Banana Pi LCD Display Setup

In this tutorial we’ll be setting up the LCD display and the Raspbian OS for the LCD display. We’re using the 7” LCD monitor/touch display and the Banana Pi M2 single-board computer with integrated WiFi.

Step 1) First we’ll set up the Raspbian OS.

  1. Connect the MicroSD card to your computer and locate the Raspbian OS (LCD) image.
  2. Click the Google Drive logo and download the image (this may take awhile depending on your internet connection). Make sure you download the version for LCDs — the LCD will not work if you have the version for HDMI.

Step 2) If this is your first time setting up a Banana Pi, we recommend going over our first tutorial.

Windows users will use Win32DiskImager or a similar program to burn the image file to the SD card.

If you’re using a Mac or Linux follow these steps:

  1. Open up your terminal by
  • opening up your finder
  • selecting applications
  • typing in “terminal”
  • open the application with the >_ logo
  1. To find your SD card on your computer. Type in (diskutil list) in the terminal without the parentheses. This will give you a list of your storage devices.  Locate the name of your SD card that you inserted earlier.
  2. Un-mount the card by entering the following command: (diskutil umountDisk /dev/disk1). This is just an example file path, your root file will be located above the storage information of your SD card. In this case mine was /dev/disk.
  3. Once you’ve unmounted the card, run the data dump command to burn the image to the SD card: (sudo dd bs=1m if=~/Downloads/rasbian.img of=/dev/rdisk1).  For this command replace the “/Downloads/rasbian.img” with the file path the raspbian image file located on your machine.  Also replace the “/dev/rdisk1” with the path that you raplaced in step 3- make sure to keep the “r” before the disk#.
  4. Enter your password and wait for the data dump to finish.
  5. Eject your disk (sudo diskutil eject /dev/rdisk1), then replace the filepath with the one you replaced at the end of step 4.

Step 3) Next we are going to connect the Banana Pi 7” LCD display. The first step is to take the ribbon cable and connect it to the port near the Banana Pi logo (the one that has the long black tab). To do this simply lift the black tab and carefully insert the ribbon and then close the black tab, securing the ribbon in place. Be sure to have the blue side (with the labels) facing the Ethernet port.

Step 4) After connecting the ribbon to the Banana Pi, we need to connect the ribbon to the LCD display. Locate the corresponding port near the bottom of the board on the back of the LCD module. Flip open the tab and insert the ribbon with the blue side (without the labels) facing away from the LCD. Once more, secure the ribbon by closing the tab.  When you’re finished with this step, it should look like this.

Display banana pi

Step 5) Once this is done insert your SD card back into the BPi and power it up using the 5V power adapter. Because the micro-USB cannot support all of the functionality on the board — especially the LCD display — we prefer to use a 5V power adapter. Once you’ve connected the power supply, your LCD display should be ready for use.

Measure AC Current with a Digital Panel Meter (DPM)

Digital Panel Meters (DPMs) are strictly DC meters due to the digital circuitry used. Oftentimes it is desired to utilize a DPM to measure AC voltages and currents to take advantage of the improved accuracy and readability of a DPM. This application note will describe a method to accurately display AC current values on a DPM using a current transformer.

The PM128E Digital Panel Meter from Circuit Specialists is ideal for this application, as it is designed to use in a system that has the measured signal isolated from the power supply voltage. The application is for a 0-20 Amp AC meter powered by an external 9 volt battery. This application could also be powered by a “wall-wart” type of AC adapter if desired.

The PM128E DPM is a universal unit with all built in divider resistors and rectifier circuitry to allow AC voltage measurements with no external components required. This meter can be used to display AC current values with the use of a low cost current transformer and load resistor. The current transformer used is a low cost device with a 1000:1 current ratio capable of operation from 0-100 Amps.

A wire with the the AC current to be measured is simply passed through the center of the transformer with the transformer secondary winding connected across a 1.1K ¼ watt resistor so that the transformed current value will be converted to a voltage that can be read by the PM128E DPM in AC voltage mode of operation.

