From shallow to deep, Bluetooth 4.0/BLE protocol stack development strategy (2)

This series of tutorials will be combined with TI's CC254x SoC series to explain the development process of Bluetooth 4.0 from the construction of the environment to the development of the Bluetooth 4.0 protocol stack. The tutorial is divided into six parts, this article is the second part:
      

The second part of the knowledge points:

The sixth section of the independent button query method

Section 7 Interrupt Mode of Independent Buttons

Section VIII CC254x internal temperature sensor temperature acquisition

Section IX five-way button

Section 10 Buzzer

For an introduction to TI's CC254x chip, you can click on the link below to view:

Mainstream Bluetooth BLE control chip detailed (1): TI CC2540

Recommended in the same series:

From shallow to deep, Bluetooth 4.0/BLE protocol stack development strategy (1)

For the download of the tool for this article, you can go to the following address:

The sixth section of the independent button query method

There is a separate button KEY1 on the MT254xboard, as shown in the figure, the independent button and the reset button are in the upper left corner of the entire team. The button is connected to the CPU through the P0.0 port. It is high when there is no button and low when pressed. Below we use the LCD to display the status of the individual buttons.

The corresponding schematic diagram is as follows:

We first read the state of the button by query. Because the button is connected to the P0.0 port, we can know the state of the button by reading the level of the P0.0 port.

Uint8 KeyValue(void) // Read button status

{

If((P0&0X01) == 0X00 ) // Press low

{

Return KEY_DOWN;

}

Else

{

Return KEY_UP;

}

}

Here we constantly read the state of the button in the while loop, and judge whether it changes, if it changes, change the display of the LCD.

Int main(void)

{

Uint8 OldKeyValue = 0;

Uint8 NewKeyValue = 0;

SysStartXOSC();

LCD12864_Init();

LCD12864_DisStr(1, “Key Test”);

// button initialization

P0SEL &= ~0X01; // Set to IO function

P0DIR &= ~0X01; // Set as input function

While(1)

{

NewKeyValue = KeyValue(); // Read button status

If(OldKeyValue != NewKeyValue) // button status change

{

OldKeyValue = NewKeyValue; // save the current button state

If(OldKeyValue == KEY_DOWN)

{

LCD12864_DisStr(3, “Key Down ”);

}

Else

{

LCD12864_DisStr(3, “Key Up ”);

}

}

}

Return 0;

}

Run the program, the effect is as shown:

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