There have already been lots of replies, but I'll throw in my few comments...
:: Hi, Upto now I've been building simple little projects on breadboards. Now I'd like to try my hand at designing a pcb board with an MCU onboard and all. ::
Do you have any actual layout tools in mind? Although they all require the same basic skills, they all differ in implementation and difficulty
:: I have a couple of questions which have puzzled me.
1) Is the board designed first and then the software written for the MCU or is it the other way around. I had one old school electical engineer tell me the board is designed first whereas I thought the software and circuitry is prototyped in pieces first and then comes the completed schematic layout. :: In a perfect world (rarely realised) the board requirements are stated first (Someone mentioned a project manager - that's one option). If the requirements of the board are clear, the electrical design requirements are at least clearer. As noted, unless the board is for a single purpose or perhaps just a general purpose (with I/O connector positions, for example) it is *never*
a good idea to try and design the board without knowing what the software must do. Often, all the design functions (electrical, firmware software, layout) reside in one person. I don't know many electrical engineers who have not written significant amounts of code - they *want*
to know what the code must do.
2) How do board level designers (who may not know much about programming the MCU) know HOW to layout the board? Do they just look at application notes from the manufacturer and lay things out and get it right on the first shot!? :: It is the task of the electrical engineer to guide the layout person (who may in fact be that same EE). We do schematic capture (with lots of notes), generate netlists and footprint requirements and pass them to the layout person with our notes. It is not unusual for the EE to sit with the layout person to deal with 'special' areas of the board. As to HOW to lay out the board - practise, practise, practise. A healthy does of aptitude helps, though.
We don't just 'look at app notes', although that forms part of the design exercise. App notes live in a perfect, isolated world. We design their parts into a larger scheme, which requires us to know how to adapt the information in the app note to our current requirements.
As to getting it right first shot, that takes a lot of practise (luck helps) and is usually a function of the complexity of the board, although classic neophyte problems abound for even the simplest of units. I had 5 in a row completely correct (i.e. the prototype is the shipping unit) for very complex boards (varied between really small and tight to big and hairy). That's the exception although we always try to get it right. It's the gotchas (which is why you should read the datasheets and app notes thoroughly) that catch you. ::
3) Is it possible that a board level designer can layout a board without knowing anything about programming the chips onboard? :: If you are talking about the electrical designer, I would say *no*
except for the simplest of devices. All newer processors and controllers have multi-use pins in these days, and a thorough knowledge of what the code/system requires is necessary to assign the correct pins to the correct board functions. If you are referring to the PCB layout person, then they don't necessarily have to know details, although we have to convey rules about the circuitry (which could be high currents, fast transients, high speed systems etc).
4) For surface mount chips (not in a DIP format where you can plop it into a breadboard for trial purposes), how do you go about trying them out before actually committing them to be produced on a PCB? :: Others mentioned making a prototype board first - I have done that myself. On other cases, the SMD board *is*
the prototype. For complex boards (or for analog sensitive boards) two different layouts will yield two different results, for an identical netlist.
5) When you want to incorporate a chip into your design and hook it upto other chips onboard, what is the first thing you go searching for? The datasheet or...? How can you be sure it will work in harmony with what's already onboard (i.e. all the pin connections are correct) :: The datasheets, application notes, tecchnical articles from the device manufacturer. I also call the local FAEs to see if they have reference designs.
:: I got a few more questions but I'll stop here for now.