Comments on: Soft Linux kernel hacking for dumping ULPI commands to USB PHY https://billauer.se/blog/2018/09/linux-dump-ulpi-registers/ Anything I found worthy to write down. Thu, 26 Mar 2026 13:15:15 +0000 hourly 1 http://wordpress.org/?v=3.1.2 By: Morgan Monks https://billauer.se/blog/2018/09/linux-dump-ulpi-registers/comment-page-1/#comment-1422 Morgan Monks Tue, 11 Jun 2019 22:15:18 +0000 https://billauer.se/blog/?p=5523#comment-1422 Hi Eli, You got the access to the OTG reg. in the SMSC3320 correct. 0x0A[5] DrvVbus set 1 to enable Vbus 0x0A[6] DrvVbusExternal set to 1 for external vbus (we did not build a charge pump because meeting a realistic Vbus supply current would make the 3320 too big) 0x0A[0] 1 enables the IdPullup and sampling. You can download the ULPI spec for more info. Morgan Monks Hi Eli,

You got the access to the OTG reg. in the SMSC3320 correct.

0x0A[5] DrvVbus set 1 to enable Vbus
0x0A[6] DrvVbusExternal set to 1 for external vbus
(we did not build a charge pump because meeting a realistic Vbus supply current would make the 3320 too big)
0x0A[0] 1 enables the IdPullup and sampling.

You can download the ULPI spec for more info.

Morgan Monks

]]>