Input Polling

This sample uses the GPIO input function to detect the GPIO input signal by polling.

This sample starts with configuring the GPIO as input to detect changes in the GPIO input. Then it loops while printing information about the GPIO input.

Requirements

The sample supports the following development kits:

Development Kits
Hardware Platforms	Board Name
RTL87x2G HDK	RTL87x2G EVB

For more requirements, please refer to Quick Start.

Wiring

Connect P1_0 and VDDIO to detect input high level. Connect P1_0 and GND to detect input low level.

Note

The VDDIO can be connected by referring to the instructions for IC Power Voltage Selection in EVB Guide .

Building and Downloading

This sample can be found in the SDK folder:

Keil

Project file: samples\peripheral\gpio\input_polling\proj\rtl87x2g\mdk

GCC

Project file: samples\peripheral\gpio\input_polling\proj\rtl87x2g\gcc

To build and run the sample, follow the steps listed below:

Open sample project file.
To build the target, follow the steps listed on the Generating App Image in Quick Start.
After a successful compilation, the app bin app_MP_xxx.bin will be generated in the directory mdk\bin or gcc\bin.
To download app bin into EVB board, follow the steps listed on the MP Tool Download in Quick Start.
Press reset button on EVB board and it will start running.

Experimental Verification

After resetting the EVB, observe the log messages as shown in the Debug Analyzer.
```
Start input polling test!
```
When a high level input is detected, the following message is printed in the Debug Analyzer every 2 seconds.
```
gpio_input_data = 1
gpio_input_data = 1
gpio_input_data = 1
...
```
When a low level input is detected, the following message is printed in the Debug Analyzer every 2 seconds.
```
gpio_input_data = 0
gpio_input_data = 0
gpio_input_data = 0
...
```

Code Overview

This chapter will be introduced according to the following several parts:

Source code directory.
Peripheral initialization will be introduced in chapter Initialization.
Functional implementation after initialization will be introduced in chapter Functional implementation.

Source Code Directory

Project directory: sdk\samples\peripheral\gpio\input_polling\proj
Source code directory: sdk\samples\peripheral\gpio\input_polling\src

Source files are currently categorized into several groups as below.

└── Project: output_toggle
    └── secure_only_app
        └── Device                   includes startup code
            ├── startup_rtl.c
            └── system_rtl.c
        ├── CMSIS                    includes CMSIS header files
        ├── CMSE Library             Non-secure callable lib
        ├── lib                      includes all binary symbol files that user application is built on
            └── rtl87x2g_io.lib
        ├── peripheral               includes all peripheral drivers and module code used by the application
            ├── rtl_gpio.c
            ├── rtl_pinmux.c
            └── rtl_rcc.c
        └── APP                      includes the ble_peripheral user application implementation
            ├── io_gpio.c
            └── main_ns.c

Initialization

The initialization process includes board_gpio_init and driver_gpio_init.

board_gpio_init contains the PAD and PINMUX settings:

Configure PAD: Set the pin to PINMUX mode, PowerOn, internal Pull-Up.
Configure PINMUX: Multiplex the pin to GPIO function.

driver_gpio_init contains the initialization of the GPIO peripheral.

Enable PCC Clock.
Set GPIO_Mode to GPIO input mode.

RCC_PeriphClockCmd(APBPERIPH_GPIO, APBPERIPH_GPIO_CLOCK, ENABLE);
...
GPIO_InitStruct.GPIO_Mode   = GPIO_MODE_IN;

Functional Implementation

After initialization, the function GPIO_ReadInputDataBit() is executed within the while loop and prints the GPIO input level information.

while (1)
{
   uint8_t gpio_input_data = GPIO_ReadInputDataBit(GPIO_PORT, GPIO_PIN);
   DBG_DIRECT("gpio_input_data = %d", gpio_input_data);
   platform_delay_ms(2000);
}