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X-communication between a website and a propeller C3 — Parallax Forums

X-communication between a website and a propeller C3

JChrisJChris Posts: 58
edited 2014-07-20 06:52 in General Discussion
Hello,
I am trying to achieve some form of data exchange between a website, that I developed in PHP, and a C3 development board.
However, I am experiencing some difficulties in receiving the data, on the propeller side, and I wonder whether somebody faced the same issue and managed to solve it.

Practically speaking I am sending the data onto a serial port of the PC. The propeller is plugged on this same port through a USB serial adapter. In this case, port 17, with 8N1 communication parameters (see below).
The baud rate has been set at 38400 on both sides (PC and propeller) and I tried different values (ranging from 9600 to 115200) without seeing any difference.
Checking with the ProScope data logic analyzer I was able to validate that the 8 bytes I was sending were actually well received on Pin 31 of the propeller.

The thing is: I cannot get this data read by the propeller from the input buffer.

To avoid possible conflicts on pin 30 and 31, I am using a LCD connected to pin 1 to display the result, i.e. the bytes I am trying to fetch from the buffer.
The RX method (in the FullduplexSerial library) is used to fetch the data but it gets stuck and I am not able to retrieve anything from the input buffer. It seems that RX waits forever for a character to come.

Any thoughts on what could be wrong? Any help would be appreciated.

Extract from the PHP sender
send on port php.png

Spin receiver program
code propeller.png
send on port php.png
383 x 146 - 23K
code propeller.png
342 x 401 - 56K

Comments

  • SRLMSRLM Posts: 5,045
    edited 2014-07-16 10:29
    It looks like you're mixing a byte method (PC.Rx) with a string method (LCD.Str).
  • JChrisJChris Posts: 58
    edited 2014-07-16 15:15
    I tried to use LCD.Hex. I also tested another library "Serial_Lcd", using the "putc" function but to no avail.
    Any other suggestion?
  • SRLMSRLM Posts: 5,045
    edited 2014-07-16 15:30
    You're still mixing up the functions. Using vanilla FDS, you can just do this:
    repeat
    LCD.tx(PC.rx)

    That reads a single byte from the PC FDS variable, and outputs that single byte to the LCD FDS variable.
  • JChrisJChris Posts: 58
    edited 2014-07-17 13:10
    Thank you for your answer, It's working now but the problem was not in the code... My propeller board was plugged on a 4-port USB hub and this was the root cause of the problem. I plugged it directly on the PC USB port and it's now working fine.
    LESSON learned: never plug the propeller on a USB Hub when transferring data between a PC and a propeller board.
    Thanks for your help
  • RS_JimRS_Jim Posts: 1,766
    edited 2014-07-20 06:52
    LESSON learned: never plug the propeller on a USB Hub when transferring data between a PC and a propeller board.
    Thanks for your help

    My propeller is always connected to my PC via a powered hub!
    Jim
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