KeyScan in Active Mode

This sample code guide is designed to help users easily and comprehensively understand KeyScan sample. This sample demonstrates how KeyScan works in active mode.

Requirements

For hardware requirements, please refer to the Requirements.

Wiring

The EVB is connected to a matrix keyboard module, connect P0_2 to ROW0, P0_3 to ROW1, P0_0 to COLUMN0, and P0_1 to COLUMN1. The hardware connection of KeyScan sample code is shown in the figure below.

../../../_images/KeyScan_Sample_Code_Hardware_Connection_Diagram.png — KeyScan Sample Code Hardware Connection Diagram

Configurations

The following macros can be configured to modify pin definitions.
- #define COLUMN0 ADC_0
- #define COLUMN1 ADC_1
- #define ROW0 ADC_2
- #define ROW1 ADC_3
The entry function is as follows, call this function in main() to run this sample code. For more details, please refer to the Initialization.
```
keyscan_demo();
```

Building and Downloading

For building and downloading, please refer to the Building and Downloading.

Experimental Verification

Press the Reset button on the EVB, when keys are pressed, KeyScan starts scan. After the scan ends, it enters the KeyScan interrupt and prints the key information.
```
io_demo_task: pKeyData->key[xx] xx
```
After all the keys are released, print the following log.
```
io_demo_task: All key release
```

Code Overview

This section introduces the code and process description for initialization and corresponding function implementation in the sample.

Source Code Directory

For project directory, please refer to Source Code Directory.
Source code directory: sdk\src\sample\io_demo\keyscan\active\keyscan_demo.c.

Initialization

The initialization flow for peripherals can refer to Initialization Flow.

KeyScan initialization flow is shown in the following figure.

../../../_images/KEYSCAN_Initialization_Flow_Chart.png — KeyScan Initialization Flow Chart

Call Pad_Config() and Pinmux_Config() to initialize the pin.

static void board_keyscan_init(void)
{
   Pad_Config(COLUMN0, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_ENABLE, PAD_OUT_LOW);
   Pad_Config(COLUMN1, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_ENABLE, PAD_OUT_LOW);
   Pad_Config(ROW0, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_LOW);
   Pad_Config(ROW1, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_LOW);

   Pinmux_Config(COLUMN0, KEY_COL_0);
   Pinmux_Config(COLUMN1, KEY_COL_1);
   Pinmux_Config(ROW0, KEY_ROW_0);
   Pinmux_Config(ROW1, KEY_ROW_1);
}

Call RCC_PeriphClockCmd() to enable the KeyScan clock and function.

Initialize the KeyScan peripheral:

Define the KEYSCAN_InitTypeDef type KeyScan_InitStruct, and call KeyScan_StructInit() to pre-fill KeyScan_InitStruct with default values.
Modify the KeyScan_InitStruct parameters as needed. The KeyScan initialization parameter configuration is shown in the table below.
Call KeyScan_Init() to initialize the KeyScan peripheral.

KeyScan Initialization Parameters
KeyScan Hardware Parameters	Setting in the `KeyScan_InitStruct`	KeyScan
Column Size	`KEYSCAN_InitTypeDef::colSize`	2
Row Size	`KEYSCAN_InitTypeDef::rowSize`	2
Scan Interval	`KEYSCAN_InitTypeDef::scanInterval`	0x80

Call KeyScan_INTConfig() to enable the KeyScan scan end interrupt KEYSCAN_INT_SCAN_END and the KeyScan all release interrupt KEYSCAN_INT_ALL_RELEASE.
Call NVIC_Init() to enable NVIC of KeyScan.
Call KeyScan_Cmd() to enable KeyScan.

Functional Implementation

Interrupt Handle

After the scan key matrix is completed, the KeyScan scan end interrupt is triggered.
1. Call KeyScan_GetFlagState() to check KEYSCAN_INT_FLAG_SCAN_END interrupt flag state.
2. Call KeyScan_INTMask() to mask KEYSCAN_INT_SCAN_END interrupt.
3. Call KeyScan_GetFlagState() to check the FIFO empty flag state, if KEYSCAN_FLAG_EMPTY flag is set:
  1. Call KeyScan_GetFifoDataNum() to get KeyScan FIFO data number.
  2. Call KeyScan_Read() to read data from KeyScan FIFO.
  3. If new buttons are pressed:
    1. Send a message to the task, and after the task receives the message, it will print log.
    2. Call KeyScan_ClearINTPendingBit() to clear KEYSCAN_INT_SCAN_END interrupt.
    3. Call KeyScan_INTMask() to unmask KEYSCAN_INT_SCAN_END interrupt.
  4. If no new buttons are pressed:
    1. Call KeyScan_ClearINTPendingBit() to clear KEYSCAN_INT_SCAN_END interrupt.
    2. Call KeyScan_INTMask() to unmask KEYSCAN_INT_SCAN_END interrupt.
When the release time count reaches the set value, if no key is pressed, the KeyScan all release interrupt is triggered.
1. Call KeyScan_GetFlagState() to check KEYSCAN_INT_FLAG_ALL_RELEASE interrupt flag state.
2. Call KeyScan_INTMask() to mask KEYSCAN_INT_ALL_RELEASE interrupt.
3. Send a message to the task, and after the task receives the message, it will print log.
4. Call KeyScan_ClearINTPendingBit() to clear KEYSCAN_INT_ALL_RELEASE interrupt.
5. Call KeyScan_INTMask() to unmask KEYSCAN_INT_ALL_RELEASE interrupt.