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Documentation of an Electronic Product

The word documentation itself sounds boring and indicates only clerical type of work. All technical people tend to do experiments but neglect documenting them or leave the job for nontechnical people. Even if any certification is not required documentation is very important. Various types of documentation can be described but here documentation related to an electronic product is discussed.

Documentation is very well used to transfer information and store/retrieve information. Hence each document is associated with it's information content. Many times a document lacks information that is, it is incomplete or the contents are ambiguous means contradicting to some other document.

While documenting; certain principles are to be followed such as document should be made by keeping in mind that will be using it. Best way is to imagine in the position of the user.

A document need not be only a written matter, it can be a text, a circuit diagram, an engineering drawing, a table, a list, a data sheet, a flow chart, a rough sketch etc.

Each document should contain complete information, and very importantly; the date of preparation of document or of modification.

Generally following documents are very important for an electronic industry.

1 : Design document .

2 : Production documents .

3 : User's manual.

4 : Installation instructions.

5 : Servicing manual.

6 : Periodic maintenance guide.

7 : Test procedures.

8 : Test reports.

and so on.

But the most important are

1 : Design document : many rough notes or documents are included; meaning the

document need not be drawn on a computer or by a draftsman. It contains the step by step

progress of all parts of design, that is electronic design, industrial design, software designs.

A very essential but neglected part is date on each paper.Basic reasoning behind selection of the

component, circuits, process, values etc. Is the major content of this document.

Use : it's use is

a) As, design is a group activity; it should always be person independent. This document makes

it so.

b) The same design can be used after some days when the task should not be repeated again.

The reasoning for selection of right component or rather rejection of wrong component helps a

lot.

2 : Production document : this document should contain all the information to produce a

product on large scale, and final drawings or documents , which are issued by, design

department.

Use : Faultless method of producing a product on a large scale.

3 : User's manual : it is a complete user's guide and includes installation, theory of

operation, operating instructions, periodic maintenance guide, servicing manual etc.

Use : the handling of the equipment.

Each of the three documents, we refer to them as main documents contain explanatory text

with sub-documents. Sub-documents and their explanation will depend on the organisation and

activity; but they can be as follows.

[1] Related to circuit / PCB.

(1) Circuit diagram : circuit diagram of the PCB.

(2) Wiring diagram : wiring diagram of the system.

(3) Component list : component list of PCB or system.

(4) Component layout : component layout of PCB (ident) or system.

(5) Part list : purchase list of PCB or system.

(6) Drilling details of PCB.

(7) Artwork of PCB.

(8) Films of PCB.

(9) Connector details.

(10) PCB layout.

(11) Block diagram of the complete system.

[2] Mechanical drawings.

(1) Mechanical assembly drawing of the system.

(2) Drawing of piece/s.

(3) Installed system drawing.

[3] software.

(1) Software structure diagram.

(2) Software listing (high level / assembly level).

(3) Software flowchart.

(4) List of memory allocation.

[4] Testing.

(1) Test procedure.

(2) Test tables.

(3) Test results.

[5] General.

(1) Assembly structure diagram.

(2) Special instructions.

(3) Specifications.

(4) Installation procedure.

(5) Proceeding index.

And any other document that is suitable for the system and the organisation.Each of the above document has a definite purpose. The documents should contain standard information (which is decided) and a standard formats. Hence in a document format and information content is

to be standardised.

Format :

A major part of format is the name block. The name block will be a standard block for each of

the above documents. Its contents and layout can vary from organisation to organisation.

Generally following information is necessary in name block. 1) name of the organisation, 2)

first or third angle projection sign, 3) drawn by, 4) drawn on date, 5) checked by, 6) checked on

date, 7) modification number, 8) modified by, 9) what is modified, 10)name of the document, 11)-

document number. 12) page number of number of pages.

