I’m an electronics newbie, so I’m trying to use a few IC's to check my understanding.
At the moment I’m trying to use a 74LS259 8 bit addressable latch. I’m trying to get it working without a micro-controller first to ensure that I understanding the wiring 100%.
But I am having a problem understanding the E and C pins … (see below)
I’ve wired it as follows:
- A0-A2 - Address inputs - wired to a switch and the +5V Q0-Q2 - Outputs
- Each wired to a LED and a 220ohm resistor
- Q3-Q3 - Outputs - Not Wired (Is this a problem should I wire them to the -5V instead)
The issue I has is understanding how to wire the E (enable) and C (clear) pins.
The datasheet says that to select the “addressable latch” mode I should have:
- E - Low
- C - High
So I’ve wired E to 0V and C to +5V.
I then try to “write” a bit by taking A0 high and then D (data) high but this does not work.
I suspect that I have wired E and C wrong. I’ve searched around but I can’t find any circuit diagrams that could help me…
Can anyone assist? What am I doing wrong here?
Here is the circuit diagram at CircuitLabs: