74HC595 Help
RICoder
Posts: 91
I'm trying to use this chip to control a 7 Segment LED with a BS2 (also a prop, but I can do that once I get how it works).
My problems are thus:
1) Code-wise shouldn't I be able to just:
** set master reset low
** wait 20ms
** set master reset high
** set output enable high
** shiftout some bits like %1101
** set output enable low
...and then it pumps out the parallel data?
2) do I need to "pull" the active-low pins high on my board in order for this to work?
3) Is there something else I am missing as far as the shift registers and the storage registers, because I see that I am not touching the storage register clock pin
4) Does my psuedo-code above reset the chip to null before it fires off, or is my reset code wrong?
Any help on either or both the board layout or the code would be great.
I'd post a schematic if I had the software to draw one up on me, but I don't right now. Basically I have VSS / GROUND set up and the serial in going to a pin, as well as master reset, storage clock, shift clock and output enable all going to their own pins on the BS2, and 7 of the outputs Q1-Q7 going to the applicable A/B/C/D/E/F/G pins on the 7 segment through 1k resistors (and the common cathode going to ground on the seven segment).
My problems are thus:
1) Code-wise shouldn't I be able to just:
** set master reset low
** wait 20ms
** set master reset high
** set output enable high
** shiftout some bits like %1101
** set output enable low
...and then it pumps out the parallel data?
2) do I need to "pull" the active-low pins high on my board in order for this to work?
3) Is there something else I am missing as far as the shift registers and the storage registers, because I see that I am not touching the storage register clock pin
4) Does my psuedo-code above reset the chip to null before it fires off, or is my reset code wrong?
Any help on either or both the board layout or the code would be great.
I'd post a schematic if I had the software to draw one up on me, but I don't right now. Basically I have VSS / GROUND set up and the serial in going to a pin, as well as master reset, storage clock, shift clock and output enable all going to their own pins on the BS2, and 7 of the outputs Q1-Q7 going to the applicable A/B/C/D/E/F/G pins on the 7 segment through 1k resistors (and the common cathode going to ground on the seven segment).
Comments
I'm trying to learn to use the same part. Chris S. from Parallax is trying to help me out. I needed more I/O pins in my current board layout. My request is titled "I/O pins count increase" from a couple days ago. Chris also gave a link to his design and code that can help. Let me know how your coming along, I need all the help I can get. Also ExpressPCB.com has a great software package that is free to down load and easy to use. Hope this helps.
My current request is about six lines above yours request.
I'm sloooowly learning how to use this chip and I'm not their yet.
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I HAVE LEARN SO MUCH...BUT STILL KNOW SO LITTLE!!!
hmlittle59