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ALFAT Manual 2.10 problems


#1
  1. Page 14: pins 35. 36 “NC if PHY is used. Add 22ohm resistor in series
    if used”. So NC or 22ohms? Can’t have both…

  2. Page 60: “ALFAT generates a 19.2 MHz clock at pin 21” — isn’t it pin 41 (PA8?)


#2

@ Simon from Vilnius -

  1. So NC or 22ohms? => depends on you!

    • if HS PHY is used, then not connect.
    • if you are going to use FS on this port, 22 ohm resistors are needed.
    • If HS PHY is used and 22 ohm resistors are also used, we found few USB thumbs drive are not happy, but not all.
    • Pin 41 is for input clock to feed/select mode of PHY chip
    • Pin 21 is ULPI interface clock.
      So you are right, document will be updated for this.

:slight_smile:


#3

Ok that’s some convoluted way to say things. Consider correcting manual to something clearler…

Page 15 says 19.2MHz clock is generated on pin 41. Page 60 says it’s pin 21. Which one is correct?


#4

@ Simon from Vilnius -

“Page 15 says 19.2MHz clock is generated on pin 41.” is correct one


#5

Just for more clear, “we found few USB thumbs drive are not happy if initialize in FS mode”, but HS should work fine. It also means once HS PHY is implemented, we recommend should use HS mode, it does not matter if 22ohm are connected or not in HS mode.