![]() To pinpoint the issue, all I needed to do was isolate the pins that were giving problematic output. These extra pins were somehow causing a problem. He took them by using all the digital pins and all the analog pins too. On Allan’s new board, he needed an extra 4 pins - two for the buttons, and two for the RTC. There are only 12 digital pins, so on my original board, I used four analog pins (A0 to A3) making up 16 for the SN74LS47N chips. Two pins for the RTC - I2C pins A4 and A5.For input pins to each of four SN74LS47N chips - 4 x 4 = 16 pins.As most of us know, the analog pins can also be used as digital pins, but not vice-versa. This is the pinout to the Nano I am using.Īs you can see, the digital pins run from 2-13 (leaving 0 and 1 for RX and TX), and the analog pins are A0 - A7. That's when I hit on using four regular LEDs. If I could 'see' the output from the pins, I could find out which weren't working. Sixteen pins of the Nano fed into four SN74LS47N chips - which then controlled the output to the 7-segment display. I had a brainstorm while I was constructing this project I’d side-tracked into making a simple binary counter.īy controlling four binary inputs, I could get up to 16 outputs - and that’s how I controlled all four 7-segment LEDs on a single Arduino Nano. But as I listened patiently to Allan's instructions, I found my mind wandered looking for an easier way. It’s made just for this type of amateur troubleshooting. I’ve written about this little oscilloscope before. Like the engineer that he is, he went on to describe at great length how the oscilloscope could be used to identify the problem. “Use your oscilloscope to see what’s coming out of the pins.” “I think you need pullup resistors,” advised Allan by VoIP from the other side of the world. Everything seemed properly connected, but no matter what I did, I couldn’t stop the jumping numbers. I assumed a wrong connection or a poor solder joint, so I went around everything again, checking and re-checking.Īn hour later I was no further on. As Usual, Something’s Wrong Arduino Nano Pinout Explainedįor some reason, my display wasn’t working properly digits jumped around seemingly at random. Once I was happy everything was in order, I powered up. Because of the new pin allocations, we’d need to re-program the Arduino sketch - but that’s for later.Īfter soldering everything, I carefully checked the new pin numbering and made my adjustments to the sketch. When the PCBs arrived, I got to work soldering the parts in place. (Note these numbers because they become critical later). To make the PCB traces neat, Allan exchanged a couple of my original digital pins with analog pins A6 and A7 instead. With both top and bottom layers, it's a bit hard to view, but essentially, the new board incorporates the original Nano, an RTC3231, and a couple of buttons. All we’d do is plug the board into our new PCB. We decided to use an existing RTC board that we had lying around, instead of recreating its circuitry on our own. The new board would incorporate the original Arduino Nano and an RTC3231. We set about making a new daughter board to replace the one I'd made to connect the Arduino to the chips I was using to control the LEDs. When co-blogger, Allan, saw my setup he insisted on attaching a Real-Time Clock (RTC) and buttons so that the unit could be used for timekeeping and as a programmable counter. Input and Output Each of the 14 digital pins on the Arduino Uno can be used as an input or output, using pinMode, digitalWrite, and digitalRead. #Elegoo arduino nano pinout PcThe Elegoo Nano has a variety of facilities for communicating with a PC or other microcontrollers. The Elegoo Nano can be powered via USB connection, 6-12V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). After figuring out the pin locations, the wiring, and the code, I attached an Arduino Nano to a daughter board to create a beautiful self-contained 4-digit display. A few months ago I documented the process for creating a large 7-segment LED display. ![]()
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