Table 17-2. USB Memory Access From CCS
CCS 8 Bit
CCS 16 Bit
CCS 32 Bit
Address
Displayed Data
Address
Displayed Data
Address
Displayed Data
0x00
0x00
0x00
0x1100
0x00
0x11001100
0x01
0x00
0x01
0x1100
0x02
0x33223322
0x02
0x22
0x02
0x3322
0x04
0x55445544
0x03
0x22
0x03
0x3322
0x06
0x77667766
0x04
0x44
0x04
0x5544
0x08
0x99889988
0x05
0x44
0x05
0x5544
0x0A
0xBBAABBAA
0x06
0x66
0x06
0x7766
0x0C
0xDDCCDDCC
0x07
0x66
0x07
0x7766
0x0E
0xFFEEFFEE
0x08
0x88
0x08
0x9988
0x09
0x88
0x09
0x9988
0x0A
0xAA
0x0A
0xBBAA
0x0B
0xAA
0x0B
0xBBAA
0x0C
0xCC
0x0C
0xDDCC
0x0D
0xCC
0x0D
0xDDCC
0x0E
0xEE
0x0E
0xFFEE
0x0F
0xEE
0x0F
0xFFEE
17.3 Initialization and Configuration
To use the USB Controller, the clock for the USB controller must first be configured. USBCLK is driven via the
second PLL within the chip. The PLL should be configured to operate at 60MHz via the PLL2CTL, PLL2MULT,
PLL2STS registers. After the PLL is enabled and locked,the controller can be clocked by enabling the peripheral
in the PCLKCR3 register. In addition to the clock,the USB PHY must be enabled. Configure the USBIOEN field
in the GPACTRL2 register to enable USB functionality on the designated pins. After the clock has been enabled
and the USB PHY turned on the USB peripheral is ready for operation and the associated software initialization
routines may be called.
17.3.1 Pin Configuration
In order to give the user more flexibiliity, the signals External Power Enable (EPEN) and Power Fault (PFLT)
were not implemented in hardware. Instead, it is left up to the user to implement these signals in software.
Examples of how to implement these signals in software can be found in the F2806x USB Software Guide.
When using the device controller portion of the USB controller in a system that also provides host functionality,
the power to V
BUS
must be disabled to allow the external host controller to supply power. Usually, the EPEN
signal is used to control the external regulator and should be negated to avoid having two devices driving the
V
BUS
power pin on the USB connector.
When the USB controller is acting as a host, it is in control of two signals that are attached to an external voltage
supply that provides power to V
BUS
. The Host controller uses the EPEN signal to enable or disable power to
the V
BUS
pin on the USB connector. An input pin, PFLT, provides feedback when there has been a power fault
on V
BUS
. The PFLT signal can be configured to either automatically negate the EPEN signal to disable power,
and/or it can generate an interrupt to the interrupt controller to allow software to handle the power fault condition.
The polarity and actions related to both EPEN and PFLT are fully configurable in the USB controller. The
controller also provides interrupts on device insertion and removal to allow the Host controller code to respond to
these external events.
Universal Serial Bus (USB) Controller
1068
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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