519
/
838
Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
19.5.5
USB frame number register (USB_FN)
Address offset: 0x48
Reset value: 0x0000 0XXX, X stands for undefined value
Bit Field
Name
Description
31:16
Reserved
Reserved, the reset value must be maintained.
15
RXDP_STS
D+ status
Represents the state of the USB D+ line, and can detect the occurrence of a resume
condition in the suspend state.
14
RXDM_STS
D- status
Represents the state of the USB D- line, and can detect the occurrence of a resume
condition in the suspend state.
13
LOCK
Lock USB
This bit is set by hardware if at least 2 PID SOF token packets are detected
continuously after the end of an USB reset condition or after the end of an USB
resume sequence.
Note:
1
、
When USB_FN.LOCK = 1, the frame counter will stop counting before the USB
module is reset or the USB bus is suspended.
12:11
LSTSOF[1:0]
Lost SOF flag
The hardware increments this bit every time the USB_STS.ESOF event occurs, and
once the PID SOF token packet is received, the hardware clears this bit.
10:0
FNUM[10:0]
Number of frames
Hardware increments this bit every time the USB module receives a PID SOF token
packet.
19.5.6
USB device address register (USB_ADDR)
Address offset: 0x4C
Reset value: 0x0000 0000