Paper size :

Another important criteria is the size of the paper which is rarely followed in small and medium scale organisations. The general industry standard is A4 to A0. A0 is the maximum drafting table size. Its area is 1 sq. Meter and one side is ? times the other. Hence size of A0 is 1188mm * 840 mm. A1, A2, A3, A4 are half of the maximum dimension side of the previous one, and in illimeters are 840 * 594, 594 * 420, 420 * 297, 297 * 210 respectively. The folding methods to put them in a file is well defined. Because of the standard paper sizes, document is standardised, it ooks neat and clean, it is unambiguous, purchase and storage of papers and documents is asier.

Numbering a document :

It forms one important aspect of the document. A document can be identified by a name, but anaging the documents is required to be done and can be very well done by using the document number.A document number can be designed or formatted to suit the needs of the organisation. But in general it should have a) project / product identification, b) assembly / sub-assembly code, c) type of document, d) revision number. Numbering can be made much easier using an ssembly structure diagram. Structure diagram is a very useful concept in design of a system or software etc. It is a tool in top down design approach. In short, in a top down design approach; the system as a whole is viewed first and then broken into assemblies and sub-assemblies. At a time one can concentrate on only one sub-assembly and its interaction with other subassemblies at that level only. Same approach is very useful in software design also. The same structure diagram can be used and assemblies and sub-assemblies can be identified. Once they are identified, each assembly can have documents as in the list of sub-documents.

The main document will be just the compilation of all these documents with the help of

explanation in text wherever necessary.

Information content:

As we know that in a document; information content is a very important aspect; it should be

very clear that what information should a document contain. Hence for each document identified;

we can specify required information content apart from standard name block.

Information content of each document. A single paper of each document is preferable. The

organisation can decide its own information contents; following is the sample content but an

organisation can suitably modify by adding or deleting some contents.

In format of the sheet, name of the document, code of the document (as in brackets), it’s use,

information content of the document, format of lists wherever required and reference i.e cross

references. Completely filled name block will be a standard feature.

Section 1 : related to PCB/circuit as whole.

1) Circuit diagram : (CD)

Use : PCB layout, artwork, for trouble shooting, users manual, assembly and r&d.

Information : 1) all symbols drawn from the standard symbol drawing which will be

updated as and when required. 2) component numbers as per final component layout or component

assembly. (R1, IC1 etc.). 3) component values with complete specification as far as possible. 4)

unused gates to be shown: in short all pins used or unused are to be shown in the circuit diagram.

5) description of connectors. 6) all test points to be shown and numbered. 7) no component should

be missing including decoupling capacitors, jumpers. 8) any other information can be added for

example jumper meaning, port addresses etc.

Refer : component list, artwork.

2) Wiring diagram : (WD)

Use : assembly, testing, installation, trouble shooting.

Information : 1) wiring shown should be related to physical parts. 2) connector details as

pin numbers and types are necessary. 3) color code of each wire if any. 4) size of each wire. 5)

number put on ferrul, signal name.

Refer : harness wiring diagram including it's lengths etc.

3) component list : (CL)

Use : R & D, testing, formulation of part list.

Information : 1) component number as on circuit diagram as well as component layout or

assembly diagram. 2) complete description. 3) company part number. 4) this list should have one

component written on one line. 5) remarks for alternatives or special instructions.

Reference : circuit diagram, wiring diagram, component layout, part list, structure

diagram.

4) Component layout : (CY)

Use : PCB assembly, PCB testing, trouble shooting.

Information : 1) all component numbers in sequence either horizontal or vertical; to be

fixed up. 2) back annotated to circuit diagram. 3) mechanical fixing if any, should be clearly

shown. 4) size and shape of PCB. 5) all component outlines should be as per actual dimensions as

far as possible. 6) component number as per standard circuit symbols. 7) silk screen can be a

subset of this document.

Refer : circuit diagram, component list, drilling details.

5) Part list : (PL)

Use : purchase, production planning and inventory control.

