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314 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
Media and Switch Fabric Interface
8.9.6 Transmit State Machine
Table 114 describes the transmitter state machine by providing guidance in interfacing to the
network processor. The state machine is described as three separate state machines for SPI-4.2,
training, and CSIX-L1. When each machine is inactive, it tracks the states of the other two state
machines.
8.9.6.1 SPI-4.2 Transmitter State Machine
The SPI-4.2 Transmit State Machine makes state transitions on each bus transfer of 16 bits, as
described in Table 114.
Table 114. SPI-4.2 Transmitter State Machine Transitions on 16-Bit Bus Transfers
Current State Next State Conditions
Idle Control Idle Control
No data pending and no training sequence pending,
CSIX-L1 mode disabled.
Payload Control
Data pending and no training sequence pending,
CSIX-L1 mode disabled.
Training Training sequence pending, CSIX-L1 mode disabled.
CSIX CSIX-L1 mode enabled.
Payload Control Data Burst Always
Data Burst Data Burst Until end of burst as programmed by software.
Payload Control
Data pending and no training sequence pending and
CSIX-L1 mode not enabled.
Idle Control
No data to send or training sequence pending or CSIX-
L1 mode enabled.
Tracking Other State Machine States
Training Training Training SM not entering CSIX-L1 or SPI state.
CSIX Training SM entering CSIX-L1 state.
Payload Control Training SM entering SPI state and data pending.
Idle Control Training SM entering SPI state and no data pending.
CSIX CSIX CSIX-L1 SM not entering Training or SPI state.
Training CSIX-L1 SM entering Training state.
Payload Control CSIX-L1 SM entering SPI state and data pending.
Idle Control CSIX-L1 SM entering SPI state and no data pending.