The latest Bluetooth 4.2 low power (BLE), also known as Bluetooth intelligence, is designed for the Internet of Things (IOT). Each primary operating system has made the development of Bluetooth technology makes the development of mobile applications simple.
Using the PSoC Creator 3.2, XCODE 6, and SWIFT applications development environments, you can develop an app to process simple remote control using iPhone, demonstrating using GATT configuration files and GAP peripherals in embedded BLE system development. The car consists of two motors and a PSOC4200 BLE device of the H-bridge with an orthogonal encoder and the PSOC4200 BLE device of Cypress Semiconductor.
Figure 1: PSOC4200 From Cypress Semiconductor can use Bluetooth low power consumption 4.2 to control robot cars.
The project begins with a simple LED and touchpad control, indicating the connection status. The initial Capsense slider is used to control the red LED, when the board is not connected, the blue LED is used for blue LEDs.
To create a new project for PSoC4100 Ble, you can add components to the simple schematic. The BLE component is added to the graphics design tool and links to the Capsense component. PWM is required to drive the LED, and because the blue LED is valid for the low level, it is necessary to reverse the PWM, so the library uses a non-door.
PWM configuration needs to be single output and requires clock components in the library. For flashing LEDs, the clock is configured to 1 kHz. Reset is connected to the logic low (because it is highly valid), changing the name of the PWM makes it easier to connect. The project adds a linear slider to process five sensors on the evaluation board.
Configure the BLE component in the schematic diagram to customize the configuration file, and the board acts as a GATT server with a GAP (General Access Profile) peripheral device. The iPhone is a GAP Central communication with a board that is connected as a GAP peripheral.
The GATT server is a database on the BLE to store information shared with the iPhone as a GATT client.
Customizing profiles are essentially a custom service to create a GATT database, create a custom service of LED and Capsense; these have UUID (unique ID) so that the iPhone can find this service. This allows the firmware to communicate with the service. 1 byte LED profile indicates that the LED state can be written and read, so you need to activate the read and write flags. Capsense features (no symbol 16 2 byte format) can only be read and cannot be written remotely. In order to obtain a notification, the notification mark is activated. Customer readable notifications can be added at this time.
Each feature requires a 128-bit UUID, while the Creator tool provides a default value for the minimum valid bits can be modified.
GAP settings include device names and advertising settings. In this example, it is not advertised by closing the timeout. In the ad bags for once every 20 to 30 milliseconds, some information can help identify devices, such as the name of the device, and available services.
After setting Ble, Capsense, PWM, and LED, you need to set the pin. The first pin to set is the PIN0 modulation capacitor of the Capsense port 4. The Capsense slider is then connected to the P21 to P25 pins on the board. Blue LED connects to Port3 PIN7, Red LEDs to PORT2, PIN6. The tool is then automatically generated for the firmware.
firmware
Using Xcode implements firmware in the GitHub project, the first variable is an unsigned global variable indicating the LED state, and the second variable is a Capsense notification.
The UPDATE_LED function updates the GATT database using the current status of the LED. If BLE (from getState functions) is connected, Cyble_LeDCapsense_led_char_handle reads the value of the pin and reverse it at the LED. Use the GATT WRITEATTRIBUTE function to write 1 bytes to the database. This can be called anywhere in the source code to read the status of the LED.
The next function is the same as Capsense. This will enter the GATT database using a cyble_ledcapsense_capsesne_char_handle and 2 byte values. This also uses the NOTIFY function in the BLE, so the notification is automatically sent when the CapSenseNotify variable changes.
Next is the BLE event handler. This will process all events from the BLE, such as stacks open or disconnect. This uses a blue LED display connection that is happening or being closed, so these calls trigger PWM and update the GATT database using the LED status and CapSense values. This is automatically handled by the stack firmware.
The next event is a write event that calls the event when the remote end wants to write to the GATT database. Here, the stack gives the features that need to be written.
You can then compile all of this for the device using Xcode.
robot
The construction of the car itself is relatively simple because two motors are connected to the H bridge, which is mapped to the continuous pin on the board. The switch on the device is displayed in the application, and the speed of each motor can be controlled by the application to guide the car.
Figure 2: Robot board combines BLE chip, two wheels and a h bridge.
There are four key features, and the rotational speed of the left and right motors use the orthogonal encoder, two PWM drive two motors. Two switches on the iPhone can quickly switch characteristics to zero.
The schematic is a similar element with the initial LED project. PWM is simple, the cycle is 100, compared to 50, the duty cycle is 100, which is 0 to 100 ratios in the iPhone. The orthogonal encoder uses TCPWM, which can decode each of the orthogonal signals from the left and right pulses in 1x mode, thereby calculating the pulse rather than the frontier and falling edges.
The PSoC pin is sufficient to power the H bridge, and the other pin is a software control switch, and the direction of the motor is controlled by the software. The last one is a PWM for the LED connection.
The orthogonal encoder is 64 pulses per revolution, and every 187 ms triggers an interrupt to find the number of pulses that has occurred and zoomed to give the RPM number.
Custom Motor_Service configuration file has four features, namely 8-bit integers, writable, from -100 to +100, speed left, and speed. This also includes humans readable forms and notices. This updates the GATT database and issues notifications.
Ble is a peripheral device with a Robot and motor service UUID name. This simplifies the connection process.
The firmware is generated from the tool, including the notification mark, left and right speed count, and left and right speeds. The ISR is triggered each time the board button is turned off, and the speed is stored in the GATT database.
The next step is to link firmware to a smartphone application.
Build an application
Build an iOS app in SWIFT has two view controllers in the Cypress College. The first is a table view controller, which displays all the devices that the phone can see. When this class is started, it will relay all the devices that match the service you hear. In this case, there is only one remote control car, so there is only one thing in the table, but this can be used to control many peripherals.
The second view controller itself is a remote control. This uses two labels for the left and right speed meters, and two switches are used on the left and right motors. For left and right motors, the selector view ranges from -100 to +100.
There are three classes of this model:
Rccar.swift, it tracks the connection and speed of the left and right motors;
Tracking equipment Bt.neighborhood class.
The BLE connection class handles the connection so that the RC object has the neighborhood and connection associated therewith. This class records its fact that it is interested in and sets the selector to two sliders.
The last thing happening is that if the speedometer is updated, it will update the left and right text values on the screen. Before the view disappears, disable your device and connection when you press the back button. These are connected to the firmware through the application programming interface (API) in SWIFT.
in conclusion
The latest Bluetooth low power consumption in the PSoC 4100 device 4.2 technology and simple H bridge, motor and encoders make simple iPhone applications easy to develop. Using the latest version of PSoC Creator, Xcode and Swift development tools allow developers to create schematics, firmware, and applications for robots. Read more
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