Electronics-Proteus Term Paper
The Proteus Design Suite is a Windows application software designed for the purpose of electronic circuit simulation, Schematic Capture and Printed Circuit Board (PCB) layout design. Common areas of application include digital simulations, such as microcontrollers and microprocessors. It is available in various configurations depending on the design size being produced and microcontroller simulation requirements.
Proteus integrates the ISIS software which is used to draw schematics and simulate circuits in real time. This simulation allows non-machine or rather human access during run time, therefore providing a real time simulation. ISIS has a wide range of components in its library. These include signal generators, measurement and analysis tools like oscilloscope, ammeter, voltmeter, probes for real time monitoring of the circuit parameters, several switches, displays, inductors, transformers, analog and digital integrated circuits, semi-conductor switches, relays, microcontrollers and sensors.
Also, integrated in Proteus is the ARES. This is specially applied in PCB designing and it has the features of viewing the designed PCB output in 3D along with its components. ARES offer designing capacity to up to 14 inner layers plus two outer layers. It is packaged with footprints of different categories like integrated circuits, resistors, headers, connectors and their respective discrete components. ARES offer auto-routing and manual routing options to the PCB Designer. The schematic drawn in the ISIS can be transferred directly into ARES.
While switching from ISIS to ARES, Proteus creates a net list with information regarding the pads interconnection. The information is presented graphically with green lines once the components are placed in PCB layout. These green lines are referred to as ratsnest. Ratsnest describe patterns a user gets on the screen when the pin to pin connections specified in the netlist are shown as single straight lines rather than copper tracking.
In the case where the auto-router module is used, ARES generates copper tracking only between pads having the ratsnest connection. Whereas in manual routing, ARES uses ratsnest to assist the user in routing process and cannot approve of connection being done between two pads that do not belong to the same net.
The Proteus was initially developed in Yorkshire, England by Labcenter Electronics Ltd and rolled out in English, French, Spanish and Chinese languages. The modern version called the Proteus Design Suite was known in its first version as PC-B and was written by the company chairman for DOS in 1988. Later in 1990, a second version was released and called Schematic Capture support with a port to the Windows environment. In 1996, SPICE simulation which is a mixed mode first got simulated into Proteus and thereafter followed by microcontroller integration in 1998. Shape-based autorouting and 3D Board Visualization are the major product updates done in 2002 and 2006 respectively. 2011 saw the addition of IDE for simulation and a support for high speed design was added in 2017.
In Proteus Design Suite, feature led designs are rolled out biannually while maintenance based service packs are released as demanded. The Proteus Design Circuit can be broadly categorized into its major components;
It is the core component in Proteus Design Suite significant in the simulation of designs and as the design phase of PCB layout project. It is therefore included with all the product configurations
Printed Circuit Board (PCB)
This is a circuit board with printed copper layout connections and has of two types; dotted PCB and layout PCB.
Dotted PCB has only dots embedded on its board therefore components are inserted or placed on these holes and attached with wires and soldering lids. Demerits of dotted PCB include risk of connecting improper pins and short circuiting.
Layout PCB is designed by first selecting suitable circuit designing software then designing the layout by etching the copper layout and soldering the components in their correct places. It takes less time to design and has no shortcomings witnessed in dotted PCB. Its design is also appealing. The PCB software that can be used in designing layout PCB includes Express PCB, Eagle PCB, PCB Elegance, Free PCB etc.
PCBs occur in layers; single layer, dual layer and multilayer PCBs. In single layer PCB, components are placed on one side and connections (tracking) on the other side. In dual layer, components lie on two sides and tracking also done on two sides.
Multilayer PCBs apply the use of several layers. Two of these layers are the top and bottom layers while the rest are inner layers. In Proteus, up to 16 layers can be designed, two serving as top and bottom ones and the remaining 14 being inner layers, each represented by its own unique color, including the two outer ones.
Dual layer PCBs are advantageously created by Proteus using the auto-router feature that automatically arranges the tracks without errors.
PCB Layout Printing
Printing is done in line with the desired layout to be achieved. The usual printing techniques applied include:
- Top copper layout printout which is commonly applied in dual layer PCB.
- Bottom copper layout printout applied for single layer printout. While using this method, the scale should be selected as 100% and rotation as X horizontal. Most importantly, reflection should be ‘mirror’ because after printing the layer on paper it is placed on copper board on the opposite side facing the copper layer.
