Arduino with Optocouplers

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There are many types of optocoupler and you chose one based on the requirements of your circuit. My intention was to create a automatic shutter trigger for my Canon camera, so the circuit was a 5V Arduino and a Canon 40D which has about 3.2V on the shutter release connections. Due to the relatively low voltages there are many suitable optocouplers to pick from. I already had a Fairchild 4N26 so this is the one I used.

4N26

4N26

Optocouplers are digital switches. They work by using an LED emitter paired with a photo detector transistor. This means they can be used to allow one circuit to switch a separate circuit without having any electrical contact between the two. Basically, if you put a current through pins 1 and 2 and light the LED the photo detector transistor detects the light from the LED and allows a current to flow through pins 5 and 4. No current on pins 1 and 2 means current does not pass through pins 5 and 4.

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HM-10 Bluetooth 4 BLE Modules

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Since I first posted about the HM-10 the firmware has been updated many times and some of the commands have changed. Therefore, I decided to redo the guide. For the main article I am using modules with firmware 5.49 (regular) except the one I am using for the firmware update guide which started with v5.40 and become 5.47.

There have been several firmware updates since this guide was written, as of March 2020 the latest is v707.

 
Updated 2019-08-25
I thought it was time for a minor update.

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HC-06 hc01.comV2.0

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HC-06_hc01.com_02_800

ZS-040_HC-06_hc01.comV2.0

The latest zs-040 HC-06 modules have an updated firmware, hc01.comV2.0. This firmware has the following defaults:
– baud rate = 9600
– password = 1234
– nl/cr line endings not required.
– AT commands are required to be in upper case
– Firmware version = hc01.comV2.0
– Name = HC-06
– No parity
– SLAVE mode

Since the Bluetooth hardware is the same as the previous zs-040 HC-06s the Bluetooth specs are also the same. Bluetooth 2.0 EDR, SSP.
These use a slightly different BT module than the other zs-040 boards and there is a blue LED at the top left of the daughter board.
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Arduino to Arduino by Bluetooth

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Updated 12.06.2016: Added example 2

In the Connecting 2 Arduinos by Bluetooth using a HC-05 and a HC-06: Pair, Bind, and Link post I explained how to connect a HC-05 to a HC-06 so that when powered they automatically made a connection. Here we look at using that connection to get Arduinos talking over Bluetooth. Before continuing you need to have the Arduinos and BT modules set up as per the previous post. Here I am using 2 HC-05s. One in master mode the other in slave mode. The setup process for the slave mode HC-05 is the same as the HC-06 in the previous post.

Arduino2ArdionoBT_Breadboards_01_1600

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Bluetooth Modules

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Updated: 21.07.2017

new Bluetooth Modules

There are many very similar Bluetooth modules available and sometimes it can be difficult finding out, not only which one you have, but also how yo use them. Here I look at some of the modules I have and try to show the basic settings.

Getting Started
Connecting To A Computer
Android Apps

Bluetooth 2.0/2.1 EDR Modules
    HC-06 (ZG-B23090W) Bluetooth 2.0 EDR modules
    HC-05 (ZG-B23090W) Bluetooth 2.0 EDR modules
    SPP-C HC-06 / BT06 HC-06
    HC-06 zs-040 hc01.com v2.0
    HC-05 zs-040 hc01.com V2.1
    HC-05 FC-114 and HC-06 FC-114
    HC-05 and HC-06 zs-040 Bluetooth modules

Bluetooth 4 / BLE Modules
    HM-10
    HM-11
    BT05-A mini BLE Bluetooth V4.0 iBeacon
    AT-09 Bluetooth V4.0 CC2541

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ESP8266-01 Bread Board Adapter

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Update: 2017-01-15
Although the below adaptor works I found it inconvenient. The rear connectors are blocked by the ESP8288. I therefore built a ESP8266 bread board adaptor version 2

After a lengthy pause I have started playing with the ESP8266 modules again and I was getting annoyed by all the wires when using them on a bread board. So, like others before me, I built a small bread board adapter.

ESP8266BreadbaordAdapter_03_1600

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Android MIT App Inventor – Auto Connect To Bluetooth

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In a previous post I showed how to connect an app inventor Android app to a Bluetooth module connected to an Arduino to control an LED. See Turning a LED on and off with an Arduino, a HC-06 and Android

A few people have asked how to make it so that the app auto-connect to the Arduino on start up and I thought I would offer my solution. This example adds to the previous guide.