The settings for the PM128E meter should be J3 and J5 shorted with the P1 decimal point location shorted and the AC and 200V points also shorted. This will put the DPM in AC voltage measuring mode with a 200 V full scale reading and set for operation from an isolated 9 V DC power source. The display will read in AC Amps with 0.1 Amp resolution.

The complete implementation of this circuit is included for reference.


This application note has shown how a Digital Panel Meter may be used to measure and display AC current values using a low cost current transformer.

DIY: Electronic deadbolt with a servo motor

We recently added servo motors in a variety of sizes and torques to our product listings.  Servo motors are dc motors with integrated encoders that can rotate to specific locations.  They are commonly used in robotics, tracking systems, cutting & forming machines, and automatic door openers.  The advantage of a servo motor over a stepper motor or dc motor is that they provide feedback so they can return to specific locations with great accuracy.  The servo motors we offer can rotate between 0-180 degrees.

After doing some market research, we realized that low cost, high functioning electronic servo locks were scarce.   This motivated us to build our own electronic deadbolt that would be secure and easy for someone with basic knowledge of electronics to build.  Not only is this project one you could use at home but it is a good way to learn more about motors, RF communication, and Arduino.



The original deadbolt we would replace with an electronic lock.


After removing the faceplates of the deadbolt we see the hardware that holds the door latch.  We will reuse this.IMG_8127

The external lock is mounted to a flat shaft that locks and unlocks the deadbolt when rotated.  This shaft must be shaved down or cut to fit the new depth of the servo motor.IMG_8130

We use an MG959 servo motor mounted to 2 servo mounts, using rivets supplied with the servo mount to clamp them together.IMG_8133


We found some scrap sheet metal for mounting the servo motor to the door, we purchased a plastic round to rectangular adapter from Ace Hardware to adapt the motor shaft to the rectangular cantilever on the door deadbolt.IMG_8135

Josh examines the servo motor prior to mounting it in place.IMG_8227


The servo motor mounted in place.IMG_8215


We mount the servo motor, wire it to a breadboard and Arduino on the left side of the door.


We use a 5V switching power supply to convert 120V electrical load into usable 5V by the motor and Arduino.IMG_8230

The OSEPP Arduino compatible UNO R3 Plus and breadboard to control the servo motor wirelessly.


Parts List

OSEPP Arduino Uno R3 Plus

MG959 servo motor, PS1-25W-05 power supply

RXD4140-434 4CH remote & receiver


RA10K x 2 pc.

Scrap sheet metal

All thread (Hardware store)

Bolt/Screw fasteners (Hardware store)

JB Weld (Hardware store)

22 ga wire



#include <Servo.h>

Servo myservo;
const int buttonPin = 2; // the number of the pushbutton pin
const int buttonPin2 = 3;
int buttonState; // variable for reading the pushbutton status
int buttonState2;
void setup()
myservo.attach(9); // attaches the servo on pin 9 to the servo object

void loop()

while (buttonState == HIGH && buttonState2 == HIGH)
buttonState = digitalRead(buttonPin);
buttonState2 = digitalRead(buttonPin2);
if (buttonState == LOW)
buttonState = HIGH;
buttonState2 = HIGH;
if (buttonState2 == LOW)
buttonState2 = HIGH;
buttonState= HIGH;



What is an Android OTG Device?

For the SmartScope USB Oscilloscope from LabNation to work with Android phones and Tablets they are REQUIRED to support USB OTG (On The Go) functionality.


Simply put, USB OTG (On The Go) enables mobile devices, like smartphones and tablets, the ability to function as a USB Host Device for communication with devices like mice, keyboards, flash drives or other devices provided the host device is capable of providing enough power to run the device connected. Some OTG compatible peripherals can function correctly by using a powered USB hub if the host device doesn’t supply enough power.

We have searched the web for a list of devices that offer OTG functionality,  It is not complete and we have no way of testing every device out there that claims OTG support.  OTG support was introduced in Android v3.2 (Honeycomb), but some manufacturers did not elect to support the feature.

There are Apps that can test a device to see if the required drivers are installed. They can be found by searching for “USB OTG” on the Google Play Store.

