Output Toggle

This sample demonstrates how to use the GPIO output function by toggling an LED.

This sample starts with configuring the GPIO as output to drive the LED. The sample then loops while toggling the state of the LED every one-second.

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 to LED0. The LED driver circuit is shown below.

LED Driver Circuit Diagram

Building and Downloading

This sample can be found in the SDK folder:

Keil

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

GCC

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

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

1. Open sample project file.

2. To build the target, follow the steps listed on the Generating App Image in Quick Start.

3. After a successful compilation, the app bin app_MP_xxx.bin will be generated in the directory mdk\bin or gcc\bin.

4. To download app bin into EVB board, follow the steps listed on the MP Tool Download in Quick Start.

5. Press reset button on EVB board and it will start running.

Experimental Verification

1. After resetting the EVB to observe the log messages as shown in the Debug Analyzer.

   Start gpio toggle test!
   

2. Observe that the LED are Blinking.

Code Overview

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

1. Source code directory.

2. Peripheral initialization will be introduced in chapter Initialization.

3. Functional implementation after initialization will be introduced in chapter Functional implementation.

Source Code Directory

1. Project directory: sdk\samples\peripheral\gpio\output_toggle\proj

2. Source code directory: sdk\samples\peripheral\gpio\output_toggle\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:

1. Configure PAD: Set the pin as PINMUX mode, PowerOn, internal Pull-None.

2. Configure PINMUX: Multiplex the pin to GPIO function.

---

driver_gpio_init contains the initialization of the GPIO peripheral.

1. Enable PCC Clock.

2. Set GPIO_Mode to gpio output mode.

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

Functional Implementation

After initialization, the function GPIO_WriteBit() is executed within the while loop to control the GPIO output high and low levels.

while (1)
{
    /* Set GPIO_PIN_OUTPUT */
    GPIO_WriteBit(GPIO_PORT, GPIO_PIN, (BitAction)(1));
    platform_delay_ms(1000);
    /* Reset GPIO_PIN_OUTPUT */
    GPIO_WriteBit(GPIO_PORT, GPIO_PIN, (BitAction)(0));
    platform_delay_ms(1000);
}