Users Guide: Network Microcontroller Supplement User Manual

High-Speed Microcontroller User’s
Guide: Network Microcontroller
Supplement
185
Figure 22-12. Transmit Flow Diagram
CPU
Load transmit data buffer memory (MOVXs)
Write BCUD SFR
(Data buffer size/location)
1) msbyte of 11-bit transmit buffer byte count [00–06h]
2) lsbyte of 11-bit transmit buffer byte count [00–FFh]
3) Starting page of transmit buffer [00–1Fh]
Write BCUC SFR
With transmit request command:
BCUC.3-0 Command
0100 Transmit — Normal
0101 Transmit—No zero-padding of data
0110 Transmit—No FCS appended
ETHERNET CONTROLLER
BCU
CPU RUNS OTHER
APPLICATION CODE
BCU services transmit request
1) Transmit attempt by MAC completes or aborts
2) Transmit status word written to the data buffer
3) Transmit interrupt flag (TIF) set to 1
Ethernet activity interrupt request (if enabled)
1) Read BCUC to find TIF = 1
2) Read transmit status word for packet handling
Maxim Integrated