Here is a partial list of OTG Supported Devices.   (Unconfirmed by Circuit Specialists)

MeMO Pad 10 ME102 MeMO Pad ME172V MeMO Pad ME301T MeMO Pad ME302 MeMO Pad 8 ME180A
MeMO Pad 10 ME180A MeMO Pad FHD 10 LTE MeMO Pad FHD 10 Transformer Pad TF700T Transformer Pad 701T
Transformer Pad TF-100 Nexus 7 (need” “Nexus Media Importer” app) PadFone PadFone 2 PadFone Infinity
Z30 Passport
MediaPad S7-301u(P) MediaPad 7 Lite P6-00 Youth Vogue
MediaPad 10 FHD Ascend D2 Ascend P1 Ascend P6 Stream X GL07S(Japan)
Butterfly Butterfly S Desire (A8181) Desire VC T328d One Dual
One mini HTC J (Z321e) One (M8) One Max One X
Lenovo LePhone P770 Lenovo Vibe Z K910 Lenovo Vibe X S960 IdeaTab A3000 IdeaTab A1000
IdeaTab S6000
Nexus 5 Optimus G Pro Optimus G Pro lite G2 (D800) G2 (D802)
Droid Razr HD (XT926)
Galaxy Note 8.0 Galaxy Note (GT-N7000) Galaxy Note II (GT-N7100) Galaxy Note III (GT-N900) Galaxy Note IIII
Galaxy Note 10.1 (2014 Edition) Galaxy R (GT-I9103) Galaxy J Galaxy S2 Galaxy S3
Galaxy S4 Galaxy S5 Galaxy S6 Galaxy Tab Pro 8.4 Galaxy Tab Pro 10.1
Galaxy Tab 3 8.0 (SM-T310) Galaxy Mega 6.3 (GT-I9200) Galaxy Mega 6.3 (GT-I9205) Galaxy Ace Galaxy Ace 2
Galaxy Ace 3
SGPT111JP/S SGPT112TW/S SGPT211JP/S Xperia AX (SO-01E) Xperia ACRO S (LT26W)
Xperia T (LT30P) Xperia TX LT29i Xperia Z2a Xperia Z (C6602) Xperia Z ULTRA (C6802)
Xperia ZL (C6502) Xperia ZR (C5502)
Red Rice Red Rice Note


Advanced Features of the New Hantek DSO5102P Oscilloscope

The Hantek DSO5102P 100MHz 2-channel digital storage oscilloscope offered by Circuit Specialists boasts advanced features you won’t find on most analog oscilloscopes, especially at a price point this low. These unique functions are useful for troubleshooting glitches and dropouts in complex digital data as well as identifying problems in analog signals up to 100 MHz. Let’s go over a brief tutorial that illustrates the usefulness of pulse mode triggering and fast-Fourier transform (FFT) display mode.

Pulse mode triggering is useful for detecting digital signal abnormalities and troubleshooting elusive digital signal corruption. In pulse mode the user has the option to select the trigger signal based on the width of the pulse of interest. The choices are “equal to,” “not equal to,” “less than,” and “greater than” an adjustable pulse width ranging from 20 nanoseconds to 10 seconds.

Let’s take a look at how to use pulse mode triggering to detect a runt pulse in a digital pulse train. Select pulse mode triggering from the trigger menu and choose the criteria (“equal to,” “greater than,” etc.). You can then dial in the specific pulse width by first pressing F4 to activate the pulse width control and adjust it using the V0 knob. In our example we’ll select the “less than” criteria and adjust the pulse width to 20us, which is the pulse width of a normal pulse.

This enables us to immediately detect runt pulses produced by a defective integrated circuit. Detecting and identifying runt pulses with an oscilloscope that doesn’t have this feature is extremely difficult and time-consuming, requiring countless hours of tweaking the trigger level control in an attempt to catch the runt pulse. The oscilloscope screenshot below shows a stable signal train indicating the presence of the non-standard runt pulse.

Runt pulse

The Hantek DSO51102P digital storage oscilloscope also features fast-Fourier transform (FFT) display mode, which provides you with a means of easily detecting distortion in an analog waveform. This FFT feature enables you to view a waveform in voltage-versus-frequency instead of the standard voltage-versus-time typically found on most oscilloscopes. You will use this mode of operation to quickly determine the harmonic content of a periodic signal. For instance, a pure 1 KHz sine wave should produce an FFT display with frequency content only at 1 KHz.

