Arduino, ESP32/8266, Bluetooth, and stuff
Here we create a basic Classic Bluetooth joypad for use on an Android device to control a microprocessor (Arduino) connected to a Bluetooth module. The app is fairly simply. There are 2 screens; the first is the main control panel and the second is a connection page.
When the CONNECT button on the main screen is clicked the second screen is opened to allow the user to connect to a Bluetooth device. The direction buttons, when clicked, transmit codes to the Arduino.
The HC-05 (ZG-B23090W) uses a regular Bluetooth smd module based on the csr BC417 with a MX 29LV800CBXBI-70G flash memory chip. It appears to be using the HC/Wavesen 2010 firmware and a Google search for “HC-05 2.0-20100601” should give you plenty to read, including some of my older posts.
I have received a few comments about HC-06 and HC-05 modules that use a new breakout board (new to me at least). When I received the first comment I hadn’t seen these modules, by the time I had received the 4th or 5th comment the modules were all over Taobao so I decided to order a few (2 x HC-06 and 2 x HC05). I have no real use for these except to see if they are different to previous versions.
HC-05s are Bluetooth 2.0/2.1 EDR devices that have a serial UART layer on top of the Bluetooth. The UART layer makes them easy to use but hides the Bluetooth functions from the user. This is good if all you want is to make 2 things talk to each other. The HC-05 has two modes of operation; AT command mode and transmission mode. When in AT command mode all data received over the serial UART connection is treated as a command, and when in transmission mode, all data received over the serial UART connection is treated as data.
When in communication mode, if there is an active connection the data is broadcast to the connected device. If not connected, the data, disappears in to some mysterious void.
The HC-05 can operate as either a slave or master device. Slave devices cannot initiate connections, they can only accept them. Master devices can initiate and (depending on the actual module) sometimes accept them. If you want to use the module with a mobile device such as an Android phone, the phone will be the master device and so the HC-05 will need to be the slave. If you want to link two HC-05s, one will need to be a master and the other one a slave.
The HC-06 (ZG-B23090W) uses a regular smd Bluetooth module based on the csr BC417 chip with a MX 29LV800CBXBI-70G flash memory chip. The firmware is well documented and a Google search for “HC-06 linvor V1.8” should get you more than a few hits.
I have received a few comments about HC-06 and HC-05 modules that use a new breakout board (new to me at least). When I received the first comment I hadn’t seen these modules, by the time I had received the 4th or 5th comment the modules were all over Taobao so I decided to order a few (2 x HC-06 and 2 x HC05). I have no real use for these except to see if they are different to previous versions.
The HC-06 is a Bluetooth 2.0/2.1 EDR device that has a serial UART layer on top of the Bluetooth. The UART layer makes them extremely easy to use but hides the Bluetooth functions from the user. This is good if all you want is to make 2 things talk to each other.
The HC-06 has 2 modes of operation; AT mode and transmission mode. When the modules are first powered on they go in to AT mode. Here AT commands can be entered via the wired serial connection. After a connection has been made the modules go in to transmission mode. Here everything the modules receives via the wired serial connection is sent to the connected device. At commands cannot be entered again until the connection is broken.
HC-06s are slave only modules and require a master device to make a connection. Slave devices cannot initiate a connection which means you cannot link 2 HC-06s together. The master module is the HC-05 which can be either slave or master. Since the price for the HC-05 and the HC-06 is basically the same I would suggest buying HC-05s and not HC-06s.
Since writing the below many more modules have been released using the zs-040 breakout boards. Some of the newer ones include modules with a version 3.0-20170601 firmware that work in a slightly different way. I still do not have any of these and so cannot help directly but searching for the firmware should get plenty of hits online and a good place to start is stack overflow and the Arduino forum.
Update 20.07.2017
The zs-040 breakout boards are now being used for many different modules and you may not have the exact same boards as those shown below. The modules I am using here use the EGBT-045MS Bluetooth module and have the HC/Wavesen 2.0-20100601 firmware. They also have an EN pin rather than a KEY pin and they have a small button switch just above the EN pin.
There are now newer zs-040 modules that use the real HC SMD modules, these have a newer firmware and include a blue LED at the top right of the SMD daughter board.
There are also modules that use the same breakout board but have different board markings such as the fc-114 modules:
HC-05 FC-114 and HC-06 FC-114. First Look
HC-05 FC-114 and HC-06 FC-114. Part 2 – Basic AT commands
HC-05 FC-114 and HC-06 FC-114. Part 3 – Master Mode and Auto Connect‘
Updated on 18.07.2015.
Updated 01.12.2016
There are now newer HC-06s and HC-05s that use the zs-040 breakout boards. These new modules have a LED (usually blue) at the top left of the Bluetooth daughter board and have a different firmware to the below. See HC-06 hc01.comV2.0 for an introduction to the HC-06. I haven’t written up details on the HC-05 yet.
Here is the zs-040 version of the popular HC-05. The HC-05 is based on the EGBT-045MS Bluetooth module. It can operate as either a slave device or a master device. As a slave it can only accept connections. As a master it can initiate a connection.
The EGBT-045MS Bluetooth modules (the smaller daughter board) is a 3.3v device. The HC-05 break out board has a 3.3v regulator that allows an input voltage of 3.6v to 6v but the TX and RX pins are still 3.3v. This means you can use the 5V out from the Arduino to power the boards but you cannot connect the Arduino directly to the HC-05 RX pin.
For the HC-05 RX pin (data in) we need to convert the Arduinos 5V to 3.3v. A simple way to do this is by using a voltage divider made from a couple of resistors. In my case I use a 1K ohm resistor and a 2K ohm resistor.
As a quick guide to the voltage divider; 1K + 2K = 3K. 1K is a third of 3K so it reduces the voltage by a third.
One third of 5V is 1.66 and 5-1.66 = 3.33 which is what we want. Putting the resistors the other way would reduce the voltage by 2 thirds.
For more information on voltage dividers have a look at the Sparkfun tutorial
Since the Arduino will accept 3.3 volts as HIGH you can connect the HC-05 TX pin (data out) directly to the Arduino RX pin (The 5V Arduino takes a voltage of 3V or more as HIGH).
In the first part I showed how to control a single LED from an app created in App Inventor. This worked OK but was very limited. You could control only 1 LED and the control was one way; from the app to the Arduino. What if you want to have 2 way control of the LED and to be able to also control the LED from the Arduino side? What if you want to control more than 1 LED?
In this guide we look at adding two-way communication. Here we control an LED but you could have it doing anything.
In first example you could only control the LED from the Android app, here we extend the example so that we can also control the LED at the Arduino side. When the LED is turned on or off by the Arduino we want the button in the app to update to show the correct LED status.
The first example used methods only suitable for controlling one LED, this time we will try to make it so the Arduino sketch and also the AI2 app can be easily scaled and so once you have the basic app in place adding extra buttons and controls should be fairly straight forward.