IO expansion

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I would use a Shift Register, and load the data serially with one data output.
Use a second data line for the shift clock and a third to load the PLL.

--- On Sun, 9/28/08, kb5pwl <donwest@magtel.com> wrote:

From: kb5pwl <donwest@magtel.com>
Subject: [ARMexpress] 8 Bits Out To Latch
To: ARMexpress@yahoogroups.com
Date: Sunday, September 28, 2008, 3:25 AM

Has anyone written any Basic code to output 8 bits to an 8-bit data
latch? I want to use an Armmite to control a PLL chip, which requires
8 parallel data lines. One method would seem to be: write the
individual bits to 8 IO or AD pins, then pulse another pin to clock
the latch.

[YahooArchive]

> Has anyone written any Basic code to output 8 bits to an 8-bit data
> latch? I want to use an Armmite to control a PLL chip, which requires
> 8 parallel data lines. One method would seem to be: write the
> individual bits to 8 IO or AD pins, then pulse another pin to clock
> the latch.

If you have the pins available you can use 9 IOs.

' use IO(0-7) as a bus and IO(8) as strobe

FOR I=0 to 7
IO(I) = X AND (1<<I)
NEXT I
IO(8) = 1
IO(8) = 0

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Using IO() is slower as it sets the direction each time