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nando88
Joined: 25 Aug 2013
Posts: 28
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| Read a byte[] sent through usb to dev board |
 Posted: Wed Sep 03, 2014 1:06 pm |
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I have a pic18f4550 dev board, and have successfully connected it to my laptop. I'm sending a byte[], through usb to this dev board, using c#, but nothing happens. I think the problem is in the code that I'm using for the dev board:
| Code: |
#include <ex_usb_common.h>
#include <usb_desc_cdc.h>
#include <usb_cdc.h>
static void my_cdc_demo(void)
{
int8 received_char;
if(!usb_cdc_kbhit())
return;
received_char = usb_cdc_getc();
if(received_char == '1')
{
output_high(PIN_B6); // 1 = Turn on LED
}
if(received_char == '0') // 0 = Turn off LED
{
output_low(PIN_B6);
}
// All characters other than '0' or '1' are ignored.
}
//===========================
void main(void)
{
output_low(PIN_B0);
usb_init_cs();
while(TRUE)
{
usb_task();
if(usb_enumerated())
{
my_cdc_demo();
delay_ms(1);
}
}
}
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I think the problem is in this line:
| Code: |
int8 received_char;
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this is because I'm sending a byte[], and in the dev board, I'm expecting an int8.
This is the code I'm using to send the byte[] in c#:
| Code: |
int sd = 0;
int to = 1;
byte[] sd2 = BitConverter.GetBytes(sd);
byte[] to2 = BitConverter.GetBytes(to);
ComPort.Write(sd2,0,4);
//and
ComPort.Write(to2,0,4);
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Can someone please tell me how to fix this? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Sep 03, 2014 1:17 pm |
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I think you still don't know the difference between an integer 1 and
and an ASCII 1. The integer's value is 0x01. The ASCII value is 0x31.
Look it up. They are not the same.
Also, you need to know how the C language represents an integer 1
and an ASCII 1. An integer can be represented as 1, 0x01, etc.
An ASCII 1 is put in single quotes '1', if you are using it as an individual
byte. This is all critical, elementary, basic, essential C knowledge.
The byte values are 0x01 for the integer value and 0x31 for the ASCII.
If you compare them, they will not be equal.
If you send an integer 1 by USB, then test for integer 1 in your PIC code.
Or, if you send an ASCII 1 by USB, then test for an ASCII 1 in your PIC.
The same thing is true for an integer 0 and an ASCII 0. |
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nando88
Joined: 25 Aug 2013
Posts: 28
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| Posted: Wed Sep 03, 2014 7:06 pm |
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I changed my code in the desktop application, to:
| Code: |
ComPort.Write(BitConverter.GetBytes('0'),0,4);
ComPort.Write(BitConverter.GetBytes('1'),0,4);
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This is because I need to send an ascii character inside a byte.
But I still can't turn on the led with my pic dev board.
Can someone please help me? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 04, 2014 12:58 am |
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I have no idea about C#. I searched with Google and quickly found a
sample application for C++:
http://www.orgler.it/visualc01.htm
I compiled it with MSVC++ vs. 6.0, and it worked for its default setting
of Com1 as the comport. So I know that code sample app works.
I then loaded my 18F4550 test board with the USB software that I posted
in your previous thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=52722&start=8
I ran that program and went to Windows Device Manager and looked
in the Com ports section and found that USB 18F4550 board was assigned
to Com5.
I then used "Find in Files" in MSVC++ to search the sample C++ program
for COM1. I found that line, and edited it to use COM5 instead.
I compiled the app in Release mode and made the RS232.exe file
and I ran it.
I then typed '1' in the text box and clicked the "Send text to RS232" button
and the LED on the 18F4550 board turned on. I then typed '0' and sent
it, and the LED turned off. It's working.
-----------------
This is not a C# or C++ forum. I did all this stuff above just to show you
how easy it is to do it. You need use Google, find a C# or C++ forum
and do it. Or use the source code from the website link above and learn
how to do it. |
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