314 Hardware Reference Manual
Intel® IXP2800 Network Processor
Media and Switch Fabric Interface
8.9.6 Transmit State Machine
Table 1 14 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 11 4.
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.