Scale

This sample demonstrates the scale function of PPE peripheral.

Requirements

The sample supports the following development kits:

Development Kit
Hardware Platforms	Board Name
RTL87x2G HDK	RTL87x2G EVB

For more requirements, please refer to Quick Start.

Wiring

None

Building and Downloading

This sample can be found in the SDK folder:

Keil

Project file: samples\peripheral\ppe\scale\proj\rtl87x2g\mdk

GCC

Project file: samples\peripheral\ppe\scale\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.
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 the sample is executed, observing the following log in the DebugAnalyzer window indicates successful scaling:

PPE scale test passed 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\ppe\scale\proj
Source code directory: sdk\samples\peripheral\ppe\scale\src

Source files are currently categorized into several groups as below.

└── Project: decompress
    └── ppe
        ├── config                   includes project construct configuration
        ├── display                  includes the peripheral drivers related with display
        └── 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
        ├── peripheral               includes all peripheral drivers and module code used by the application
        └── APP                      source code of PPE scale sample
            ├── main_ns.c
            └── ppe_test.c

Initialization

The initialization process is included in PPE_scale_test().

Initialize data of image to be scaled and output buffer.
Initialize PPE structures that contain information of image and output.

source.address = (uint32_t)pic_data;
source.memory = (uint32_t *)pic_data;
source.color_key_en = DISABLE;
source.color_key_value = 0;
source.format = PPE_RGB888;
source.width = 25;
source.height = 25;

target.address = (uint32_t) target_buf;
target.memory = (uint32_t *) target_buf;
target.color_key_en = DISABLE;
target.color_key_value = 0;
target.format = PPE_RGB888;

After determining the scale ratio of the input image, invoke PPE_Scale() to start PPE scaling. The scale ratio is assigned as 2 on both x and y coordinates in the following example:

PPE_ERR err = PPE_Scale(&source, &target, 2, 2);

Tip

About the correctness of the scaling result, refer to Troubleshooting

Functional Implementation

While running PPE_Scale(), data will be filled in the output buffer pixel by pixel. When this function has finished executing, it indicates PPE has also finished its work to scale.

Troubleshooting

Correctness Check

After PPE_Scale() has finished, the output buffer will be compared with golden data. If any error occurs, the following log will be displayed in the DebugAnalyzer Tool:

PPE scale error

And also, the error code will be printed on the last line with the following log:

PPE scale test passed ‘error code’