Pure sine wave in FFT display mode

Since a pure sine wave is unobtainable in reality, a real waveform will show minimal frequency content at other frequencies that are multiples of 1 KHz — 2 KHz, 3 KHz, 4 KHz, etc. — and a distorted waveform will have significant frequency content at its multiples. Harmonic distortion would then produce a waveform with excessive amplitude values above 1 KHz. The screenshot below shows a 1 Khz since wave applied to an amplifier that is producing distortion.

Distorted sine wave

The FFT display of the distorted signal shows excessive amplitude at 3 Khz. The display of the same waveform viewed on the standard oscilloscope display is included to show that the level of distortion is not as obvious as what we see on the FFT display.

Distorted sine wave without FFT display mode enabled

The examples above were used to highlight two of the many features that make the Hantek 5102P digital storage oscilloscope an incredible value. These features will prove invaluable the next time you need to debug or troubleshoot complex digital and analog circuits.

View the Hantek DSO5102P product page >

An Oscilloscope That Fits in Your Pocket

The LabNation SmartScope is an extremely versatile digital storage oscilloscope that transforms your smartphone or tablet into a full-featured DSO. This unit features a powerful set of protocol decoders usually only found on pricey mixed-signal oscilloscopes or logic analyzers.  An example of the usefulness of this feature will be presented in the real-world application of a wireless communication link using the RS232 asynchronous serial bus.

A system for a remote paging was designed using the RF modules from Circuit Specialists. The STPA-418 transmitter and RXB4411S-418-RH receiver were chosen due to their low cost and simplicity of use. An asynchronous serial protocol is required for communicating data over an RF link and is easily created with the UART of any microcontroller such as an Arduino-compatible board  or PIC.

Since we live in a wireless age, we are continually bombarded by myriad RF signals from cell phones, WiFi networks, and radio communication systems. These RF signals can create false signals on our paging system, so our circuitry must be able to differentiate between valid and invalid data. This is where a protocol decoder was found to be invaluable as we can see at a glance the decoded value of the data received.

If a protocol decoder is not available, we must count rising edges and write down logic 1s and 0s, which must then be manually converted into the corresponding hex value of the data. The protocol decoder automates this entire process and even translates this value into humanly readable words specific to your application code. This feature is unique to the SmartScope among the various oscilloscopes and logic analyzers available from Circuit Specialists.

The example shown illustrates the usefulness of the unit in tracking down garbled data caused by RF interference in the environment.  To ensure that the received data was valid, a series of start bytes are transmitted, which are used to synchronize the receiver and set up the automatic level control (ALC) circuitry of the receiver. Next, a preamble consisting of a series of digital words of a known value is sent. The digital words are used to differentiate valid data and random noise. Finally, the actual data is sent and repeated several times as a final error checking method.

As can be seen from the attached screen shots, the first received byte was garbled and therefore not correctly validated. Many hours were wasted trying to determine the reason that our system was missing data. Once the protocol decoder was implemented, it was only a matter of minutes to see the incorrect data in the received data stream.

The LabNation SmartScope is a compact yet powerful digital storage oscilloscope that transforms your smartphone or tablet into a powerful debugging tool. The built-in protocol decoders are invaluable when troubleshooting modern data communications.

New Opportunities for DIYers at Circuit

I like to dabble in many different crafts and hobbies; from  LED design and home automation to basic soldering and programming.  In my opinion you can never learn too much or have too many ideas, or interests. A problem I seem to have though is my finances never quite match my drive. Let me explain: While knowledge and desire to learn, in any craft, are priceless, often times we find the equipment needed to execute these goals are price-FULL; with soldering and electronics design being no exception. Fortunately for DIYers like myself Circuit Specialists has a solution: The Learner’s Lab. This new service offered by Circuit Specialists is available to any local hobbyist, assemblist, prototyper, or solderer and is the answer to the problem that we all face: What do we do when we don’t have the resources to finish this one project or the disposable finances to acquire all the tools we may need for a single job? Well now you can come into our shop and use virtually any item we have for sale in order to complete your project or perhaps even get some hands-on feel for a product you were considering purchasing.

