An LED show tailored for DIY initiatives

This expandable LED show for a microcontroller in Determine 1 has a easy interface with solely 6 information/management wires and may be simply accommodated to a DIY design. The show has static indication.

Determine 1 The expandable LED show for a microcontroller has a comparatively easy interface with solely 6 information/management wires.

Wow the engineering world along with your distinctive design: Design Concepts Submission Information

The primary parameters are:  

• Digits: 8 Hex digits (could also be extra, expandable)
• Information & management wires: 6 (minimal)
• Energy voltage: 3…6 V
• Energy consumption: < 3…5 mA/digit (Rlim in vary 2 ok – 2.4 ok for E = 3,3 V or, Rlim in vary 4.3 ok – 5.1 ok for E = 5 V)

If you happen to select the section present too low (decrease than ~0.7 mA) some segments might develop into a lot darker than others. For that reason, it might be sensible to examine the efficiency of your indicators with the low present.

The circuit in Determine 1 is optimized for 7 section indicators such because the A-522SR (twin, with widespread anode and super-bright LEDs) and DIP variations of the 74HC259 (8-bit addressable latch) and 74HC137 (decoder).

By putting the pair latch/indicator in shut neighborhood to at least one one other, we will strongly cut back not solely the size of the show, however the quantity of soldering as effectively. This attribute makes the circuit very appropriate for DIY designs. On this design, we will solder the Rlim resistors (SMD 0805) straight between the corresponding legs of the latch and indicator. The pin task is proven for this case.

The algorithm static LED show: Preliminary/displaying state: P3=1, P4=0, all different pins are of no significance.

The steps required to vary the info on the show are as follows:  

1. Set a digit’s tackle: P2..P0 = tackle
2. P3 = detrimental strobe 1-0-1 to latch the tackle
3. Set a section’s tackle: P2..P0 = tackle
4. Set a price of D:  P5=0 if the section have to be ON, P5=1 if OFF
5. P4 = constructive strobe 0-1-0 to latch the worth of D
6. For all the opposite segments, repeat from ranging from step 3. When all of the segments are carried out, go to step 1 whereas there are unattended digits.  

This precept may be expanded for extra digits merely utilizing a similar decoder with extra legs.    

—Peter Demchenko studied math on the College of Vilnius and has labored in software program growth.

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