Section 20 Ethernet Controller (EtherC)
Rev. 1.00 Mar. 12, 2008 Page 788 of 1178
REJ09B0403-0100
20.5 Usage
Notes
20.5.1
Conditions for Setting LCHNG Bit
Even if the level of the signal input to the LNKSTA pin is not changed, the LCHNG bit in ECSR
may be set. It may happen when the pin function is changed from port to LNKSTA by PCCRH2
of the PFC or when a software reset caused by the SWR bit in EDMR is cleared while the
LNKSTA pin is being driven high.
This is because the LNKSTA signal is internally fixed low when the pin functions as a port or
during the software reset state regardless of the external pin level.
Clear the LCHNG bit before setting the LCHNGIP bit in ECSIPR not to request a LINK signal
changed interrupt accidentally.
20.5.2
Flow Control Defect 1
Once a PAUSE frame is received while the receiving flow control is enabled in full-duplex mode
(the RXF bit in ECMR = 1), each time when the local station receives a normal unicast frame
(non-PAUSE frame without a CRC error), the TIME parameter specified by the PAUSE frame
that has been previously received is incorrectly applied. As a result, unnecessary waiting time is
generated to slow down the transmission throughput. The TIME parameter value is maintained
until another PAUSE frame is received.
This defect can be prevented if the destination station supports the function to transmit the 0-time
PAUSE frame as the same as this LSI does. Enable the use of 0-time PAUSE frame in this LSI
(the ZPF bit in ECMR = 1) before the 0-time PAUSE frame is received from the destination
station. This clears the TIME parameter incorrectly maintained in the EtherC and prevents the
unnecessary waiting time for transmission to be generated.
20.5.3
Flow Control Defect 2
When a PAUSE period is generated while the transmitting/receiving flow control is enabled in
full-duplex mode (the TXF/RXF bit in ECMR = 1), non-PAUSE frames are waited for
transmission (this is a normal operation) whereas PAUSE frames are incorrectly waited for
transmission. The transmission of non-PAUSE frames in a PAUSE period is prohibited, though
the transmission of PAUSE frames is enabled in IEEE802.3.
When a PAUSE period is generated by the request from the destination station (that is, a PAUSE
frame is received from the destination station), the load of the destination station is high and that
Summary of Contents for H8S Family
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Page 70: ...Section 1 Overview Rev 1 00 Mar 12 2008 Page 22 of 1178 REJ09B0403 0100...
Page 108: ...Section 2 CPU Rev 1 00 Mar 12 2008 Page 60 of 1178 REJ09B0403 0100...
Page 116: ...Section 3 MCU Operating Modes Rev 1 00 Mar 12 2008 Page 68 of 1178 REJ09B0403 0100...
Page 152: ...Section 5 Interrupt Controller Rev 1 00 Mar 12 2008 Page 104 of 1178 REJ09B0403 0100...
Page 206: ...Section 6 Bus Controller BSC Rev 1 00 Mar 12 2008 Page 158 of 1178 REJ09B0403 0100...
Page 420: ...Section 9 14 Bit PWM Timer PWMX Rev 1 00 Mar 12 2008 Page 372 of 1178 REJ09B0403 0100...
Page 476: ...Section 12 Watchdog Timer WDT Rev 1 00 Mar 12 2008 Page 428 of 1178 REJ09B0403 0100...
Page 552: ...Section 14 CRC Operation Circuit CRC Rev 1 00 Mar 12 2008 Page 504 of 1178 REJ09B0403 0100...
Page 712: ...Section 18 I2 C Bus Interface IIC Rev 1 00 Mar 12 2008 Page 664 of 1178 REJ09B0403 0100...
Page 804: ...Section 19 LPC Interface LPC Rev 1 00 Mar 12 2008 Page 756 of 1178 REJ09B0403 0100...
Page 838: ...Section 20 Ethernet Controller EtherC Rev 1 00 Mar 12 2008 Page 790 of 1178 REJ09B0403 0100...
Page 964: ...Section 24 RAM Rev 1 00 Mar 12 2008 Page 916 of 1178 REJ09B0403 0100...
Page 1066: ...Section 25 Flash Memory Rev 1 00 Mar 12 2008 Page 1018 of 1178 REJ09B0403 0100...
Page 1098: ...Section 26 Boundary Scan JTAG Rev 1 00 Mar 12 2008 Page 1050 of 1178 REJ09B0403 0100...
Page 1226: ...Rev 1 00 Mar 12 2008 Page 1178 of 1178 REJ09B0403 0100...
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