What the Learner’s Lab is, is a multi faceted program introduced by Circuit Specialists in order to help provide you whatever level of assistance you may need. The basic core of The Learner’s Lab is to provide participants access to virtually any item Circuit Specialists has for an allotted amount of time monthly for a small recurring fee. What this is is basically a gym membership for your brain! Rather than stressing off how you can afford that 4-channel 200mhz Oscilloscope or Hot-air Station in order to complete your project all you do is head on down to Circuit Specialists and become a member. What’s even better is the fact that that this access to hundreds of items is available for only $25/month to the first 10 people that sign up! We don’t expect this deal to last, and prices for access WILL RISE so if you’re interested in this deal make sure you get filled in on all the details quickly! Simply head down to Circuit Specialists and talk to Josh or Sam and let them answer any question(s) you may have.



Circuit Specialists is dedicated to the knowledge of electronics assembly and the growth of the Maker’s Movement going on around the world right now and especially here in Arizona. Now while the main idea behind the Learner’s Lab is based off giving the knowledgeable an area to create, test, and design we also understand that there are many people who don’t know the basic skills required to proceed. That is why we will also be offering simple instructionals on the use and procedures behind some of the products available, like digital multimeter uses/applications and soldering techniques, for a small additional fee to those that may need some sort of instruction or direction in their assembly journey. If you feel these services would benefit you go ahead and get filled in on all the details simply by coming on in to our new store or calling ahead.

The third part of the new Learner’s Lab amenities offered by Circuit Specialists will be a Consulting Service. This service is offered for those people who need work done for them, whether it be repair, design, or assembly; Circuit Specialists will be able to help assist you in any endeavor as we see fit. Simply bring in your design or item that needs repair and let us take a look at it in order to give you a fair and honest assessment as well as a quote for what we predict labor and parts prices might be.

There are big things happening in this Maker’s Movement and plenty of ways to get you the services and assistance you might need. You may have always felt like the only thing holding you back from starting that project that’s been on your mind was the lack of resources or equipment needed due to financial constraints. Well, don’t let that hold you back any longer! Come into Circuit Specialists today and join the Learner’s Lab so we can create together!! See you soon!

4x4x4 LED Cube Tutorial

ledbox-0Here at Circuit Specialists we like to build, create, and design projects that can be both educational and fun. Ever since we started carrying the Arduino UNO compatible OSEPP UNO R-3 Plus, we have been searching for different applications for which this microcontroller is well-suited. After scouring the internet for projects that require no prior programming experience and limited soldering skills — not to mention a cheap, fun, and entertaining project — we finally settled on the 4x4x4 LED Cube.

The 4x4x4 LED Cube is a simple Arduino project that can easily be manipulated or left as-is to produce mesmerizing LED patterns and effects that will leave your guests impressed with your design, programming, and soldering skills. All the parts used in this project have been combined in a single kit that we offer at Circuit Specialists called the LED Cube.

This design is based on an Instructable by the user “Kyle the Creator”. You can find his actual project by clicking on this link: 4x4x4 LED Cube. I had the pleasure of working on this project for Circuit Specialists and let me tell you what — the pictures, descriptions, and step-by-step instructions from Kyle’s tutorial combined to make it one of the simplest and easiest to follow that I have ever encountered online.

After printing out the PDF template for the LED pattern found in Kyle’s Instructable and gathering all the parts from Circuit Specialists’ on-hand inventory, I got to soldering. Because it was a job requiring a lot of soldering and multiple hands, I wholeheartedly recommend picking up a helping hands unit. It saved me a lot of time and spared my sanity. In fact, I used the ZD10Y helping hand from Circuit Specialists so much I even wrote a blog on just how useful this particular unit is. At the time of this blog’s publication, Circuit Specialists offers three other types of helping hands at very reasonable prices.

I had a blast recreating this 4x4x4 LED cube and am excited that Circuit Specialists has become a forerunner for supplies in the current Maker Movement — now all us do-it-yourselfers have a reputable company with low prices and high-quality products where we can find everything we need for all our projects. I hope that you all enjoy this project as much as I did! Before you get started, please check out video above of the cube I created in action. Take care, solder safe, and keep on creating!