- Top silk layer printout. This works in combination with bottom copper printout. The top silk layer prints components view. The reflection mode used is normal mode.
- Bottom silk layer printout used for dual layer PCB printing.
- Solder resistor layer printout specifically used for preventing short circuits. Reflection mode is mirror mode because the technique is same as bottom copper layout printout.
- Drill plot layout printing. This layer shows the position of drill and the hole size. Reflection mode is normal.
After printing, the next step is PCB itching meaning copper tracks layered on paper. It is carried out in the following steps:
- Take copper layered PCB board and cut according to requirement.
- Place the bottom copper layer printed paper on the copper board by facing the printed surface to the copper layer.
- Fix the paper on the board without moving it.
- Apply heat to the printed paper using preferably iron box or any other suitable heat source.
- Using a printing machine, spray carbon powder on the white paper while applying heat. The model is then scanned.
- Drop the board into water and remove the paper slowly while fixing the carbon layer on copper board.
- Drop the board into ferric-chloride liquid where the copper having carbon will react with ferric-chloride while copper without carbon will be dissolved.
- Clean the board with sand paper to erase carbon layer. The carbon layer will be completely removed, leaving a clean copper layer.
- Make appropriate holes by drilling according to drill position layer.
- Place proper components in their correct places then fix them to the board using soldering kit.
- Cut extra pins from the holes using a cutter. The circuit is then ready for use.
This is a simulation feature in Proteus that works by applying either hex file or debug file to the microcontroller section on the schematic capture, subsequently simulated along any analog or digital component connected to it. This enables wide range application of project prototyping in fields such as motor control, user interface (UI) designing and temperature control. It is a convenient training or teaching tool since it does not necessitate the use of a hardware.
Shape Based Auto-Routing
Proteus integrates an automated shape-based router that uses cost-based conflict minimizing algorithms which prove to maximize completion rates even at the most densely packed boards.
In order to command full control of the routing process, users possessing advanced feature set like the PCB Design Level 2 or higher can drive the router either by writing their custom routing scripts or by interactively keying in directly the routing commands. This opens up several additional features like the ability to route only specific highlighted areas and also additional flexibility such as the ability to specify the fanout direction or length.
In order to ensure correct timing at the signal receiver for high speed transmission, length matching of tracks becomes essential. Proteus integrates support for automated length matching of tracks using a simple select and a match user interface. This includes the ability to have track segments in multiple match groups required for routing topologies.
Usually, arrangement of the extra trace used in lengthening shorter routes, referred to as serpentine, poses much of a difficulty. The signal rise time, the frequency of the signal the requirements for via sited on the PCB are among the dependent factors that a PCB designer needs to consider in adjusting or constraining the serpentine height and width.
However, in Proteus, there is an inclusive single dialog form which handles and controls the topology of the serpentine. Depending on the timing budget of the user interface, absolute or relative tolerance for the length match can be adjusted.
Power plane support feature in Proteus is a user placeable polygonal regions within which inner boundaries are created automatically around the existing pads and tracking. It supports thermal reliefs and one can choose to hatch the polygons or fill them. Inner zones of the polygons also referred to as nested zones can be included while islands of unconnected copper suppressed. Computation is purely based on grid-less shape geometry and takes place in the background such that there is no interference in manual board placement for computationally intensive layouts.
Stitching and Shielding
This is an applied technique used to tie together larger copper sections on different layers significantly useful in keeping return paths short and reducing noise on the PCB. Planes can be automatically stitched in Proteus via a simple context menu command which gives the user control over via style and spacing as well as row offsets for the stitching pattern.
A via shield, also called picket fence can be added around the border of the planes using the same context menu command. This creates a single row of vias around the zones’ perimeters, helping to prevent electromagnetic interference with other nearby equipment.
To isolate signals of PCB operating at different frequencies, stitching and shielding technique can be used alongside high speed routes such as microstrip or stripline.
These are features often used at the connection point between track and pad to prevent drill breakout during board manufacture. When enabled in Proteus, teardrop connections will be made to all qualifying routes. Teardrops are automatically generated, updated and removed as the user places, edits and deletes routes during board layout designing.
