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Printer interface to Samsung ARM-7

prasadAradhya prasadAradhya
Note: This was originally posted on 25th June 2009 at http://forums.arm.com

Hi
I am interfacing the Dot matrix printer (EPSON 1000 series)  to an Samsung processor which as ARM - 7 architecture, through Parallel port.
I wanted to print text and graphics. Now i am trying to send text to print and the same i am displaying  on the display. On the display the data sent is displayed correctly,
but on the printer it is displaying 'PPPP' some junck even if i am not sending any data, If i press print button, then it self its printing junck characters.
I am not able to understand why its happening.
I am sending ASCII value of a character  to printer.
I am writing program in Embedded C.
If any one know please help me.
  • Note: This was originally posted on 26th June 2009 at http://forums.arm.com

    Are you using a serial or parallel printer; if it's serial, are you using the correct baud rate, stop-bits etc.?

    s.

    I am using Parallel port. Samsung Processor works with 3.3V so 74HCT245 Ic is used to convert 3.3v to 5V for data pin D0 - D7, and for control pins i have used transistor to provide 5V
  • Note: This was originally posted on 26th June 2009 at http://forums.arm.com

    Sounds like you're driving strobe incorrectly; either too fast, the wrong way around (it is active low), or electrically incorrect (either insufficient voltage, or signal grounds not connected). Note also that the control signals are open collector.

    hth
    s.


    Thank you for your reply SIM,
    Today i checked the strobe pin I am getting 3.3V, Is there will be any problem. I checked in the CRO Strobe pin is going low and high properly. I have given delay by using for loop of count 1000. between strobe low and high. (according to TTL logic 3.3V means High and printer works with TTL logic).
    Since my processor works for 3.3v i have used voltage divider to reduce voltage from 5v to 3.3v for input pins to processor from printer like PE, Busy, Select in. but i am getting only 1.5V instead of 3.3V, due to some load resistance problem. So i am not checking any I/P pins instead i am giving more delay and sending data. But printer is not responding properly, its just printing some junk value.
  • Arm Employee Badge
    Note: This was originally posted on 25th June 2009 at http://forums.arm.com

    Are you using a serial or parallel printer; if it's serial, are you using the correct baud rate, stop-bits etc.?

    s.
  • Arm Employee Badge
    Note: This was originally posted on 26th June 2009 at http://forums.arm.com

    Sounds like you're driving strobe incorrectly; either too fast, the wrong way around (it is active low), or electrically incorrect (either insufficient voltage, or signal grounds not connected). Note also that the control signals are open collector.

    hth
    s.