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WiFi to serial TTL project

Discussion in 'Radio and Wireless' started by t50ufo, Feb 15, 2017.

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  1. t50ufo


    Jan 19, 2013
    Currently attempting to make a WiFi to serial device that will control the mount on my computerised telescope. I have got myself an HLK-RM04 module readily available online. I am not really into the fine art of electronics but know my resistors from my capacitors.

    I have successfully hooked up a bluetooth to serial module to control my mount using an HC-06 slave module which outputs to serial TTL by default I believe and works fine.

    The HLK-RM04 is the development board version. What I need is some help with the serial/TTL output from the module.

    In the circuit diagram the serial out TX /RX are listed as pins 20 RX and 21 TX these are accessed on the circuit board as 2 solder hole connections marked TX-3.3VTTL and RX-3.3VTTL but there is also the female serial socket on the board showing as pins 323RX and 232TX on the underside of the board. I can get the wireless connection from the module ok from iPad and PC laptop but can not make the connection to the mount (serial device).

    Can anyone shed any light on which are the correct TX/RX output pins using TTL or do I need a 323 to TTL converter like a sparkfun MAX3232 (which I also have). Any help would be much appreciated.
  2. BobK


    Jan 5, 2010
    I expect both are active, one being TTL levels, the other being RS-232 levels.

    A link to a datasheet would help us confirm that.

  3. t50ufo


    Jan 19, 2013
    Link to data sheets etc. The HC-06 Bluetooth module is sending the correct signal. The HLK-RM04 is not. I am trying to find out how to output the same signal from the HLK-RM04. This module is working on a youtube example but the HLK module is interfacing to the mount via a handset so it must be converting the signal correctly. Any help much appreciated.

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