Otg Core Lpm Configuration Register (Otg_Glpmcfg) - ST STM32L4x6 Reference Manual

USB on-the-go full-speed (OTG_FS)

43.15.14 OTG core LPM configuration register (OTG_GLPMCFG)

Address offset: 0x54
Reset value: 0x0000 0000
31 30 29
Res. Res. Res.
BESL
15 14 13
SLP L1DS
LPMRSP
STS
r r r
Bits 31:29 Reserved, must be kept at reset value.
Bit 28 ENBESL: Enable best effort service latency
Note: Only the updated behavior (described in LPM Errata) is considered in this document
Bits 27:25 LPMRCNTSTS: LPM retry count status
Note: Accessible only in host mode.
Bit 24 SNDLPM: Send LPM transaction
Note: This bit must be set only when the host is connected to a local port.
Note: Accessible only in host mode.
Bits 23:21 LPMRCNT: LPM retry count
Note: Accessible only in host mode.
Bits 20:17 LPMCHIDX: LPM Channel Index
Note: Accessible only in host mode.
1544/1693
28 27 26 25
EN
LPMRCNTSTS
rw r r r
12 11 10 9
BESLTHRS
EN
rw rw rw rw
This bit enables the BESL feature as defined in the LPM errata:
0:The core works as described in the following document:
USB 2.0 Link Power Management Addendum Engineering Change Notice to the USB 2.0
specification, July 16, 2007
1:The core works as described in the LPM Errata:
Errata for USB 2.0 ECN: Link Power Management (LPM) - 7/2007
and so the ENBESL bit should be set to '1' by application SW.
Number of LPM host retries still remaining to be transmitted for the current LPM sequence.
When the application software sets this bit, an LPM transaction containing two tokens, EXT
and LPM is sent. The hardware clears this bit once a valid response (STALL, NYET, or
ACK) is received from the device or the core has finished transmitting the programmed
number of LPM retries.
When the device gives an ERROR response, this is the number of additional LPM retries
that the host performs until a valid device response (STALL, NYET, or ACK) is received.
The channel number on which the LPM transaction has to be applied while sending an LPM
transaction to the local device. Based on the LPM channel index, the core automatically
inserts the device address and endpoint number programmed in the corresponding channel
into the LPM transaction.
DocID024597 Rev 3
24 23 22 21
SND
LPMRCNT
LPM
rs rw rw rw
8 7 6 5
L1SS REM
EN WAKE
rw rw rw/r rw/r
20 19 18 17
LPMCHIDX
rw rw rw rw
4 3 2 1
LPM
BESL
ACK
rw/r rw/r rw/r rw
RM0351
16
L1RSM
OK
r
0
LPM
EN
rw