NuMicro® NUC029LEE/NUC029SEE
32-bit Arm
®
Cortex
®
-M0 Microcontroller
Aug, 2018
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Rev 1.00
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UC029
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Wake Up Enable
System
Power Down
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Y
System
Wake-up
N
Y
Wait 20ms
Wake-up Interrupt
Figure 6.16-2 Wake-up Interrupt Operation Flow
USB interrupt is used to notify users of any USB event on the bus, and user can read EPSTS
(USB_EPSTS[31:8]) and EPEVT7~0 (USB_INTSTS[23:16]) to take necessary responses.
Same as USB interrupt, BUS interrupt notifies users of some bus events, like USB reset,
suspend, time-out, and resume. A user can read USB_ATTR to acknowledge bus events.
6.16.5.6 Power Saving
The USB turns off PHY transceiver automatically to save power while this chip enters Power-
down mode. User can write 0 into USB_ATTR[4] to disable PHY under special circumstances like
suspend to save power.
6.16.5.7 Buffer Control
There is 512 bytes SRAM in the controller and the 8 endpoints share this buffer. User shall
configure ea
ch endpoint’s effective starting address in the buffer segmentation register before the
USB function active. The
“Buffer Control” block is used to control each endpoint’s effective
starting address and its SRAM size is defined in the USB_MXPLDx register.
Figure 6.16-3 depicts the starting address for each endpoint according the content of
USB_BUFSEGx and USB_MXPLDx registers. If the USB_BUFSEG0 is programmed as 0x08h
and USB_MXPLD0 is set as 0x40h, the SRAM size of endpoint 0 is start from 0x108h
and end in 0x148h. (
Note:
The USB SRAM base is 0x100h).