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Dealing with Netlist Changes

A project in XJDeveloper contains many lists of devices and nets in the circuit, broken down into different categories. These lists are referenced by device reference and net name. This means that when a new version of a board is created with a changed netlist, XJDeveloper needs to update the project with the new device and net names to allow the devices to be tracked and identified. The Revisions feature in XJDeveloper allows you to take an existing project and create a modified copy using new netlist, BOM and schematic data, whilst also carrying over most of the device categorisations. This will save time by reducing the number of devices which you need to categorise manually.

To achieve this, Revisions analyses the design data to attempt to map devices and nets in the original setup to their equivalent in the new netlist, even if their reference designators have changed, and then guides the user through confirming these updated assignments to ensure that they are all correct.

  • If your netlist changes only consist of additional device references, Revisions does not need to be used – the netlist can just be updated in a copy of the project, and new devices added through the Categorise Devices screen in XJDeveloper. Revisions helps with changes to device identifiers and netlist names.
  • If the netlist is unchanged, but devices have been added, removed, or their values modified then we recommend using Variants instead of Revisions.

Revisions uses a wizard to guide you through the process in a logical manner, minimising effort and helping you to catch all modifications. As changes are made or confirmed, the wizard will re-analyse the netlist, potentially finding new matches or asking additional questions.

The revision mapping is done by analysing data in the BOM, and connectivity between devices. For example, a CPU is typically very easy to match because it is a distinctive device on a board with a distinctive number of pins and will be connected to specific other devices, such as RAM chips, making it a unique match, even if the device reference has changed. Once these major components have been mapped, there is a basis for identifying many of the nets. From there, simpler devices such as resistors or LEDs can be identified.

Making a revision involves following a similar process to creating a new project, however the revisions wizard will perform as much of the work for you as it can. Nets and devices will be categorised where possible, however if major changes have been made, some manual intervention may be required. You can make these updates through the wizard interface, or through the normal XJDeveloper screens, whichever you prefer.

Before starting on a revision, please ensure that you are familiar with the process of setting up a project from scratch. This guide concentrates on how creating a Revision differs from setting up a new project.

Overview of the Process

There are several steps to run through in creating a revision:

  1. Open the original project you wish to base the revision on.
  2. Choose where to create the revised project.
  3. Import the various data files for the revised board(s) – this will include the netlist and may include the schematic and the BOM.

At this point, the Revisions wizard can begin to analyse the data, and match up the devices and nets on the boards. This is shown through the Revision Checklist, and as you work through the checklist stages, you will be guided through the process, showing the levels of confidence in each match:

  1. Checklist stage 1: Check the unfitted rules to make sure they still apply to the new board.
  2. Checklist stage 2: Check the power and ground nets have been assigned correctly.
  3. Checklist stage 3: Check the JTAG chain is properly configured.
  4. Checklist stages 4-10: Check any connections between different boards and that all devices have been correctly identified.
  5. Categorise any new devices which were not part of the original project.
  6. Checklist stage 11: Check the test files to ensure that all device references are valid.

As you work through these steps, you will have an opportunity to check any device assignments which the wizard has made automatically, confirm choices where confidence wasn’t high enough to automatically assign, and also add in any devices where no match was found from the original project.

  1. Checklist stage 12: When you are ready, Complete the new project to split it off from the original version.