Libpixyusb2 and callChirp Reference

josejacomeb · July 20, 2018, 6:56pm

Hi to all,

I’ve received my new Pixycam2, it’s a great product, with an interesting build-in functions…

However, I would like to program the camera from myself to try some different applications. I read about the cool library libpixyusb2 for interact with the device, but unfortunately I haven’t found a program reference like in the last PixyCam, I reviewed the examples but I think it is still enough info unavailable(Also I saw there are recent commits in Github). So, there are my questions…

Is there available any reference of the library libpixyusb2? (I also tried to build Doxygen doc)
Is there any reference for arguments to callChirp(I saw examples about getting image of the Camera with cam_getFrame)

Greetings,

José

edge · July 20, 2018, 11:08pm

Hello Jose,
We have this information:
https://docs.pixycam.com/wiki/doku.php?id=wiki:v2:building_the_libpixyusb_example_on_linux

What are you trying to do? Perhaps we can point you in the right direction.

Edward

josejacomeb · July 23, 2018, 4:36am

Hi Edward,

I would like to save images in a Webserver, when an action is performed(Ex. A new color detected), now I have a working Node.JS server with a C++ Client to send and show images in a webpage.

So, in that way I will have a registry of actions in my web page, well so I have tried some “functional” examples to get images from the Pixycam2 through callChirp but unfortunately the code response me a -3 parsing error… Well it’s my idea, so I appreciate to have the new reference for getImage

Cheers

edge · July 23, 2018, 1:08pm

Hello Jose,
I’ll pass this on to our development team.

This code snippet below will get a frame. Hope it helps!

Edward

int32_t response;
uint32_t fourcc;
int8_t renderflags;
uint16_t width, height;
uint32_t numPixels;
uint8_t frame[316*208];

return_value = pixy.callChirp(“cam_getFrame”, // String id for remote procedure
1,0x21, // mode
2, 0, // xoffset
2, 0, // yoffset
2, 316, // width
2, 208, // height
0, // separator
&response, // pointer to mem address for return value
&fourcc,
&renderflags,
&width,
&height,
&numPixels,
&frame, // pointer to mem address for returned frame
0);

josejacomeb · July 23, 2018, 5:23pm

Hi, Edge…

Thanks for your response, I’ve tried that code, but unfortunately I’ve got a -3(Chirp Parse Error) as a response.

I noticed that in Pixymon -> View -> Console I can get the “reference” of the function cam_getFrame(), it is

help cam_getFrame
> cam_getFrame(INT8 mode, INT16 xOffset, INT16 yOffset, INT16 width, INT16 height)
Get a frame from the camera
Parameters:
   mode: one of the following CAM_GRAB_M0R0 (0x00), CAM_GRAB_M1R1 (0x11), CAM_GRAB_M1R2 (0x21)
   xOffset: x offset counting from left
   yOffset: y offset counting from top
   width: width of frame
   height: height of frame
Returns:
   0 if success, negative if error
   BA81 formatted data

So I format the command callChirp() as you can see in the reference, whatever, I still getting the same error, I think that I’m bad formatting my callChirp arguments due my code is stuck on Chirp::loadArgs library…

How can I debug that args to get the image?

#include "libpixyusb2.h"

using namespace std;

void errores(int resultado, String proceso) {
    if (resultado == PIXY_RESULT_OK) cout << proceso << " Comando finalizado satisfactoriamente " << resultado << endl;
    else if (resultado == PIXY_RESULT_ERROR) cout << proceso << " Comando con error de resultado " << resultado << endl;
    else if (resultado == CRP_RES_ERROR_CRC) cout << proceso << " Error CRC " << resultado << endl;
    else if (resultado == CRP_RES_ERROR_PARSE) cout << proceso << " Parse error " << resultado << endl;
    else if (resultado == PIXY_RESULT_ERROR) cout << proceso << " Comando sin respuesta " << resultado << endl;
    else if (resultado == PIXY_RESULT_BUTTON_OVERRIDE) cout << proceso << " Comando, buscando override" << resultado << endl;

}


Pixy2 camarapixy;
int estadopixy = 0;
int Result;

int main(int argc, char** argv) {

    uint8_t Purple_Color = 0xFF;
    uint8_t Green_Color = 0x00;
    uint32_t Color;
    Color = (Purple_Color << 16) + (Green_Color << 8) + Purple_Color;

    estadopixy = camarapixy.init();
    if (estadopixy) {
        cout << "Error de conexion con Pixy, seguro que esta conectada?" << endl;
        return -1;
    }

