• One of the most over looked circuits  and/or adapters are converters from one medium to another like USB to serial and in this example is USB to TTL.  Hence we have yet another USB to TTL  converter.

   

  Yes there are lots of them out in the market utilizing different chips. What we did with ours was take the CH340 (C or G)  chip added couple of transistors and few passive components and made a dual purpose adapter. First fold is a basic USB to serial TTL converter with all RS232 pins routed to the sides.  Secondly we routed selective Rx/Tx/DTR pins to 6 pin header for standard FTDI pin out used in various programmers.  Thirdly, with couple transistors and resistors we made it auto reset programmer for ESP controllers. This is especially usefull for custom projects using ESP chips where need for part reduction is of concern thus reducing overall cost of the project.
  The auto reset eliminates the need for reset button and forcing GPIO0 to ground in order to put the controller into programming mode
  
  
  
  A 3.3v regulator provides 750mA of current selectable between it and 5.0V to the target board if needed. If jumper is not placed target board will need to be powered by external power source.
  
   

   

   

  
  Features

  o     LCh340c or CH340G controller    
  o     LED indicators
          o Power
          o   Target
  o   Standard 6 pin header for programming    

  o   All RS232 signals from CH340 chip routed to outer headers   

  o   2x3 header for ESP programing with auto reset and programing mode   

  o    mini USB connector

  
    

  
   

  Documents

     Schematic
     Gerber files
     PCB layout files   (easyEDA)
     Bill of Materials