Re: [EE] 74HC595 continued... by brusque.

Hello Stephen, > You should remember that the 595 series has 2 clocks. You need to be > sure that the latch clock isn't getting any glitching. That's what you > should be checking with your scope. It sounds to me you are getting a > glitch while you are shifting bits into the shift register. This is > likely loading your bit pattern on each of the next LED's. Even if it > happens just after you start shifting new data in. It's still a > problem. So I would check to see if the output latch is being toggled. that's it! I've found the latch line to be very noisier. The problem was on the power supply. It's a LM2576 based switching regulator that receives 24VDC and lowers it to 5V. This was solved with a higher inductance indutor. Also, in my tests I've found it can be good to have a 100pF ceramic cap across latch and GND pins on the last HC595. I'm thinking about putting one 100pF cap on clock line too. Thank you very much and thank to everybody that replied me. Best regards, Brusque -- --------------------------------------------------------------------- Edson Brusque C.I.Tronics Lighting Designers Ltda Research and Development Joinville - SC - Brazil http://www.ryan.com.br/netiqueta.htm http://www.citronics.com.br ---------------------------------------------------------------------