The 3D visualization tool in Proteus provides a means of extruding a layout and view the board as it would appear in real-life. It provides both orbital and ‘fly by’ navigation options which are extremely intuitive and mouse controlled. The user is able to specify desired height plane corresponding to the board chassis which appears as a semi-transparent box around the board allowing a quick visual check for protrusions.
Proteus library comes equipped with 3D footprints and comprehensive support enabling creation of custom 3D footprints directly inside Proteus or by alternatively importing models via the standard STEP and 3D file formats. Direct output from the 3D viewer includes STEP, IGES, 3D DXF and STL.
Proteus also provides a full set of features for professional board manufacturing. The primary output format used is the Garber X2, which together with IPC-D-356 netlist and an optional assembly of drawings provides a complete representation of the PCB.
This an application module in Proteus used in adding documentation or written content to the project. It is a free form editor that enables a user to whatever notes in whichever style. The template system in project notes allows one to create, save and reuse formatted content. The project Notes module can be used interactively with other modules in the Proteus system. For example, one can link texts to real parts on the schematic or layout so that by clicking the link, the user is able to navigate to the part of the design or PCB. The user can also apply field codes to input design information such as author or revision number and the additional internal feature-the internal clipboard, makes it easy to copy and paste pictures from other Proteus models into the Project Notes module.
During the process of manual routing, Proteus counter-checks each track as placed and warns the user if any design rules, whether physical or electrical, is broken. One can apply full customization to the board constrains, by setting rules by physical region or a user drawn region on the PCB. A user can also apply a set of rules by electrical net class and if necessary combine the two to come up with even tighter constrains.
The design rule status and connectivity status have a live indication bar at the bottom of the Proteus. Clicking on either produces a report of missing or extra connections while double clicking on any entry on the list will zoom in to indicate the exact location of the error on the PCB.
The pre-production check runs prior to manufacturing output and is designed to be an automatic quality assurance check. It also checks power plain geometry and integrity through a separate code path and runs separate tests for common design mistakes.
Templates and Technology Data
Proteus layout module includes a comprehensive scheme in form of board templates and technology data where a user has the ability to create several templates in the face of one project and then initialize new layouts from it to preload all the configured information from it. A default set of Eurocard boards are provided as standard. A template file is basically a layout consisting of a board edge, mounting holes and other features together with a technology data set. This set includes design rules, net classes, layer stack up information, grids, units and board properties that can be applied directly to other layouts as well as when initializing a new project from the template.
This routing requires no rubberbanding (starting from the ratsnest lines). The user can place tracking in any way and Proteus will remove ratsnest lines as the connection is actually completed. During track placement, the route will follow the mouse cursor direction wherever possible while going around obstacles and obeying design rules of the project.
The user can re-route or delete any section of tracking. In case of thick tracks laid between obstacles like IC pads the route changes automatically change or made thin so as to maintain current design rules. Commands are provided to change thickness or layer of any section of tracking. To lay curved tracks, the user simply holds down CTRL key while dragging the mouse pointer.
Proteus comes with libraries that cover a wide range of through hole components including all of the common IC, transistor, diode and connector packaging types.
This module of Proteus is crucial in managing the PCB design workflow. It allows the user to inspect the components on a schematic grid-like view indicating parts with no packaging along with the placement status of each part on the said layout.
This module is also the platform for creating design variants. Once added, the user selects the variant to make it active and then changes individual part status to be fitted or not fitted. The design explorer has a search tab that plays the role of a filter on the parts used in the design, making the performance of bulk designs an easy task.
These provide a simple management method of multiple product configurations in a single schematic or PCB project. It is simply done by specifying the fitted or not fitted status of each component on a per variant basis, in which the users are also able to specify different properties for particular components in each design variant.
Proteus has the user interface managed by the Design Explorer which possesses columns for each variant, allowing the user to easily remove or add components for that product.
The system presented above shows a proposed design that can be used in an industrial setup. It has been programmed with a view of capturing the manufacturing process and to solve issues associated with it. Control of the conveyor system articulately captures automation along the line. Automation of the mechanical fan for air conditioning also brings in additional control features.
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Su, Bo and Li Wang. “Application of Proteus virtual system modeling (VSM) in teaching of microcontroller.” In 2010 International Conference on E-Health Networking Digital Ecosystems and Technologies (EDT), vol. 2, pp. 375-378. IEEE, 2010.