Information : 1) part number. 2) component numbers 3) full description with make and

it's options. 4) supplier name. 5) quantity per subassembly or assembly whichever is preferable.

6) location in stores. 7) remarks.

Refer : assembly structure diagram, circuit diagram and component list.

6) Drilling details : (DD)

Use : PCB manufacturing.

Information : 1) clear indication of drill size. E.g. 1.1mm etc. 2) mention after or before

pth. Normally after pth. 3) standardised coloured codes can be used. 4) view from which side. 5)

mention non-pth holes, such as mounting holes. 6) PCB number.

Refer : component layout.

Note : it can be drawn on pad master or xerox copy of one side of PCB artwork.

7) Artwork : (AW)

Use : PCB manufacturing.

Information : 1) PCB number normal or reverse as per side of PCB. 2) revision of artwork.

3) component side , solder side or layer number. 4) exact PCB dimensions in 1:1. 5) which side

to match while taking films. 6) matching pads.

Refer : circuit diagram, component layout, drilling details.

Note : normally done in 2:1 scale; if very small tracks or components are present then

larger scale is preferable.

8) Films : (FM)

Use : PCB manufacturing.

Information : 1) PCB number normal or reverse as per side of PCB. 2) revision of artwork.

3) component side , solder side or layer number. 4) exact PCB dimensions in 1:1. 5) which side

to match while taking films. 6) matching pads.

Refer : circuit diagram, component layout, drilling details.

9) Connector details : (CN)

Use : wiring of the system.

Information : 1) connector description. 2) pin numbers as on connectors and it's signal

names.

Refer : wiring diagram.

10) PCB layout : (LY)

Use : PCB artwork if manual artwork.

Information : 1) view from which side. 2) layout side. 3) use of different colours (like

red and blue pencils) for different sides. 4) use pencil (black) for component outlines drawn on

same inch grid sheet.

Refer : circuit diagram, component layout.

11) Block diagram : (BL)

Use : explanation of complete system.

Information : 1) complete system block diagram explaining all functional aspects of the

system and of each block.

Refer : system specifications.

Section 2 : related to mechanical drawings.

1) Mechanical assembly : (MA)

Use : assembly, trouble shooting, disassembly.

Information : 1) various subassemblies and part indicated.2) all fastenings including

screws, nuts, welded joints etc. To be indicated. 3) sectional view to be shown if required. 4)

more than one drawing if opening and closing or back view is important. 5) subassembly

named. 6) reference drawing of subassembly. 7) material used. 8) all outside dimensions. 9)

tolerances of

dimensions. 10) drawing to what scale.

Refer : part list, component list, wiring diagram.

Note : isometric as well as orthographic drawings.

2) Drawing of piece : (MP)

Use : fabrication of cabinet or enclosures.

Information : 1) dimensions with tolerances. 2) material. 3) to scale drawing. 4) any

special instruction. 5) drilling and tapping details.

Refer : assembly drawings.

Note : if 19" rack is used then mention manufacturer and it's code etc.

3) Installed piece drawing : (MI)

Use : installation.

Information : 1) detailed installed piece. 2) if installation options are more then

indicate.

Refer : installation procedure.

Section 3 : Firmware / software .

1) Software structure diagram : (SS)

Use : writing and understanding software.

Information : 1) main modules. 2) sub-modules. 3) functions in brief. 4) subroutine name if

any.

Refer :

2) Software listing (high level) : (SH)

Use : analysis, debugging, hard back up.

Information : 1) latest modification done with date and what is modified. 2) clear

comments indicating function of the statement. 3) various variables used and their functions.

4)other files required such as h, lib, c, asm, tbl etc. 5) compiler user with it's version.

Refer : structure diagram, flow chart.

3) Software listing (assembly level) : (SL)

Use : analysis, debugging, hard back up.

Information : 1) cross assembler, 2) processor's name. 3) programme or subroutine name.

