7segmentdisplayalternatives
I'm following a tutorial that use a MC14543B chip.
The chip is defined as "Bcd-to-7 Segment Latch/decoder/driver"
Datasheet is here: http://www.digchip.com/datasheets/parts/datasheet/343/MC14543B-pdf.php
Any advice ? What do you use to control 7 segments from the status of only 4 pins ?
Edit:
I was asked for a Schema where the BCD to 7 segment is being used:
(source: siteduzero.com)
I do not believe you can reasonably run your display (or any multi-digit common anode display) using this chip. You may be able to finagle it to drive a single digit display through some creativity by hard-wiring the common anode to VCC and not connecting any of the DIG pins of the chip.
The way the chip works is that the SEG* pins "source current to the display" and the DIG* pins "sink current from the display common cathode". The way it's meant to be wired is that the common cathode of each digit on the 7SD is wired to a corresponding DIG pin and the SEG pins are wired to the corresponding anode segment pins of the 7SD. You serially load up "what should be displayed" into the memory of the chip and some configuration settings and it takes it from there.
The chip "scans" the 7-segment display for you and does this by, for each digit N:
There's just no way you are going to be able to take advantage of the chip's multiplexing algorithm because it relies on the DIG pins driving the common cathode to GND to "enable" each digit in turn.
You could insert an inverting buffer between all the SEG and DIG pins of the chip and the display and then you would communicate with the chip and wire it up "normally" as though it was a common cathode display. Not worth it if you ask me...
Looking at this picture of the board
it looks like the displays are soldered to the board. Desoldering PTH parts from plated-through holes can be painful: you have to be sure that all the solder is removed from all the holes, and the plating-through doesn't exactly help.
The best thing you could do is try to borrow a desoldering station, where you can heat the two rows of pins simultaneously, and then pull the display. Then use a desoldering suction pump
to make sure all holes are open before inserting the new display.
If you can't get a desoldering station you'll have to use the suction pump and desoldering braid to remove the solder from the holes. In case one or more pins won't give, use a more drastic approach: cut the defective display so that you can remove the pins one by one, but make sure that you don't damage the PCB's copper when cutting.
Success!
Best Answer
It's just a 4543 CMOS IC, different manufacturers use different prefixes. RCA (the founder, for what it's worth, although TI has this now) would call it CD4543B. SGS / ST use 'HEF'. Motorola/On semi use MC(1), as in this case. Other manufacturers use different names yet.
On ebay or digikey or.. wherever, just search for '4543'.
For what it's worth though, 4543 is designed for LCDs and has piddly little output current. CD4511 is better for driving LEDs, as it can sink 25mA instead of.. a couple.