What's the difference between Prop Plug and USB2Ser Dev. Tool?

Comments

• Duane C. Johnson Posts: 955

  2011-03-30 04:15 edited 2011-03-30 04:15

  There is only a slight difference in the schematic between the Prop Plug and USB2Ser Dev. Tool.
  This difference is in the 5V / 3.3V connections to the FTDI chip.
  However, this looks to be insignificant to its operation.
  The important part is the 4 pin connector making connection to your board is the same.
  I would say you should be good to go.
  
  Duane
• Paul Sr. Posts: 435

  2011-03-30 08:01 edited 2011-03-30 08:01

  BE CAREFUL - the 4 Pin connectors are NOT the same configuration!
  
  Prop Plug: VSS RES TX RX
  
  USB2SER: RST TX RX VSS
• Duane C. Johnson Posts: 955

  2011-03-30 08:19 edited 2011-03-30 08:19

  That's the difference. I hadn't noticed that.
  The USB2Ser Dev. Tool is like many of the other "non parallax" adapters.
  If my first adapter was the USB2Ser Dev. Tool I wouldn't have had to make
  all these gender changers.
  
  See another post regarding the RST pin:
  http://forums.parallax.com/showthread.php?130412-SPIN-Problems-Using-Non-Parallax-USB-to-TTL-RS-232-Adapter.&p=986154#post986154
  
  Duane
• MagIO2 Posts: 2,243

  2011-03-31 04:47 edited 2011-03-31 04:47

  You can make it a prop-plug )
  http://forums.parallax.com/showthread.php?129076-PropPlug-does-not-work-parallax-have-mercy
• Beau Schwabe Posts: 6,572

  2011-04-01 23:51 edited 2011-04-01 23:51

  For the record, you don't need to make any modifications between the PropPlug and the USB2SER other than how you orient the plug into the socket. See attached images.
  
  The difference is that the USB2SER is really designed for 5V applications, but should be ok "in a pinch" for the Propeller, since there are 1K current limiting resistors on the RX and TX lines.
  
  
  

  PropPlug: (looking at the front side)
  
   VSS RES TX RX
       
  USB2SER: (looking at the back side)
      
       RES TX RX VSS
  

  
  ...By shifting the Plug over by one, the RES,TX, and RX align. The only signal you need to carry is VSS. A simple jumper wire will do the job.

  

  

  PROP_PLUG.jpg

  1024 x 768 - 91K

  

  

  USB2SER.jpg

  1024 x 768 - 89K

  

  

  schematic.JPG

  520 x 248 - 19K

  PROP_PLUG.jpg 91.5K

  USB2SER.jpg 88.6K

  schematic.JPG 19.1K
• MagIO2 Posts: 2,243

  2011-04-02 11:47 edited 2011-04-02 11:47

  Hi Beau,
  
  nice tip. BUT ... the 1k resistors have been replaced by 150Ohm resistors with REV B and C. That's why I choosed to add 680Ohm.
  
  Additionally I don't need it as a Basic Stamp programmer, thus I made it a full Prop-Plug ;o)
• Beau Schwabe Posts: 6,572

  2011-04-02 17:35 edited 2011-04-02 17:35

  MagIO2,
  
  "the 1k resistors have been replaced by 150Ohm resistors with REV B and C" - I see that... I looked at the revA datasheet.
  
  Still "in a pinch" it should be ok, but I wouldn't recommend it for a permanent setup. The FT232RQ datasheet indicates a maximum OUTPUT voltage from the datasheet (page 16 table #7) when VCCIO is powered from a 5V supply is at 4.9V(Max) ; 4.1V(Typical) ... The Diode drop of the Propeller (0.4V) and the difference of 3.3V amounts to 1.2V across the 150 Ohm resistor... or 8mA(Max) ;2.7mA(Typical) . The addition of a 680 Ohm resistor lessens the current to 1.4mA(Max) ;482uA(Typical).
  
  
  Datasheet reference:
  http://datasheet.octopart.com/FT232RQ-FTDI-datasheet-120501.pdf
• davidsaunders Posts: 1,559

  2011-05-02 19:48 edited 2011-05-02 19:48

  Because of the issues with the FTDI chips in some cases (certain kernels do not have a driver etc.), I would like to point out that there is an open source library that can be statically linked to provide the driver functionality with out a kernel linked driver (you just have to have working USB). for more see:
  http://www.intra2net.com/en/developer/libftdi/
  
  After searching the forums, this seems the best place for this (short of starting a thread).