
Universal Serial Bus Interface – On-The-Go Module
21-6
Freescale Semiconductor
21.2.1
USB OTG Control and Status Signals
The USB OTG module uses a number of control and status signals to implement the OTG protocols. The
USB OTG module must be able to individually enable and disable the pull-up and pull-down resistors on
DP and DM, and it must be able to control and sense the levels on the USB VBUS line.
These control and status signals are implemented on chip as registers within the chip-configuration module
(CCM) to minimize the pin-count on the device. With firmware, the system designer uses an external
device to manage the OTG functions to implement communications across the I
2
C bus or GPIO pins.
The OTG controller status register (UOCSR) implements as follows:
•
Writes to the UOCSR register from the firmware set the corresponding bits on the USB interface.
•
When the USB OTG module outputs change, the corresponding bits on the UOCSR register are
updated, and a maskable interrupt is generated.
ULPI_DIR
I
Direction. ULPI_DIR controls data bus direction. When PHY has data to transfer to USB port,
it drives ULPI_DIR high to take ownership of the bus. When the PHY has no data to transfer,
it drives ULPI_DIR low and monitors the bus for link activity. The PHY pulls ULPI_DIR high
when the interface cannot accept data from the link. For example, when PHY’s PLL is not
stable.
State
Meaning
Asserted—PHY has data to transfer to the link.
Negated—PHY has no data to transfer.
Timing Synchronous to USB_CLKIN or ULPI_CLK.
ULPI_NXT
I
Next data. PHY asserts ULPI_NXT to throttle data. When USB port sends data to the PHY,
ULPI_NXT indicates when PHY accepts the current byte. The USB port places the next byte
on the data bus in the following clock cycle. When the PHY sends data to USB port, ULPI_NXT
indicates when a new byte is available for USB port to consume.
State
Meaning
Asserted—PHY is ready to transfer byte.
Negated—PHY is not ready.
Timing Synchronous to ULPI_CLK.
ULPI_STP
O
Stop. ULPI_STP indicates the end of a transfer on the bus.
State
Meaning
Asserted—USB asserts this signal for one clock cycle to stop the data stream
currently on the bus. If the USB port sends data to the PHY, ULPI_STP
indicates the last data byte was previously on the bus. If the PHY is sending
data to the USB port, ULPI_STP forces the PHY to end its transfer, deassert
ULPI_DIR, and relinquish control of the data bus to the USB port.
Negated—Indicates normal operation.
Timing Synchronous to USB_CLK or ULPI_CLK
ULPI_DATA[7:0]
I/O Data bit n. ULPI_DATATn is bit n of the 8-bit, bi-directional data bus used to carry USB, register,
and interrupt data between the USB port controller and the PHY.
State
Meaning
Asserted—Data bit n is 1
.
Negated—Data bit n is 0.
Timing Synchronous to USB_CLK or ULPI_CLK
Table 21-2. USB OTG Signal Descriptions (continued)
Signal
I/O
Description
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...