MC68MH360EM25L Freescale Semiconductor, MC68MH360EM25L Datasheet - Page 598

• Manufacturer Part Number: MC68MH360EM25L
• Description: IC MPU QUICC ETHER 25MHZ 240FQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68MH360EM25L

• Processor Type: M683xx 32-Bit
• Speed: 25MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 240-FQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

Serial Management Controllers (SMCs)
Although RBPTR need never be written by the user in most applications, it may be modified
by the user when the receiver is disabled or when the user is sure that no receive buffer is
currently in use.
7.11.4.5 TRANSMITTER BUFFER DESCRIPTOR POINTER (TBPTR). The TBPTR for
each SMC channel points to the next BD that the transmitter will transfer data from when it
is in idle state or to the current BD during frame transmission. After a reset or when the end
of the BD table is reached, the CP initializes this pointer to the value programmed in the
TBASE entry. Although TBPTR need never be written by the user in most applications, it
may be modified by the user when the transmitter is disabled or when the user is sure that
no transmit buffer is currently in use (e.g., after a STOP TRANSMIT command is issued, or
after a GRACEFUL STOP TRANSMIT command is issued, and the frame completes its
transmission.)
7.11.4.6 OTHER GENERAL PARAMETERS. Additional parameters are listed in Table 7-
12. These parameters do not need to be accessed by the user in normal operation, and are
listed only because they may provide helpful information for experienced users and for
debugging.
The Rx and Tx internal data pointers are updated by the SDMA channels to show the next
address in the buffer to be accessed.
The Tx internal byte count is a down-count value that is initialized with the Tx BD data length
and decremented with every byte read by the SDMA channels. The Rx internal byte count
is a down-count value that is initialized with the MRBLR value and decremented with every
byte written by the SDMA channels.
The Rx internal state, Tx internal state, Rx temp, Tx temp, and reserved areas are for RISC
use only.
7.11.5 Disabling the SMCs on the Fly
If an SMC is not needed for a period of time, it may be disabled and re-enabled later. In this
case, a sequence of operations is followed.
This sequence ensures that any buffers in use will be properly closed and that new data will
be transferred to/from a new buffer. Such a sequence is required if the parameters that must
be changed are not allowed to be changed dynamically. If the register or bit description
states that dynamic (on-the-fly) changes are allowed, the following sequences are not
required, and the register or bit may be changed immediately. In all other cases, the
sequence should be used. For instance, the baudrate generators allow on-the-fly changes.
7-274
To extract data from a partially full receive buffer, the CLOSE Rx
BD command may be used.
Freescale Semiconductor, Inc.
For More Information On This Product,
MC68360 USER’S MANUAL
Go to: www.freescale.com
NOTE
MOTOROLA