Specifications

RX62N Group Ethernet Transmit and Receive Settings
4.1.2 32BOverview of ETHERC Transmitter
The ETHERC transmitter assembles transmit data into a frame and outputs it to the MII/RMII when there is a
transmit request from the transmit EDMAC. The transmit data is sent to the lines via the MII/RMII by the physical layer
transceiver (PHY). Figure 4.2 shows the state transitions of the ETHERC transmitter.
• 1. When the transmit enable (ECMR.TE) bit is set to 1, the transmitter enters the transmit idle state.
• 2. When a transmit request is issued by the transmit EDMAC, the ETHERC sends the preamble to the MII/RMII
after carrier detection and a transmission delay equivalent to the frame interval time. If full-duplex transfer, which
does not require carrier detection, is selected, the preamble is sent as soon as a transmit request is issued by the
transmit EDMAC.
• 3. The transmitter sends the SFD, data, and CRC sequentially. At the end of transmission, the transmit EDMAC
generates a transmission complete interrupt (TC). If a collision or the carrier-not-detected state occurs during data
transmission, it is reported as an interrupt source.
• 4. After the frame interval time elapses, the transmitter enters the idle state, and if there is more transmit data,
continues transmission.
Reset
TE set
FDPX
TE reset
Failure of 15
transmission
retries or
collision after
512-bit duration
Collision
Collision
Normal transmission
Carrier detected
Carrier detected
SFD transmission
Data transmission
CRC transmission
Transmission retry
processing*
1
Carrier
detected
Start of transmission
(preamble transmission)
Idle
Carrier not
detected
Carrier not
detected
Carrier
detected
HDPX
HDPX
Transmission
retry start
Transmission
halted
[Legend]
FDPX: Full-duplex
HDPX: Half-duplex
SFD: Start frame delimiter
Error detected
Error
Error
Error
Error
notification
Collision*
2
FDPX
Collision*
2
Notes: 1. Transmission retry processing includes both jam transmission accompanying collision detection and
adjustment of the transmission interval by the back-off algorithm.
2. Transmission is retried only when transmitting 512 or fewer bits of data (including the preamble and SFD).
When a collision is detected during transmission of more than 512 bits of data, only jam transmission occurs
and transmission retry using the back-off algorithm is not attempted.
Figure 4.2 ETHERC Transmitter State Transitions
R01AN0629EJ0101 Rev.1.01 Page 19 of 52
Mar 31, 2011