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The problem of LaunchPAD(G2553) direct connect to pc comport

kejian lin
Intellectual 675 points
Other Parts Discussed in Thread: MAX3232

HI

     I have a lauchPAD V1.5 with 32678 crystal installed , if I use USB connnect pad , the function of uart communication is OK, but if I connect P1.1 / P1.2 / GND  to the PC's comport ,  communication not stable , PC can receive data, but the data is not correct.

     How to solve this program

Lin Kejian

  • 0
    Guru 34453 points

    kejian lin said:

         I have a lauchPAD V1.5 with 32678 crystal installed , if I use USB connnect pad , the function of uart communication is OK, but if I connect P1.1 / P1.2 / GND  to the PC's comport ,  communication not stable , PC can receive data, but the data is not correct.

    I hope that you are not using direct wire connection between MSP430 UART (0V .. 3.3V) and PC UART (-12V .. +12V). There must be some RS232/TTL3V converter between... http://www.futurlec.com/Mini_RS232_TTL_3V.shtml

  • 0 in reply to zrno soli
    Guru 227245 points

    zrno soli said:
    PC UART (-12V .. +12V)

    Actually +12V..-12V, as +12V stands for low and -12V for high. And, more precisely, it is 3..12V. Many PC COM ports only have 5V level output while accepting from 3 to 12V.

    However, without a level shifter like the MAX3232, a direct connection will likely damage the MSP port pin. And even if not, the MSPs '1' output will be interpreted as '0' and the MSPs '0' output is an illegal signal level to the COM port.

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