mc9s08jm16 Freescale Semiconductor, Inc, mc9s08jm16 Datasheet - Page 317

• Manufacturer Part Number: mc9s08jm16
• Description: S08jm 8-bit Usb Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

When the USB module receives a USB token on an enabled endpoint, it interrogates the BDT. The USB
module reads the corresponding endpoint BD entry and determines if it owns the BD and corresponding
data buffer.
17.4.2.3
The buffer descriptors (BDs) are groups of registers that provide endpoint buffer control information for
the USB module and the MCU. The BDs have different meanings based on who is reading the BD in
memory.
The USB module uses the data stored in the BDs to determine:
The microcontroller uses the data stored in the BDs to determine:
Freescale Semiconductor
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Who owns the buffer in system memory
Data0 or Data1 PID
Release Own upon packet completion
Data toggle synchronization enable
How much data to be transmitted or received
Where the buffer resides in the buffer RAM.
Who owns the buffer in system memory
Data0 or Data1 PID
The received TOKEN PID
Buffer Descriptor Formats
USB RAM
Offset
0x1D
0x00
0x1E
0x1F
0x20
0xFF
Table 17-21. USB RAM Organization
MC9S08JM16 Series Data Sheet, Rev. 2
BDT
USB RAM available for endpoint buffers
USB RAM Description of Contents
RESERVED
RESERVED
Endpoint 0 IN
Endpoint 0, OUT
Endpoint 1
Endpoint 2
Endpoint 3
Endpoint 4
Endpoint 5, Buffer EVEN
Endpoint 5, Buffer ODD
Endpoint 6, Buffer EVEN
Endpoint 6, Buffer ODD
Universal Serial Bus Device Controller (S08USBV1)
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