Motorola PowerQUICC II MPC8280 Series Reference Manual page 1336

Ethernet TxBDs
Table 36-11. Ethernet TxBD Field Definitions (continued)
Field Name
9 RL Retransmission limit. The transmitter failed (RET_LIM + 1) attempts to successfully send a message
due to repeated collisions. The Ethernet controller updates RL after sending the buffer.
10–13 RC Retry count. Indicates the number of retries required for this frame to be successfully sent. If RC =
0, the frame is sent correctly the first time. If RC = 15 and RET_LIM = 15 in the parameter RAM, 15
retries were needed. If RC = 15 and RET_LIM > 15, 15 or more retries were needed. The Ethernet
controller updates RC after sending the buffer.
14 UN Underrun. The Ethernet controller encountered a transmitter underrun condition while sending the
associated buffer. The Ethernet controller updates UN after sending the buffer.
15 CSL Carrier sense lost. Carrier sense is lost during frame transmission. The Ethernet controller updates
CSL after sending the buffer.
Data length is the number of octets the Ethernet controller should transmit from this BD
data buffer. This value should be greater than zero. The CP never modifies the data length
in a TxBD.
Tx data buffer pointer, which contains the address of the associated data buffer, can be even
or odd. The buffer can reside in external memory. The CP never modifies the buffer pointer.
36-30
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