Configuring SL811 to Support a Low-Speed Device Connected to a Full-Speed Hub – KBA91288

Version: **

 

Question: How do you set SL811 to support a low-speed device connected to SL811 via a full-speed hub?

 

Answer:

 

  1.   Set the SL811HS serial interface engine (SIE) to operate at full speed. Bit 5 of register 05h (Control Register 1) = 0.
  2.   Bit 6 of register 0Fh (Control Register 2) = 0 for no change of polarity (full speed) in order to keep the polarity of D+ and D– for full speed.
  3.   Bit 7, Preamble bit of USB-A/USB-B Host Control registers [00h, 08h] = 1 for preamble generation.

For more information on this topic please see Table 11, “Control Register 1 [Address 05h]” in the SL811HS Datasheet.