Shift Registers not working?
John A. Zoidberg
Posts: 514
Hello there,
I have some 74HC595s on my hand, and wanted to try expanding the I/Os on the prop.
One issue there - it wouldn't work.
I have the pull-downs on the latch pin of the SH, and a cap of 100nF across the 74HC595 power supply, but it wouldn't do anything at all.
The CLK and the Data pin are all normally connected.
Here are the codes and the schematic...
On times, when I removed the pull-down from the Latch pin, and touched the wire, all of the outputs are high on the Shift Register and any amount of Reset applied on it wouldn't override anything back to zeros.
I have some 74HC595s on my hand, and wanted to try expanding the I/Os on the prop.
One issue there - it wouldn't work.
I have the pull-downs on the latch pin of the SH, and a cap of 100nF across the 74HC595 power supply, but it wouldn't do anything at all.
The CLK and the Data pin are all normally connected.
Here are the codes and the schematic...
On times, when I removed the pull-down from the Latch pin, and touched the wire, all of the outputs are high on the Shift Register and any amount of Reset applied on it wouldn't override anything back to zeros.
931 x 519 - 23K
spin
542B
Comments
Let me guess..
You should put OE (output active low) to ground and MR (reset active low) to VCC for permament activity.
Then try to shift in some data.
Thanks for pointing this out too.
By the way I got it working. I'll post the sample code later.
The "repeat" area in the code should be "repeat 8", not "repeat until 8".
-- http://obex.parallax.com/objects/478
Read about it. Great work.
Right now, I'm trying to cascade it. Just wanted to make myself an LED matrix display.