4) it's function. 5) called by. 6) calls. 7) destroys registers and memory locations. 7) i/o

information e.g. I/o line if port then it's description. 8) memory labels and descriptions. 9)

meaningful comments. 10)modifications details as date, what, by. 11) frozen software date. 12)

version number.

Refer : structure diagram, flow chart.

4) Flow chart : (SF)

Use : analysis and understanding software.

Information : 1) flow of the software using standard flowchart symbols. 2) the flow

should be bug free and single entry single exit type. 3) sub routine names.

Refer : software listing.

5) List of memory allocation : (SM)

Use : debugging and understanding old softwares.

Information : 1) labeled memory locations. 2) addresses. 3) any other important remark.

Refer : software listing.

Section 4 : general :

1) Assembly structure diagram : (GA)

Use : understanding the system and assembly of the system.

Information : 1) sub-assembly, assembly, component number as used for the numbering of

the drawings. 2) inter-relation between various levels.

Refer : assembly drawings, wiring diagram.

2) Special instructions : (GI)

Use : any type of special instructions.

Information : 1) clearly mentioned special instructions.

Refer :

3) Specifications : (GS)

Use : clear view of what is to be designed (before designing) and what is

being offered to the user.

Information : 1) power supply. 2) inputs. 3) outputs. 4) mechanical specifications. 5)

environmental conditions. 6) EMI / RFI conditions. 7) standard used. These should include

details such as nature, amplitude, tolerances etc.

Refer :

4) installation procedure : (GP)

Use : correct and easy installation at site.

Information : 1) tools required. 2) equipments required. 3) manpower required. 4) step by

step procedure of mechanical and electrical installation.

Refer : wiring diagram, drawing of installed system, test procedure.

5) proceeding index : (GN).

Use : Simpler method to find what happened, when. Ease of searching for r & d results.

Ease of reporting in brief; which is person independent. Keeping track of the project.

Information : 1) daily report; hence date. 2) one or two lines on important events related

to the project only. As it is only an index, detailed information is in the file.

Refer : Detailed information in the file.

Note : As it is required to be shown to a team leader and higher authorities;

the format includes place for signature of team leader as well as r & d chief.

Section 5 : testing.

1) Test procedure : (TP)

Use : Testing the product (qc)

Information : 1) circuit / wiring diagram of test set up. 2) instruments used with make,

model number and serial number. 3) step by step test procedure. 4) reference document for

acceptance norms. 5) if jig is used then reference document of the jig.

Refer : Test tables.

2) Test tables :(TT)

Use : Testing assemblies and sub-assemblies.

Information : 1) component / sub assembly/ assembly to be tested. 2) reference of test

procedure. 3) acceptance norm. 4) 100% or sample % test. 5) standard's reference. 6) reference

drawing numbers required for testing. E.g. If PCB is being tested; as per test points; then PCB

component layout.

Refer : test procedure.

3) Test reports : (TR)

Use : storing test reports and analysis of failures.

Information : 1) name of component / sub assembly/ assembly to be tested. 2) supplier

name. 3) challan number. 4) quantity received and checked %. 5) as per test table readings taken.

6) accepted / rejected with reasoning. 7) action taken. 8) remarks.

Refer : test procedures and test tables.

Contents of main documents

1) Design document : there is no hard and fast rule; but following is just the guidelines on

how it can be done. One can adopt other methods as well; as far as it fulfills the need of the

document.

This document can be divided into various sections such as 1) general, 2) electronics design,

3) industrial (mechanical) design, 4) mechanical design, 5) software details, 6) data sheets.

1) General : 1) how marketing department feels the need of the system. 2) detail data sheets of

existing product/s either abroad or local. 3) any write-ups in magazines etc. 4) who is the user. 5)

what is the market segment? 6) a small design market survey of the user. 6) final draft of

specification as in the format of specifications. After this step; one should always start for

designing. Any additions or deletions or changes in above should be added. 7) structure diagram,

rough sketch of the system. 8) standard available.

