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Need schematic for Parallax USB2SER-inverter for BS2 — Parallax Forums

Need schematic for Parallax USB2SER-inverter for BS2

gregoriovaldiviagregoriovaldivia Posts: 5
edited 2011-10-13 12:17 in General Discussion
Dave Andreae replied "Yes, the USB2SER will require an inverter." on Thursday, September 22, 2011 8:21 AM [SUPPORT #MNX-474-48025]: Parallax USB2SER Development Tool.

What is the schematic needed for this application? The Product Data for USB2SER RevD is missing on the Parallax webpage. Grgr

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-09-25 07:43
    Use the schematic for the RevC product. Parallax will often make small changes to a product to improve manufacturability without any functional changes and that can result in a change to the product revision letter.
  • gregoriovaldiviagregoriovaldivia Posts: 5
    edited 2011-10-13 08:50
    The schematic indicates that BS2 requires an inverted signal but does not indicate what pin needs to be inverted. Where would I insert a NOT gate? Or possibly, is there a suggestion where in Parallax literature there is detailed requirements for the signal? Pls advise.
  • Mike GreenMike Green Posts: 23,101
    edited 2011-10-13 12:17
    Here are links to the schematics for the serial Board of Education and the USB Board of Education, both from the corresponding Parallax webstore pages for the products. Notice the inverters on the TX and RX signals from the FTDI USB to Serial chip. The 150 Ohm resistors on the USB2SER signals shouldn't make a significant difference. You'll need some kind of pullup resistor between the RST line and +5V. A 2.2K or 4.7K resistor should work.

    General advice: Adapt something that already works in other similar circumstances, but make sure to understand the similarities and differences between the situations.
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