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Forming

The module <BCM2835> of subsystem "Data Acquisition"

Introduction

The module provides OpenSCADA system with the support data sources of realtime, which based on Raspberry PI board's General Purpose Input/Output (GPIO) grounded on BCM2835 chip. The BCM2835 GPIO of Raspberry Pi counts 32 pins in maximum some from its can also performs alternative functions like: I2C, UART, SPIO and etc. For access to the GPIO in general functions there is used a library libBCM2835.

1. Controller object

GPIO into OpenSCADA configured with new controller object creation (Fig.1), the container parameters' objects — a single parameter of the board's GPIO.

Fig.1. Configuration tab of the controller object.

From this tab you can set:

• The state of the controller, as follows: Status, "Enable", "Run" and the name of the database containing the configuration.
• Id, name and description of the controller.
• The state, in which the controller must be translated at boot: "To enable" and "To start".
• Name of table to store the configuration of the parameters of the controller.

2. The controller's parameter object

The parameter object is a direct representative-reflection for the GPIO, which contained attributes set with Boolean types and it whole quantity 32. Parameter's object configuration tab is shown in Figure 2. The acquisition data is done only in synchronous mode but GPIO must be fast.

Fig.2. Parameter's object configuration tab — DAQ board.

With the parameter's object configuration tab you can set:

• The state of the parameter: type, "Enable" and static functions list.
• Id, name and description of the parameter.
• The state, in which the parameter must be translated at boot: "To enable".

Tab "Attributes" for the GPIO is shown in Figure 3. For the GPIO there is accessed also "Configuration" tab (Fig.4) with IO mode and reverse state.

Fig.3. Tab "Attributes" of the parameter object.

Fig.4. Tab "Configuration" of the parameter object.

For maximum fast access to the GPIO the parameter object provides three static functions: "mode", "get" and "put". These functions can be used in an user programming area of OpenSCADA system for the organization of not ordinary interaction algorithms. To address the functions you can use static call address "BCM2835.{cntr}.{prm}.{Func}()" or dynamic "SYS.DAQ.BCM2835.{cntr}.{prm}["{Func}"].call()". Where:

• {cntr} — identifier of the controller's object;
• {prm} — identifier of the parameter's object;
• {Func} — identifier of the function.

2.1. Function GPIO: Mode (mode)

Description: GPIO mode, input or output.
Parameters:

2.2. Function GPIO: Get (get)

Description: GPIO get pin level.
Parameters:

2.3. Function GPIO: Put (put)

Description: GPIO put pin level.
Parameters:

3. Notes

The module tested on boards Raspberry Pi 2, 3 model B, for this details you can see to the page and the task.

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