CN7221 Datasheet, PDF (5/18 Pages) Conexant Systems, Inc – Home Networking Physical Layer Device with Integrated Analog Front End Circuitry

Home Networking PHY with Integrated AFE
System Signals
The system level signals provide hardware level
initialization, configuration and status indications from the
device. They are shown in Table 1.
The HLAN_OSC pin is the 60 MHz clock input pin.
The HLAN_IRQ signal is an active-low interrupt signal
intended for use as a level-sensitive interrupt to an external
processor. All interrupt sources are maskable and capable
of being stimulated through software via the ISR and IMR
programmable registers.
Signal
HLAN_RESET#
HLAN_IRQ#
HLAN_OSC
Table 1. System Signals
Description
Asynchronous system reset
Active low processor interrupt
60 MHz oscillator input
LANfinity™ CN7221
Seven Wire Serial (7WS) Interface
Signals
The 7-Wire serial interface provides the digital interface to
the Ethernet MAC.
The seven signals that comprise the 7WS are
HLAN_TX_CLK, HLAN_TX_EN, HLAN_TXD,
HLAN_RX_CLK, HLAN_CRS, HLAN_RXD, and HLAN_COL.
Of these, only HLAN_TX_EN and HLAN_TXD are inputs to
the PHY; the other five are outputs from the PHY. These
signals behave differently depending on which operation is
currently happening in the PHY. The operations of the PHY
are as follows:
• Idle (no activity in either direction)
• RxPKT (receiving data)
• TxPKT (transmitting data).
The subsequent subsections analyze each 7WS-related
state of the PHY in detail.
Table 2. 7WS Interface Signals
Signal
Description
HLAN_TX_CLK
Transmit clock
HLAN_TX_EN
Transmit enable
HLAN_TXD
Transmit data
HLAN_RX_CLK
Receive clock
HLAN_CRS
Receive carrier sense
HLAN_RXD
Receive data
HLAN_COL
Collision (active high)
Idle State
HLAN_TX_CLK
HLAN_TX_EN
HLAN_TXD
HLAN_RX_CLK
HLAN_CRS
HLAN_RXD
HLAN_COL
HLAN_RX_CLK and HLAN_TX_CLK are synchronized to the same phase. All other signals are inactive. The two clock signals
toggle low for 116.7ns and high for 466.7ns, for an overall period of 583.3ns (about 1.7MHz).
LAN-056, Rev. A
Conexant
5
PROPRIETARY INFORMATION