Intel® Quartus® Prime Pro Edition User Guide: Debug Tools

ID 683819
Date 10/02/2023

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8.5.3. Using the SLD Service

The SLD Service shifts values into the instruction and data registers of SLD nodes and captures the previous value. When interacting with a SLD node, start by acquiring exclusive access to the node on an opened service.

SLD Service

set timeout_in_ms 1000
set lock_failed [sld_lock $sld_service_path $timeout_in_ms]

This code attempts to lock the selected SLD node. If it is already locked, sld_lock waits for the specified timeout. Confirm the procedure returns non-zero before proceeding. Set the instruction register and capture the previous one:

if {$lock_failed} {
set instr 7
set delay_us 1000
set capture [sld_access_ir $sld_service_path $instr $delay_us]

The 1000 microsecond delay guarantees that the following SLD command executes at least 1000 microseconds later. Data register access works the same way.

set data_bit_length 32
set delay_us 1000
set data_bytes [list 0xEF 0xBE 0xAD 0xDE]
set capture [sld_access_dr $sld_service_path $data_bit_length $delay_us \

Shift count is specified in bits, but the data content is specified as a list of bytes. The capture return value is also a list of bytes. Always unlock the SLD node once finished with the SLD service.

sld_unlock $sld_service_path