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App Inventor 2 Pseudo Screens

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A!2_Pseudo_Screens_01
As you may have noticed from some of the other posts, I use App Inventor 2 to create Android apps. I do not have time to learn JAVA programming and I found App Inventor an easy way to get in to the world of Android apps. AI2 is not perfect. It is designed as a teaching aid rather than a fully featured Android programming language and as such there are many things missing. However, you can create some surprisingly advanced apps with it. The Arduino Bluetooth Control and the dropController apps were created in AI2 as is the new Bluetooth Control Panel app.

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HC-05 FC-114 and HC-06 FC-114. Part 3 – Master Mode and Auto Connect

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Update 19.09.2015
The FC-114 boards I have have the Bolutek firmware. User DS has reported that he/she has FC-114 boards that have the linvorV1.8 firmware. So if the below does not work for you then check what firmware you have.

I may be missing something but I can not get the HC-05 FC-114 boards in to Master Mode and connect to other BT devices with just AT commands. The modules say they have accepted the commands, such as AT+ROLE1 but when I try to connect to other modules I get the error message “Can only be used in Lord Mode”.

The modules accept “AT+ROLE1” and report they have changed mode but they haven’t really.

In an earlier post I mentioned that it looks likes pin 27 or pin 28 has to be pulled HIGH to enter Master Mode and this does indeed seem to be the case. Everything I have tried without pulling the pin(s) HIGH has failed.

HC-05_FC-114_autoConnectSerialMonitor01
They reply with “OK” and if you interrogate with “AT+ROLE” they report “+ROLE=1” but they are actually still in Slave Mode.

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HC-05 FC-114 and HC-06 FC-114. Part 2 – Basic AT commands

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Update 19.09.2015
The FC-114 boards I have have the Bolutek firmware. User DS has reported that he/she has FC-114 boards that have the linvorV1.8 firmware. So if the below does not work for you then check what firmware you have.

Since the HC-05 FC-114s and the HC-06 FC-11s share the same firmware the following should work on either module.

The default setting on start up is Slave Mode waiting for pairing or a connection and also accepting AT commands. This means it is fairly simply to start using AT commands.

HC-05 FC-114 & HC-06 FC-114_1200

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HC-05 FC-114 and HC-06 FC-114. First Look

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I have just received some new HC-05 and HC-06 Bluetooth modules. These were sold as zs-040s which is the module I actually wanted but I received modules marked FC-114. They share the same breakout board as the zs-040 but have different pins soldered between the Bluetooth module and the breakout board and have a very different firmware.

HC-05_FC-114_&_HC-06_FC-114_001_1600

The small push button switch still has traces to pin 34 and still pulls pin 34 HIGH, however, on the FC-114 boards, pin 34 is a regular IO pin and closing the button switch doesn’t do anything. On the zs-040 boards, closing the button switch and pulling pin 34 HIGH puts the modules in to AT mode. Since the FC-114 starts in AT mode this is no big loss.

It took me a while to figure out the differences.
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HC-05 fs-040 State Pin

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This post follows on from Arduino With HC-05 Bluetooth Module in Slave Mode

The STATE pin on the HC-05 zs050 board is connected to the LED 2 pin on the small bluetooth module and the LED 2 pin is used to indicate when there is an active connection. This means the Arduino can connect to the STATE pin and determine when we have a connection. The STATE pin is LOW when the HC-05 is not connected and HIGH when the HC-05 is connected.

As a quick visual indicator you can put a LED + suitable resistor on the STATE pin. When the module is connected the LED will light.

You can also use the Arduino to read the value of the STATE pin.

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Arduino and Visual Basic Part 3: Controlling an Arduino

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I am still very new to Visual Basic and I have been surprised at how quickly you can develop working apps. My first attempt resulted in a very basic app to receive data from the Arduino which taught me the basics of serial communication in VB. The next step is two way communication and controlling the Arduino from the VB program. I already have a similar project arduinoBTcontrol, where the Arduino is controlled from an Android app over Bluetooth. So all I need do is tweek the Arduino sketch and recreate the Android app in VB.

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