Re: [Emc-users] Parport Bulk Write
On Sat, Nov 06, 2010 at 03:36:42PM -0700, Kirk Wallace wrote:
On Sat, 2010-11-06 at 11:49 -0700, Kirk Wallace wrote:
I am starting to think about how to put an eight bit word on a parallel
port. My first guess is to load Parport, then write a component that
shifts an unsigned variable a bit at a time to each parport pin, but I
wonder if there is a cleaner way to write the whole (8bit) word to, lets
say, pins 2-9? This will be used with a strobe component to latch data
to an AVR port.
It turns out this is pretty trivial:
http://www.wallacecompany.com/machine_shop/EMC2/AVR/conv_u32_8bits.comp
Kirk, to grab the lowest byte of a uint32_t, I'd be tempted to just do a
typecast in an assignment:
In file: test1.c
#include stdint.h
int main ()
{
uint32_t given ;
uint8_t needed ;
needed = (uint8_t) given ;
}
$ gcc test1.c -Wa,-ahdl=test1.lst
That compiles without errors, and gives some intel assembler in
test1.lst, with (satisfyingly) a movb in the middle of it. The rest is
stage setting, AFAICT. (8 bit intel is OK by me, but I haven't grubbed
in x86, so I have to squint and guess that much of it is preamble and
postample, pushing and popping a stack frame.)
Now there's just the write of the uint8_t to the parport address, and
pulse the strobe line, as you've mentioned. (i.e. the tricky part,
unless an oscilloscope is to hand to check the (presumably) software
timing of the strobe duration.)
Erik
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[Emc-users] Parport Bulk Write
I am starting to think about how to put an eight bit word on a parallel port. My first guess is to load Parport, then write a component that shifts an unsigned variable a bit at a time to each parport pin, but I wonder if there is a cleaner way to write the whole (8bit) word to, lets say, pins 2-9? This will be used with a strobe component to latch data to an AVR port. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The Next 800 Companies to Lead America's Growth: New Video Whitepaper David G. Thomson, author of the best-selling book Blueprint to a Billion shares his insights and actions to help propel your business during the next growth cycle. Listen Now! http://p.sf.net/sfu/SAP-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Parport Bulk Write
On Sat, 2010-11-06 at 11:49 -0700, Kirk Wallace wrote: I am starting to think about how to put an eight bit word on a parallel port. My first guess is to load Parport, then write a component that shifts an unsigned variable a bit at a time to each parport pin, but I wonder if there is a cleaner way to write the whole (8bit) word to, lets say, pins 2-9? This will be used with a strobe component to latch data to an AVR port. It turns out this is pretty trivial: http://www.wallacecompany.com/machine_shop/EMC2/AVR/conv_u32_8bits.comp -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The Next 800 Companies to Lead America's Growth: New Video Whitepaper David G. Thomson, author of the best-selling book Blueprint to a Billion shares his insights and actions to help propel your business during the next growth cycle. Listen Now! http://p.sf.net/sfu/SAP-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