    //cout << "Version: " << camarapixy->version << std::endl;

    int return_value = camarapixy.m_link.callChirp("led_set", INT32(Color), END_OUT_ARGS, &Result, END_IN_ARGS);
    errores(return_value, "Led_set");
    int32_t response;
    uint32_t fourcc;
    int8_t renderflags;
    uint16_t width, height;
    uint32_t numPixels;
    uint8_t frame[316 * 208];
    return_value = camarapixy.m_link.callChirp("cam_getFrame", // String id for remote procedure
            INT8(0x21), // mode
            INT16(0), // xoffset
            INT16(0), // yoffset
            INT16(316), // width
            INT16(208), // height
            END_OUT_ARGS,
            &response, // pointer to mem address for return value
            &fourcc,
            &renderflags,
            &width,
            &height,
            &numPixels,
            &frame//z, // pointer to mem address for returned frame
            //END_IN_ARGS
            );
    errores(return_value, "cam_getFrame");
    cout << "Respuesta camara: " << response << endl;
    cout << "Codec FourCC: " << fourcc << endl;
    cout << "Render flags: " << renderflags << endl;
    cout << "width: " << width << endl;
    cout << "height: " << height << endl;
    cout << "Numero Pixeles: " << numPixels << endl;
    cout << "Captura: " << frame << endl;
    return_value = camarapixy.m_link.callChirp("cam_getFrame", // String id for remote procedure
            1, 0x21, // mode
            2, 0, // xoffset
            2, 0, // yoffset
            2, 316, // width
            2, 208, // height
            0, // separator
            &response, // pointer to mem address for return value
            &fourcc,
            &renderflags,
            &width,
            &height,
            &numPixels,
            &frame, // pointer to mem address for returned frame
            0);
    errores(return_value, "cam_getFrame");
    return_value = camarapixy.m_link.callChirp("version");
    errores(return_value, "Version");
    return_value = camarapixy.m_link.callChirp("led_setRGB", INT8(55), INT8(125), INT8(255));
    errores(return_value, "led_setRGB");
    sleep(3);
    return_value = camarapixy.m_link.callChirp("led_setRGB", INT8(255), INT8(125), INT8(5));
    errores(return_value, "led_set_RGB");
    sleep(3);
    return 0;
}

Response

Led_set Comando finalizado satisfactoriamente 0
cam_getFrame Parse error -3
Respuesta camara: -1
Codec FourCC: 0
Render flags: 
width: 0
height: 0
Numero Pixeles: 0
Captura: 
cam_getFrame Parse error -3
Version Parse error -3
led_setRGB Parse error -3
led_set_RGB Parse error -3

edge · July 24, 2018, 3:31pm

One thing I noticed is that you didn’t terminate your first call with a 0, or END_IN_ARGS

There may be a parse error (which may indeed be a bug), but I’m curious – it may still return the data.

Edward

josejacomeb · July 25, 2018, 7:17pm

Edward,

Thanks for response, I’ve terminated all my calls with END_IN_ARGS, like I show below, in the “working example”

return_value = camarapixy.m_link.callChirp("cam_getFrame", // String id for remote procedure
            INT8(0x21), // mode
            INT16(0), // xoffset
            INT16(0), // yoffset
            INT16(316), // width
            INT16(208), // height
            END_OUT_ARGS,
            &response, // pointer to mem address for return value
            &fourcc,
            &renderflags,
            &width,
            &height,
            &numPixels,
            &frame, // pointer to mem address for returned frame
            END_IN_ARGS
            );

and in your code

    return_value = camarapixy.m_link.callChirp("cam_getFrame", // String id for remote procedure
            1, 0x21, // mode
            2, 0, // xoffset
            2, 0, // yoffset
            2, 316, // width
            2, 208, // height
            END_OUT_ARGS, // separator
            &response, // pointer to mem address for return value
            &fourcc,
            &renderflags,
            &width,
            &height,
            &numPixels,
            &frame, // pointer to mem address for returned frame
            END_IN_ARGS);

But it still give me a parse error, I searched more deep and I found that I fails in the function int Chirp::loadArgs(va_list *args, void *recvArgs[]) especifically in

    // check to see if last arg is NULL, if not, we have a parse error
    // if the arg isn't null, it means the caller is expecting data to be
    // put there.  If data isn't put there, and the caller dereferences, segfault
    if (va_arg(*args, void **) != NULL) {
        return CRP_RES_ERROR_PARSE;
    }

It’s possible that we miss some value in callChirp()?

José

edge · July 25, 2018, 8:46pm

Hello Jose,
I will log this as a bug so that a developer will look into it. I don’t have an accurate timeframe for when this will be examimined/fixed. My apologies…

Edward

jimmy · September 6, 2018, 2:27am

Hi Edwar,

I got the same issue using F/W:3.0.10 with libPixyUSB2
the “cam_getFrame” always return -3 when trying above examples…

Any fixing/workaround information available yet?

Best Regards,

Jimmy

edge · September 6, 2018, 3:15pm

Hello Jimmy,
We are working on the next version of firmware – hopefully release in the next couple weeks.

Edward

jimmy · September 7, 2018, 9:39am

Thank you very much!

edge · September 28, 2018, 8:35pm

Hello Jimmy,
Our new release should resolve your issue. Please check our blog for some details about the latest release:

https://pixycam.com/blog/

Edward