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For prototyping and testing, a module that is already soldered was used, as it
was a simplified method to connect to the device and observe if the module is
receiving the information from the Android device. When the module was
integrated onto the PCB, a non-soldered HC-05 was used to solder the
connections on to the assigned pins, as it is more effective in looking more
presentable and it conserves a little more space. The HC-05 module actually is
directly connected to the board instead of having an abundant amount of wiring
polluting inside the Puppy Pal’s infrastructure.
The HC-05 is configured to be interfaced to the system, in order to configure
certain modes, the module uses AT Commands. To configure AT commands, the
device was needed to communicate via serial connections with the MCU and a
computer using a serial communication software such as HyperTerminal. Since
the Arduino UNO was used for prototyping and testing, configuring the module in
the Arduino IDE was used. The Arduino IDE comes with an embedded serial
UART functionality. The AT commands will be used to primarily to display the
specifications of the device and to change the specifications, if it is needed.
Table 4.7 provides simple AT commands that were used to set and/or check
certain specs. An AT command that was very significant is finding the MAC
address of the module, the MAC address is needed to interface precisely to the
Android application. Another AT command that was needed is determining the
baud rate or changing the baud rate. This is needed to interface with the
microcontroller, and a baud rate of 9600 was used, which is usually a typical
baud rate that is used for MCU applications. In addition, to retrieve some sort of
connectivity to the Bluetooth module from the Android device, the mobile Android
device needed the password and name of the Bluetooth module. As there is an
AT command to get the password and name of the module. An AT command is
needed to check if the device is configured as a slave or a master device. Also
an AT command to change the device to a slave if it is originally configured as a
master device may be needed. If the module may somehow get corrupted and
will need to reset to its default setting, an AT command restoring to the original
setting may be potentially needed. When the module is configured to reset, it
sets the pin code back to “1234” and baud rate back to 38400 bps. Under some
system debugging circumstances, the firmware version may be needed to view if
the Android device will be able to connect to the module. To check the state of
the module is a significant aspect of making sure configuring to the Android
device is done correctly.
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