Vivado HLS GPIO switch data for Zybo Board - gpio

Question

I am building a custom IP core in Vivado HLS to run withing image/video processing system that runs in embedded linux on the Zybo board. The core takes image/video data in via and AXI stream, performs a processing task (say Sobel), then outputs this to another AXI stream. This works, however, I'm wishing to use the on board switches for the Zybo to determine which processing task should be ran (default is a passthrough).
I cannot find a resource or simple example that shows (in HLS.. not IP Integrator or the Vivado SDK) how to create a HLS RESOURCE/INTERFACE to read the data from the GPIO switches. What I have is the code below in my top module:
#include <hls_video.h>
#include "ip_types.h"
void MultiImaging(AXI_STREAM& inputStream, AXI_STREAM& outputStream, int rows, int cols, bool sw0, bool sw1)
{
#pragma HLS INTERFACE axis port=inputStream
#pragma HLS INTERFACE axis port=outputStream
#pragma HLS RESOURCE variable=rows core=AXI_SLAVE metadata="-bus_bundle CONTROL_BUS"
#pragma HLS RESOURCE variable=cols core=AXI_SLAVE metadata="-bus_bundle CONTROL_BUS"
#pragma HLS INTERFACE ap_stable port=rows
#pragma HLS INTERFACE ap_stable port=cols
//are these two correct for the switches?
#pragma HLS INTERFACE axis port=sw0
#pragma HLS INTERFACE axis port=sw1
//are these two correct for the switches?
#pragma HLS RESOURCE variable=sw0 core=AXI_SLAVE //GPIO?
#pragma HLS RESOURCE variable=sw1 core=AXI_SLAVE //GPIO?
RGB_IMAGE img(rows, cols);
RGB_IMAGE oimg(rows, cols);
RGB_IMAGE sobel_output(rows,cols);
RGB_IMAGE imgh(rows, cols);
RGB_IMAGE imgv(rows, cols);
RGB_IMAGE hsobel(rows, cols);
RGB_IMAGE vsobel(rows, cols);
GRAY_IMAGE imgGray(rows, cols);
GRAY_IMAGE oimgGray(rows, cols);
#pragma HLS dataflow
hls::AXIvideo2Mat(inputStream, img);
//Passthrough
if(sw1 == 0 && sw0 == 0){
//..code here
}
//Sobel
else if(sw1 == 0 && sw0 == 1){
//..code here
}
//Threshold
else if(sw1 == 1 && sw0 == 0){
//..code here
}
//..etc
}
The above works and gives the proper output for 'C Simulation' and 'C Synthesis.' It errors out in the 'RTL/C Cosimulation' with: "OpenCV Error: Sizes of input arguments do not match." This makes no sense to me since ALL RGB_IMAGES are set initially with the same rows/cols.

Answer 1

Well, the size of the data is NOT done, in this specific case, only by ROWs and COLs.
Try to have a look in your header file, there should be something like:
// typedef video library core structures
typedef hls::stream<ap_axiu<24,1,1,1> > AXI_STREAM;
typedef hls::Scalar<3, unsigned char> RGB_PIXEL;
typedef hls::Mat<MAX_HEIGHT, MAX_WIDTH, HLS_8UC3> RGB_IMAGE;
This is clear because you are using AXI_STREAM. Here you are defining how many bit there are in a pixel, how many channel color in your pixel and so on. If the size of the images is the same, the sentence "Sizes of input arguments do not match" refers to this mismatching problem with the top main function.