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W_Schauberg
Joined: 17 Sep 2009
Posts: 16
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| PCD: USB HID example and data transfer |
 Posted: Tue Dec 01, 2009 6:39 am |
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I'm using one code that is mostly based on EX_USB_HID.c file.
The connection with PC - and my device is working fine, but i have one problem.
I need to receive over 1MB of different data types from PC.
The data has different length and type.
If i want to be able to receive all this data, what should i do ?
How to organize all this ? |
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epitalon
Guest
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| Posted: Tue Dec 01, 2009 1:16 pm |
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Your question is not very clear ...
If, by "datatype", you refer to report configuration that you must set into the class specific (hid) descriptor,
don't take the pain to describe all your data, their size, their minimum and maximum values, and so on...
Just describe a generic report with :
report size : 8 bits
report count : the number of bytes you need to send at a time
usage minimum : 0
usage maximum : 0xFF |
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W_Schauberg
Joined: 17 Sep 2009
Posts: 16
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| Posted: Wed Dec 02, 2009 2:14 pm |
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Thank you for your reply epitalon!
Anti aging ? :-)
Back to the question....
| Code: | #define USB_CONFIG_HID_TX_SIZE 2
#define USB_CONFIG_HID_RX_SIZE 2
#include <pic24_usb.h> //Microchip PIC24 hardware layer for usb.c
#include <usb_desc_hid.h> //USB Configuration and Device descriptors for this UBS device
#include <usb.c> //handles usb setup tokens and get descriptor reports
....
usb_init_cs();
usb_task();
usb_debug_task();
if (usb_enumerated())
{
if (!send_timer)
{
send_timer=250;
out_data[0]=read_adc();
out_data[1]= 1; //BUTTON_PRESSED();
if (usb_put_packet(1, out_data, 2, USB_DTS_TOGGLE));
// printf("\r\n<-- Sending 2 bytes: 0x%X 0x%X", out_data[0], out_data[1]);
}
if (usb_kbhit(1))
{
usb_get_packet(1, in_data, 2);
//printf("\r\n--> Received data: 0x%X 0x%X",in_data[0],in_data[1]);
//if (in_data[0]) {LED_ON(LED2);} else {LED_OFF(LED2);}
//if (in_data[1]) {LED_ON(LED3);} else {LED_OFF(LED3);}
}
// send_timer--;
// delay_ms(1);
}
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I'm receiving bunch of objects from VCC application.
This is example of one of them:
| Code: |
struct initData {
int idUser;
int counter;
int counter2;
char words[4];
int maxValue;
}
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What I need to do now is collect all this data and update it with the old data on my device ( rewrite it ). As far as the USB example goes, he is sending 2 bytes of data and that's it. How to receive this data from the PC objects ?
Last edited by W_Schauberg on Fri Dec 04, 2009 11:48 am; edited 1 time in total |
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epitalon
Guest
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| Posted: Thu Dec 03, 2009 11:26 am |
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You will have to send any element of your data structure byte per byte.
That is, you have to extract every four bytes of an int, pack them into a buffer of char.
You will have then to send all these chars by packets whose length you choose.
On the PIC, you have to call get_packet() and do the reverse process : that is, gather all bytes in integers.
Alternatively, you could copy all the data structure in a char buffer of sufficient lenth, using memcpy(), and do the reverse on the other side.
But doing this, you are exposed to errors due to different layouts of data structures, and integers (Bigendian, little-endian issue) on both architectures (Intel and Microchip).
Jean-Marie Epitalon |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Thu Dec 03, 2009 1:27 pm |
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In my opinion, copying complete structures rather than invidual bytes would be matter of economic programming. It should be no problem, if the data structures are exactly defined and works with many applications that are communicating through binary protocols.
HID, that has been considered for the project, is working in packets of data ("reports") rather than streams (as e.g. HID does). To allow an easy assignment of data blocks, I would use a type field and a record number in each packet. The type field can be also used to code commands respectively data requests. Every application, that uses HID to transport larger data entities does something similar, e.g. the Microchip HID bootloeader. |
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W_Schauberg
Joined: 17 Sep 2009
Posts: 16
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| Posted: Wed Dec 09, 2009 3:32 pm |
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Hello guys.
Can someone write some example code on this. Just basic stuff, on how to start. ? I look at existing samples but couldn't find anything that could fit to what i need. |
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W_Schauberg
Joined: 17 Sep 2009
Posts: 16
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| Posted: Thu Dec 10, 2009 6:26 am |
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Is this the way to solve the problem....?
| Code: | if (usb_kbhit(1))
{
usb_get_packet(1, datain, 64); //read new packet
switch(cmd)
{
case '1':
adc_value=fread_adc(channel,samples,sample_delay);
adcbyte0=make8(adc_value,0);
adcbyte1=make8(adc_value,1);
usb_put_packet(1, send_buffer, 3, USB_DTS_TOGGLE);
printf("\r\nADC data sent");
cmd=0;
break;
case '2':
usb_put_packet(1,logo,32,USB_DTS_TOGGLE);
printf("\r\n Send !");
break;
}
} |
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