LED lighting

Bernard

Joined Aug 7, 2008
5,784
No mistake, not showing all Vcc, Vdd, & grounds keeps schematic functionall clearer.
74XX04, 74XX164,& 74XX74, VDD, VCC pins 14, ground pins 7
4060, VDD, pin 16, ground, pin 8
 

Thread Starter

rohitraj_91

Joined Oct 29, 2013
9
I am facing a problem with my sn74ls164 setup. I am supplying clock, active low of clear, VCC and ground and the high input to it from a micro controller. After getting the desired effect I switch off the supply to microcontroller. When I switch it on again the LEDs are on for a while before they are cleared and then they start lighting up one by one. Is there anyway to pull them down to ground or soemthing so that they are not on everytime I reset the microcontroller?
 

elec_mech

Joined Nov 12, 2008
1,500
Put a pull-down resistor, say 10kΩ, on CLR (pin 9) and connect an unused I/O pin from the uC to CLR as well. Now program the uC so that said I/O pin is LOW on restart. This should force the LEDs off. Set I/O pin HIGH when you're ready to use the 74LS164.
 
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