Powered breadboard, Arduino, and a seven segment display

Prototyping can be easy with the right tools.  In this project we built a seven segment display countdown timer using an OSEPP UNO R3, a seven segment common cathode display, our powered breadboard, a 220 ohm resistor, and wire jumpers  .  We used the
Arduino code provided in the Instructable Seven Segment Display Tutorial and found some inspiration in that post.

In order to complete this project as we did you’ll need to connect segments A-G to digital output pins 2-8 on the OSEPP UNO respectively.  You can determine which line segment corresponds to which pin using our pin out diagram on the seven segment item page (or by supplying 5V to test each segment and using the guide below).  You will also connect pin dp to digital out 9.

seven segment

Next you will connect the two common grounds on the cathode display to the 220 ohm resistor then connect that resistor to ground on the powered breadboard.

Once it is all wired you will upload the code below to your OSEPP board and then set your powered breadboard to 5V and power tie the breadboard into the 5V and ground terminals of the OSEPP UNO.

The countdown timer will begin a countdown from 9 to 0, you can adjust the speed and functions in the Arduino code.  Hopefully you’ve learned a bit more about seven segment displays, prototyping, and the convenience of our powered breadboards.  See our countdown in the animated picture below.


// Define the LED digit patters, from 0 – 9
// Note that these patterns are for common cathode displays
// For common anode displays, change the 1’s to 0’s and 0’s to 1’s
// 1 = LED on, 0 = LED off, in this order:
// Arduino pin: 2,3,4,5,6,7,8
byte seven_seg_digits[10][7] = { { 1,1,1,1,1,1,0 }, // = 0
{ 0,1,1,0,0,0,0 }, // = 1
{ 1,1,0,1,1,0,1 }, // = 2
{ 1,1,1,1,0,0,1 }, // = 3
{ 0,1,1,0,0,1,1 }, // = 4
{ 1,0,1,1,0,1,1 }, // = 5
{ 1,0,1,1,1,1,1 }, // = 6
{ 1,1,1,0,0,0,0 }, // = 7
{ 1,1,1,1,1,1,1 }, // = 8
{ 1,1,1,0,0,1,1 } // = 9

void setup() {
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
writeDot(0); // start with the “dot” off

void writeDot(byte dot) {
digitalWrite(9, dot);

void sevenSegWrite(byte digit) {
byte pin = 2;
for (byte segCount = 0; segCount < 7; ++segCount) {
digitalWrite(pin, seven_seg_digits[digit][segCount]);

void loop() {
for (byte count = 10; count > 0; –count) {
sevenSegWrite(count – 1);
if (count == 1){

Battery Monitor for Automotive or Marine Applications

The PM128E Backlit Digital Panel Meter from Circuit Specialists can be easily modified to produce a self-contained 2-wire panel meter capable of monitoring battery voltage in any application in which a battery’s voltage is within the range of 6-24 volts. The PM128E digital panel meter was chosen for its ease-of-use and -configuration as well as the backlight feature, which enables the user to read the panel meter at night. panel_meter-0


This digital panel meter is configured in a 5 volt powered common ground DC application with a 20 volt maximum reading, which we’ve accomplished by setting jumpers to DC and 20V and enabling the P2 decimal point. To make this unit self-powered, we have soldered in a 78L05 Voltage Regulator across the power connections and derived the input voltage from the IN terminals of the meter.


The meter and added circuitry were assembled in a PB-3P plastic project box to protect the circuitry and connections. The meter also could’ve been mounted directly in a vehicle or boat’s dashboard or control panel.


We are always looking for ways to use our own products around our facility here at Circuit Specialists, and this panel meter project quickly found a home on our trusty forklift.  The forklift’s battery is often low due to the heat in the warehouse (we are located in a desert, after all).  We attached the leads to the battery’s terminals, and just a simple lift of the “hood” shows the voltage of the battery.  We could have mounted it on the dash of the forklift, but having it under the hood gives the operator an incentive to check the battery’s water level more often, too.

Simply smart circuitry since 1971.