Challenge: find twelve design faults

[Ezra278]

Each element in the circuit is labelled ( c1, c2...) There are twelve design faults can you find them ?
Q2 i one of them

 

[gophert]

Each element in the circuit is labelled ( c1, c2...) There are twelve design faults can you find them ?
Q2 i one of them

Yup, I count 12 design issues. Not exactly a "challenge" (boarderline stupid).

 

[Ezra278]

Can you list them? I couldn't find them all...

 

[gophert]

No, let's let everyone have a chance to see it.

 

[dknguyen]

I found 14, but that might be because of whether you count something as a single error or two separate errors. The 13th thing was a little bit ambiguous due to lack of info about where the connector was going, or maybe because I don't trust internal pull-ups.

 

[schmitt trigger]

In addition to the naive mistakes like inverted caps and diodes, why would anyone use a 144 pin microcontroller if all you are going to use is about a dozen ports? What a waste.

 

[dknguyen]

In addition to the naive mistakes like inverted caps and diodes, why would anyone use a 144 pin microcontroller if all you are going to use is about a dozen ports? What a waste.

Maybe they have code and PCB layout from somewhere else and don't want to redesign?

 

[schmitt trigger]

In other words, they are lazy enough to just copy and paste from other design, and insert some silly mistakes while doing so.

 

[Beau Schwabe]

There are a lot more than 12 ... I count at least 36

 

[MrAl]

Hi,

I didnt even look at the schematic yet, if that is what that is, all i had to do was read the other replies and i can see that there is only one mistake:
They hired the wrong guy for the job

 

[gophert]

Hi,

I didnt even look at the schematic yet, if that is what that is, all i had to do was read the other replies and i can see that there is only one mistake:
They hired the wrong guy for the job

I'm thinking he ask us to do his homework so he could spend more time at the pub. Or, he already spent too much time at the pub and NEEDED us To get it done for him.

 

[dontknowreally]

There's no such thing as a fault or a bug. They are just undocumented features to be discovered at a later date

 

[Ezra278]

Sorry for asking for help didn't realize this is a site only for experts....

 

[Beau Schwabe]

I didn't think this was asking for help.... it sounded more like a "Golf Challenge" or puzzle you already had an answer to. I found 36 issues, but could probably find more if I looked harder.

 

[Ezra278]

Anyone here can help me out, what are the fualts?

 

[Beau Schwabe]

Here is the schematic with the 36 potential problems... dots indicate nodes that are not connected in the schematic or wrong connections. Lines indicate a wrong component ... i.e wrong kind of MOSFET, backwards MOSFET, wrong schematic symbol, wrong diode direction, resistor value too low (EEPROM)

 

[dknguyen]

filler text

 

[Beau Schwabe]

dknguyen .... lol ... he'll need both of our drawings ... you found a couple of things I missed and vise versa

 

[dknguyen]

Yeah I think you found the oscillator issue though I don't entirely agree.

I thought it looked funny the first time I saw it but am not good with oscillators. I think C32 and C33 shouldn't be there. I think C28 AND C29 are required though. I also think the oscillator itself is completley wrong too...pins 1 and 3 should be going to the MCU. But maybe there is more than one way to wire an crystal to an MCU. I wouldn't know.

 

[Beau Schwabe]

C28 and C29 are required but they are too small .... 18pF is typical, however look at the datasheet on that oscillator part, it might have the proper caps built in. (Don't know didn't look myself). If so, then he wouldn't need any caps there. The two pins on the oscillator I have dots on should be swapped. C32 and C33 should be removed. It is nit picky I know, but there are several nodes left unconnected... if left to an auto router, the connections would not be made. That is the main significance there.