram. The clock doesn't have to be a
conventional square wave, just drive it high and low at the correct
time with the data line held high or low. Connecting a 74HC595 with
LEDs on the outputs to the printer port can be useful when debugging
the software, the 74HC595 is SPI-compatible and makes it easy to see
when you have got it right. I have one mounted on a small PCB with the
LEDs.

Leon

.

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