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2016-04-28 - Giant Gecko Family - d0053_Rev1.20
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Bit
Name
Reset
Access
Description
Interrupt ensures the core is not reading from the FIFO. USB_GRSTCTL.AHBIDLE ensures the core is not writing anything to the
FIFO. Flushing is normally recommended when FIFOs are reconfigured. FIFO flushing is also recommended during device endpoint
disable. The application must wait until the core clears this bit before performing any operations. This bit takes eight clocks to clear.
4
RXFFLSH
0
RW1H
RxFIFO Flush host and device
The application can flush the entire RxFIFO using this bit, but must first ensure that the core is not in the middle of a transaction. The
application must only write to this bit after checking that the core is neither reading from the RxFIFO nor writing to the RxFIFO. The
application must wait until the bit is cleared before performing any other operations. This bit requires 8 clocks to clear.
3
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
2
FRMCNTRRST
0
RW1H
Host Frame Counter Reset host only
The application writes this bit to reset the frame number counter inside the core. When the frame counter is reset, the subsequent
SOF sent out by the core has a frame number of 0. When application writes 1 to the bit, it might not be able to read back the value
as it will get cleared by the core in a few clock cycles.
1
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
0
CSFTRST
0
RW1H
Core Soft Reset host and device
Resets the core by clearing the interrupts and all the CSR registers except the following register bits:
USB_PCGCCTL.RSTPDWNMODULE, USB_PCGCCTL.GATEHCLK, USB_PCGCCTL.PWRCLMP, USB_GUSBCFG.FSINTF,
USB_HCFG.FSLSPCLKSEL, USB_DCFG.DEVSPD.
All module state machines (except the AHB Slave Unit) are reset to the IDLE state, and all the transmit FIFOs and the receive FIFO
are flushed. Any transactions on the AHB Master are terminated as soon as possible, after gracefully completing the last data phase
of an AHB transfer. Any transactions on the USB are terminated immediately. The application can write to this bit any time it wants
to reset the core. This is a self-clearing bit and the core clears this bit after all the necessary logic is reset in the core, which can
take several clocks, depending on the current state of the core. Once this bit is cleared software must wait at least 3 clock cycles
before doing any access to the core. Software must also must check that bit 31 of this register is 1 (AHB Master is IDLE) before
starting any operation.
15.6.13 USB_GINTSTS - Interrupt Register
This register interrupts the application for system-level events in the current mode (Device mode or Host
mode). Some of the bits in this register are valid only in Host mode, while others are valid in Device
mode only. This register also indicates the current mode. To clear the interrupt status bits of type RW1H,
the application must write 1 into the bit.
The FIFO status interrupts are read only; once software reads from or writes to the FIFO while servicing
these interrupts, FIFO interrupt conditions are cleared automatically.
The application must clear the USB_GINTSTS register at initialization before unmasking the interrupt
bit to avoid any interrupts generated prior to initialization.
Offset
Bit Position
0x3C014
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reset
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
Access
RW1H
RW1H
RW1H
RW1H
R
R
R
RW1H
RW1H
RW1H
RW1H
R
R
RW
RW1H
RW1H
RW1H
RW1H
RW1H
R
R
R
R
RW1H
R
RW1H
R
Name
WKUPINT
SESSREQINT
DISCONNINT
CONIDSTSCHNG
PTXFEMP
HCHINT
PRTINT
RESETDET
FETSUSP
INCOMPLP
INCOMPISOIN
OEPINT
IEPINT
EOPF
ISOOUTDROP
ENUMDONE
USBRST
USBSUSP
ERLYSUSP
GOUTNAKEFF
GINNAKEFF
NPTXFEMP
RXFLVL
SOF
OTGINT
MODEMIS
CURMOD
Bit
Name
Reset
Access
Description
31
WKUPINT
0
RW1H
Resume/Remote Wakeup Detected Interrupt host and device
Wakeup Interrupt during Suspend state. In Device mode this interrupt is asserted only when Host Initiated Resume is detected on
USB. In Host mode this interrupt is asserted only when Device Initiated Remote Wakeup is detected on USB. This bit can be set
only by the core and the application should write 1 to clear.
30
SESSREQINT
0
RW1H
Session Request/New Session Detected Interrupt host and
device
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