1. Enable Host Mode (CTL[HOST_MODE_EN]=1). The pull-down resistors are
enabled, and pull-up disabled. Start of Frame (SOF) generation begins. SOF counter
loaded with 12,000. Disable SOF packet generation to eliminate noise on the USB by
writing the USB enable bit to 0 (CTL[USB_EN]=0).
2. Enable the ATTACH interrupt (INTEN[ATTACHEN]=1).
3. Wait for ATTACH interrupt (ISTAT[ATTACH]). Signaled by USB peripheral
device pull-up resistor changing the state of DPLUS or DMINUS from 0 to 1 (SE0 to
J or K state).
4. Check the state of the JSTATE and SE0 bits in the control register. If the connecting
device is low speed (JSTATE bit is 0), set the low-speed bit in the address registers
(ADDR[LS_EN]=1) and the Host Without Hub bit in endpoint 0 register control
(ENDPT0[HOSTWOHUB]=1).
5. Enable RESET (CTL[RESET]=1) for 10 ms.
6. Enable SOF packet to keep the connected device from going to suspend
(CTL[USB_EN=1]).
7. Enumerate the attached device by sending the appropriate commands to the default
control pipe of the connected device.
To complete a control transaction to a connected device:
1. Complete all the steps to discover a connected device
2. Set up the endpoint control register for bidirectional control transfers ENDPT0[4:0]
= 0x0d.
3. Place a copy of the device framework setup command in a memory buffer.
4. Initialize current even or odd TX EP0 BDT to transfer the 8 bytes of command data
for a device framework command (for example, a GET DEVICE DESCRIPTOR).
• Set the BDT command word to 0x00080080 –Byte count to 8, OWN bit to 1.
• Set the BDT buffer address field to the start address of the 8 byte command
buffer.
5. Set the USB device address of the peripheral device in the address register
(ADDR[6:0]). After the USB bus reset, the device USB address is zero. It is set to
some other value usually 1 by the Set Address device framework command.
Chapter 43 Universal Serial Bus Full Speed OTG Controller (USBFSOTG)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 1111
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