MCF5253VM140J Freescale Semiconductor, MCF5253VM140J Datasheet - Page 565

• Manufacturer Part Number: MCF5253VM140J
• Description: IC MCU 2.1MIPS 140MHZ 225MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: MCF525xr

Specifications of MCF5253VM140J

• Core Processor: Coldfire V2
• Core Size: 32-Bit
• Speed: 140MHz
• Connectivity: CAN, EBI/EMI, I²C, QSPI, UART/USART, USB OTG
• Peripherals: DMA, WDT
• Program Memory Type: ROMless
• Ram Size: 128K x 8
• Voltage - Supply (vcc/vdd): 1.08 V ~ 1.32 V
• Data Converters: A/D 6x12b
• Oscillator Type: External
• Operating Temperature: -20°C ~ 70°C
• Package / Case: 225-MAPBGA
• Processor Series: MCF525x
• Core: ColdFire V2
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Program Memory Size: -
• Lead Free Status / Rohs Status: Details

24.9.12.2.9 Rebalancing the Periodic Schedule
The system software must occasionally adjust a periodic queue head's S-mask and C-mask fields during
operation. This need occurs when adjustments to the periodic schedule create a new bandwidth budget and
one or more queue head's are assigned new execution footprints (that is, new S-mask and C-mask values).
It is imperative that the system software must not update these masks to new values in the midst of a split
transaction. In order to avoid any race conditions with the update, the host controller provides a simple
assist to the system software. The system software sets the Inactivate-on-next-Transaction (I) bit to signal
the host controller that it intends to update the S-mask and C-mask on this queue head. The system
software then waits for the host controller to observe the I-bit is set and transitions the Active bit to a zero.
The rules for how and when the host controller clears the Active bit are:
The system software must save transfer state before setting the I-bit. This is required so that it can correctly
determine what transfer progress (if any) occurred after the I-bit was set and the host controller executed
it's final bus-transaction and cleared the Active bit.
After the system software has updated the S-mask and C-mask, it must then reactivate the queue head.
Since the Active bit and the I-bit cannot be updated with the same write, the system software needs to use
the following algorithm to coherently re-activate a queue head that has been stopped using the I-bit.
Setting the Halted bit inhibits the host controller from attempting to advance the queue between the time
the I-bit is cleared and the Active bit is set.
24.9.12.3 Split Transaction Isochronous
Full-speed isochronous transfers are managed using the split-transaction protocol through a USB 2.0
transaction translator in a USB 2.0 hub. The host controller utilizes siTD data structure to support the
special requirements of isochronous split-transactions. This data structure uses the scheduling model of
isochronous TDs (see
model of iTDs) with the contiguous data feature provided by queue heads. This simple arrangement allows
a single isochronous scheduling model and adds the additional feature that all data received from the
endpoint (per split transaction) must land into a contiguous buffer.
Freescale Semiconductor
•
•
1. Set the Halted bit, then
2. Clear the I-bit, then
3. Set the Active bit and clear the Halted bit in the same write.
If the Active bit is cleared, no action is taken. The host controller does not attempt to advance the
queue when the I-bit is set.
If the Active bit is set and the SplitXState is DoStart (regardless of the value of S-mask), the host
controller simply clears the Active bit. The host controller is not required to write the transfer state
back to the current qTD. Note that if the S-mask indicates that a start-split is scheduled for the
current micro-frame, the host controller must not issue the start-split bus transaction; it must clear
the Active bit.
Section 24.9.8, “Managing Isochronous Transfers Using iTDs,”
MCF5253 Reference Manual, Rev. 1
Universal Serial Bus Interface
for the operational
24-103