I am retired and decided to play around with an electronic kit. I bought the Ultimate kit with Arduino Uno. Lots of parts and no instuctions.
I search on the web and found a book "Getting Started with Arduino" I now know how to program and make the single LEDS flash anyway I want to. I built traffic light with pedistren cossing. (I program industrial controlers for a living) the rest of the book is devoted to someother board and a sprinkler system. I live in a retirement home. I get that the book and Arduino is to help make you think. I have never wired or program LED display or stepper motors nor do i know what some of the parts are that came with the kit. Enoght of this crying.
My current problem is trying to work with the 4 digit 7 segment LED that came with the kit. I have found several example to wire and program the display with the board that I have. Problem is they have more pins then i do and i do not know the pin layout. The LED is SH5463AS this is a 12 Pin chip not 16 that I keep finding on the web. Some use diferent size resisters and other use transisters. I need to learn some basic facts.
I do have an electrical backround. I learned tube theory. very little digit theory. School during the 50's.
This is an example of how to drive a 7 segment LED display from an ATmega
without the use of current limiting resistors. This technique is very common
but requires some knowledge of electronics - you do run the risk of dumping
too much current through the segments and burning out parts of the display.
If you use the stock code you should be ok, but be careful editing the
brightness values.
IMO the above is hogwash. USE CURRENT LIMITING RESISTORS.
I think Grumpy_Mike as a good article on this topic. I'll try to find it and post a link.
There are several web sites and schematics on the web that suggest you can attach an LED directly to an Arduino output pin with no current limiting resistor. They are wrong, and following them will damage your Arduino. Their logic goes something like “the arduino will limit the current” or “as you are multiplexing the LED (turning it on and off rapidly) the circuit won’t heat up enough to burn anything out”. They are wrong.
I am retired and decided to play around with an electronic kit. I bought the Ultimate kit with Arduino Uno. Lots of parts and no instuctions.
I search on the web and found a book "Getting Started with Arduino" I now know how to program and make the single LEDS flash anyway I want to. I built traffic light with pedistren cossing. (I program industrial controlers for a living) the rest of the book is devoted to someother board and a sprinkler system. I live in a retirement home. I get that the book and Arduino is to help make you think. I have never wired or program LED display or stepper motors nor do i know what some of the parts are that came with the kit. Enoght of this crying.
My current problem is trying to work with the 4 digit 7 segment LED that came with the kit. I have found several example to wire and program the display with the board that I have. Problem is they have more pins then i do and i do not know the pin layout. The LED is SH5463AS this is a 12 Pin chip not 16 that I keep finding on the web. Some use diferent size resisters and other use transisters. I need to learn some basic facts.
I do have an electrical backround. I learned tube theory. very little digit theory. School during the 50's.
A 4 segment display is usually wired something like this
with either a common cathode for each digit, or a common anode for each digit. Use a 1K resistor from 5V and a wire to gnd to figure where your anodes and cathodes are to see which kind you have, and where the segment pins are and where the common pins are.
If cathode, you will drive the anode from 7 pins, each with current limit resistor, and sink one cathode low, for 2-3mS, , ,turn the cathode off, then do the same for the next digit, and repeat for 4 digits.
Do not let any one IO pin sink or source more than 20mA. I.e. if you sink the cathode with a pin, then limit each anode current to 20/7 mA.
If you use a NPN transistor to sink the current, you can drive more anode current and have a brighter display.
CrossRoads Thank you for the response. But I have no idea as to what you are saying. Maybe I should stayed retire. I know that I can lick this and once I do i'll fly with it. but getting started is proving difficult.
I hook a wire to the 5V pin then to my breadboard through a 1K resistor, where does the other side of the resistor go?
OK I ran a wire from 5V to a 1K resister. I also ran a wire from pin 12 to ground. when I touch a wire to pin 1 the first digit bottom left light comes on. What does that tell me? According to the print out that is E. Correct?
Welcome Naneen.
There are a few retirees here.
Another book of interest is Arduino Cookbook:
Starting with Crossroads PDF file, take a ~270 ohm resistor and 5 volts to test each segment in each digit.
This will give you some confidence and insight into the display.
+5v ----- 270 ------- a segment pin ------- cathode pin to ground
Not sure what L2930NE is. If it is another code for L293D, you might be able to use that. L293D is really for driving small DC motors, but it has 4 outputs and you have 4 common cathode pins...
OK I wired my board according to the LarryD print. And I copied the program by LarryD but no luck. I have recheck my wiring several times. If I check volts between GRN and Collector of the transistor should I read 5VDC?
First assumption is the drawing does refer to your specific display.
You will see 5v collector to emitter (GND) when the transistor is turned off (no base current).
You do have D2-12 on the Arduino connected the the resistors as per drawing and you do have the Arduino program running on the controller?
What happens if you place a wire from display pin 12 to ground? (a-g must have 470 ohm resistors)?
Have you confirmed the pin out of the display?
For segment a
+5v ----- 470 ------- segment a pin11 ------- cathode pin12 to ground (then 9,8,6)
For segment b
+5v ----- 470 ------- segment b pin7 ------- cathode pin12 to ground (then 9,8,6)