2) Electronics design : 1) design of electronic sub-assemblies, 2) their specifications, 3)

selection criteria for various parts,4) various tests carried out; choices of circuits, test reports and

reasons for selection or not selecting the circuit. 5) various problems found and their

solutions, 6) information passed to layout person along with instructions and component list, 7)

final circuit diagram. 8) layouts, artworks, drilling details, part lists 9) test procedures, etc. 10)

standards used.

3) Industrial design : 1) design of mechanical sub-assemblies, 2) their specifications, 3)

selection criteria for various parts, 4) rough sketches before selecting size and shape, 5) PCB

dimensions finalised, 6) reasons for selection and non-selection and changes etc. 7) standards

used, 8) finish, 9) material used, 10) final drawings are to be added.

4) Mechanical design : for system as a whole if any mechanical parts are involved then 1)

design of mechanical sub-assemblies, 2) their specifications, 3) selection criteria for various

parts, etc.

5) Software : 1) structure diagram, 2) flow chart, 3) rough work done, etc.

6) Data sheets : 1) all related data sheets or their xerox copies.

2) production document : The document should tackle each sub-assembly separately and

hence it will have various chapters depending on level of assembly / sub assembly. All drawings

will be final; when they are added to this document.

1) Overall system : 1) mechanical assembly drawing, 2) structure diagram, 3) component list of

complete system, 4) part list of complete system.

2) Chapter 2 onwards should start from lowest level subassembly. If PCB is the subassembly;

PCB circuit diagram, component layout, component list, part list, test procedures,

test tables. If mechanical fabricated then, all drawings of piece, test procedures, test tables,

development drawings etc. If required. If electrically assembled then, component list of subassembly,

part list of sub- assembly, wiring diagram, connection details, instructions of

sequence of

assembly and test procedures, test tables.

If mechanical assembly then, component list of sub-assembly, part list of sub- assembly,

instructions of sequence of assembly and test procedures, test tables for final product, test

procedures, test tables, and the location to put 'OK' sticker.

3) User's manual : This involves written text along with other documents. The text is equally

important. This is written by considering the user's level of knowledge. For example in case of

consumer products the language will be very simple and thus any user can understand it; as user

oriented product may have a manual in various languages. Hence user's manual will also vary

from product to product.

Following is a suggested format of user's manual for an industrial product.

Chapter 1 : Introduction.

1.1 : Introduction : introduction of the product, general and non-technical, a photograph/

drawing of installed product.

1.2 : Specifications : attach document.

1.3 : Theory of operation : block diagram, text explaining each block.

Chapter 2 : Installation.

Manpower required, tools required, material required, connection diagram, steps of installation

etc. Can be divided into sub parts.

Chapter 3 : Operating instructions.

Front panel drawing and associated explanatory text on how to use a system in detail. Displays

and their meanings etc. Can be divided into sub parts.

Chapter 4 : Maintenance.

4.1 : Preventive maintenance : manpower required, tools required, equipments required,

connection diagram, step by step procedure.

4.2 : Trouble-shooting : manpower required, tools required, equipments required,

connection diagram, step by step procedure.

Chapter 5 : Calibration : manpower required, tools required, equipments required, connection

diagram, step by step procedure.

Chapter 6 : Test reports : certificates of quality assurance and proof that the product is tested,

reply cards, other products and their functions.

Conclusion : These three documents are sufficient for an industry.

Documentation is not at all difficult and ample use of computer makes it much more easier.

What requires is only determination and will. Once created; it will help in reducing all troubles,

which occur mainly because of information gap.

Documentation is a habit and every person related to industry should have it.

Addenda on 14/4/09.

A product means a hardware or software product. It can be a simple product like a pen drive or a

complex one like Automated test system.

A document can be in any form. Hard form like print form, or soft form like audio, video, files etc.

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