Mailbox Client Intel® FPGA IP User Guide

ID 683290
Date 12/04/2023
Public

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Document Table of Contents

1.4.3. Timer Registers

Use timer registers to monitor and address incomplete transactions between host and the Mailbox Client IP.

Incomplete Command Transaction Error

When a host fails to send the last command word to the Mailbox Client IP or the system stops sending data before the last word, the incomplete command transaction error occurs. Timer 1 allows you to set a specific transaction time period to complete each command. When the timer's timeout occurs, ISR[4] is set to indicate the error. To recover the system, you must reset the Mailbox Client IP.

Table 8.  Timer 1 Register
Bit Fields Access Default Value 5 Description
31 Timer 1 enable R/W 0x0 Timer 1 period enable bit. The bit is enabled once.
  • 1: Enable timer 1
  • 0: Disable timer 1

If a time out occurs, the timer 1 register becomes disabled. You must apply the Mailbox Client Intel® FPGA IP reset.

To start the timer 1, you must re-enable it again.

30:0 Timer 1 period R/W 0x7FF_FFFF

When enabled, the timer counts down the specified period as the maximum number of clock cycles the system has not received a valid command.

The timer 1 starts the count down as soon as the transaction writes the first data word into the Command FIFO (base address +0).

The timer resets when the Mailbox Client Intel® FPGA IP receives complete command transaction, indicated by successfully writing the last word into the command last word register (base address +1). When the timer 1 resets itself, it returns to its default or other defined value.

SDM Backpressure Error

SDM typically backpressures while it processes commands and sends responses. The SDM backpressure error occurs when SDM backpressures for some time period not allowing you to write any data into the Mailbox fabric and SDM. The timer 2, by setting a specific wait time, allows you detect the long wait and take steps to recover your system. When a timer's timeout occurs, ISR[5] is set to indicate an error. Note that this is a fatal error received from SDM, possibly indicating a system error. Resetting the Mailbox Client won't recover the system.
Table 9.  Timer 2 Register
Bit Fields Access Default Value 6 Description
31 Timer 2 enable R/W 0x0 Timer 2 period enable bit. The bits is enabled once.
  • 1: Enable timer 2
  • 0: Disable timer 2

If a time out occurs, the timer 2 register becomes disabled. You must apply the Mailbox Client Intel® FPGA IP reset.

To start the timer 2, you must re-enable it again.

30:0 Timer 2 period R/W 0x7FF_FFFF When enabled, the timer counts down the specified period as the maximum number of clock cycles the system has not asserted ready high signal. The SDM backpressures commands sent by host to the Mailbox Client Intel® FPGA IP.
5 Resetting the Mailbox Client IP resets the timer 1 register to the default value.
6

Resetting the Mailbox Client IP resets the timer 2 register to the default value.