Finally my prop module PCB!! Would appreciate any input, decoupling wiring, etc

Comments

• prof_braino Posts: 4,313

  2012-03-14 07:25 edited 2012-03-14 07:25

  rwgast_logicdesign wrote: »

  ... whether to put male headers under the board to plug into a bread board or female headers on the top to route jumpers to other boards easily.

  
  I worry that male headers on the bottom are asking for damage, as at least some part of the time it WON't be plugged into a breadboard.
• Leon Posts: 7,620

  2012-03-14 08:01 edited 2012-03-14 08:01

  They are used on other boards, such as the mbed and the LPCXpresso, and don't cause any problems.
• JonnyMac Posts: 9,236

  2012-03-14 08:38 edited 2012-03-14 08:38

  You have capacitors in series with the inputs of your regulators -- this is not what you want. Those regulators should be connected between the power inputs and ground.
• Duane Degn Posts: 10,588

  2012-03-14 09:22 edited 2012-03-14 09:22

  I had mentioned I had a board I used for prototyping with the Prop. I started a new thread so I wouldn't hijack this one.
  
  I just keep the male header plugged into some anit-static foam when I'm not using it.
  
  As Leon said, there are lots of boards with male headers on the bottom (though they are kind of a pain to store).
• Duane Degn Posts: 10,588

  2012-03-14 09:25 edited 2012-03-14 09:25

  Along with the caps Jon mentioned, your reset circuit has a problem. The reset from the Prop Plug should not go through the button.
  
  The button is an independent circuit that connects reset to ground.
  
  You'll want to use the schematic in the Propeller Education Kit (found in the "Help" menu of the Propeller Tool).
• rwgast_logicdesign Posts: 1,464

  2012-03-14 13:05 edited 2012-03-14 13:05

  Ok thank you guys, i will go back and review the problems listed so far and make the appropriate changes then repost. As far as adding the i/o pins to the bottom to plug into a bread board im not sure im going to do that, not really my main concern at the moment, ive already considered the drawbacks and if i were to use them i would be putting dip switches on the board to keep them from floating to ground, and keeping the pins sleeved with female sockets.
  
  Duane nice board, as for your thread and what you said about not making your own boards anymore because of the good selection available, I commpletely agree unless your doing it to learn hardware design. I acually just founds this last night http://www.mikronauts.com/cpumodule/ which is pretty close to what i had in my mind as far as my finished design, and ill probably be buying this as my main prop board for development, until my design is tweaked and to perfection.
  
  No one has seen any issues i may have with decoupling or anything? I know clusso and the boards on mikronauts use more caps im just not sue where i should be putting them, i think i need .1uf caps on the VSS pins but im not sure. Im also really not sure if all the eeproms are wired right, I spent alot of time trying to mentally picture how to hook the resistors up to the voltage and data lines, the two eeprom in parallel made it difficult for me to visualize the whole circut to fit my layout. Two other details im wondering about, what kind of diode should i use for polarity, and if using a 3.3v led do i need a resistor in front of it, if so wont this limit the current going to the eeproms?
• Duane Degn Posts: 10,588

  2012-03-14 13:23 edited 2012-03-14 13:23

  rwgast_logicdesign wrote: »

  and if using a 3.3v led do i need a resistor in front of it, if so wont this limit the current going to the eeproms?

  
  I just noticed your LED is in series with the rest of your circuit. You'd have the LED in parallel to the other devices. An 100 ohm resistor will be enough to keep most LEDs safe but you might want to use a larger value to not have the LED so bright.
  
  You really need to look at some other schematics. There are schematics available for most if not all the boards Parallax sells. They will answer a lot of your questions.
• JonnyMac Posts: 9,236

  2012-03-14 13:34 edited 2012-03-14 13:34

  You really need to look at some other schematics.

  
  For example, in this article you'll find the schematic for my original Propeller Platform.
  
  -- http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/prop/col/nvp0.pdf
• Duane Degn Posts: 10,588

  2012-03-14 13:41 edited 2012-03-14 13:41

  JonnyMac wrote: »

  For example, in this article you'll find the schematic for my original Propeller Platform.

  
  That's my que to make sure rwgast knows about all of JonnyMac's Spin Zone articles. PASM finally made began making sense to me from reading his articles.
• rwgast_logicdesign Posts: 1,464

  2012-03-14 14:36 edited 2012-03-14 14:36

  Ok well the schematics are updated to reflect the RST button and diffrent wiring for the vRegs. Ill fix the led problem a bit later. As far as schematics ive been going of the one for the GG prop platform the Propeller Proto board, and the simple dip diagram in the prop chip manual. Ill take a look at some others.
  
  Thank you guys for the second looks, most of the errors I made are becuase i chose to rewire things that way like the vregs and LED, but I didnt realize it was wrong. Im really worried about the eeproms and the caps too, i just remmbered I didnt do any decoupling on the eeprom chips.
  
  EDIT: O wow those schematics that were linked too are the ones from GG ive been using to help me out with the eeproms.
  EDIT: led wiring is now parallel? 100ohm resistor in series with led
• Duane Degn Posts: 10,588

  2012-03-14 15:20 edited 2012-03-14 15:20

  rwgast_logicdesign wrote: »

  Ok well the schematics are updated to reflect the RST button and diffrent wiring for the vRegs. Ill fix the led problem a bit later. As far as schematics ive been going of the one for the GG prop platform the Propeller Proto board, and the simple dip diagram in the prop chip manual. Ill take a look at some others.
  
  Thank you guys for the second looks, most of the errors I made are becuase i chose to rewire things that way like the vregs and LED, but I didnt realize it was wrong. Im really worried about the eeproms and the caps too, i just remmbered I didnt do any decoupling on the eeprom chips.
  
  EDIT: O wow those schematics that were linked too are the ones from GG ive been using to help me out with the eeproms.
  EDIT: led wiring is now parallel? 100ohm resistor in series with led

  
  The caps are still wrong on your voltage regulators.
  
  The EEPROMs look OK to me (except for the need for decoupling caps).
• rwgast_logicdesign Posts: 1,464

  2012-03-14 15:49 edited 2012-03-14 15:49

  Ok are the caps wrong or is the wiring wrong? After looking at the setup when rewired I realized the acuall caps were probably wrong, ie the cap values and the number of caps, but the connections are correct right? like if the caps were the right size and number that wiring scheme would work?
• JonnyMac Posts: 9,236

  2012-03-14 16:24 edited 2012-03-14 16:24

  You are still WAY off the mark. You have capacitors in series instead of parallel to ground as they should be. We've all pointed you to working references -- slow down, compare your schematic to the references, and learn from your mistakes.
• rwgast_logicdesign Posts: 1,464

  2012-03-17 01:52 edited 2012-03-17 01:52

  Ok so here is two diffrent schematics the first one being how interperet almost every prop schematic with two voltage regulator where the regs are connected in series the out of one going to vin of the next, which makes no sense to me, in my mind that sending an already regulated voltage to the regulator, which if this was a 5v and 3.3v system connecting the regs in series would work as long as the 5v was first, but it also seems like it would put unessisary load on the 5v reg. In my system I have two 3.3 regulators obviously connecting them in series isnt going to work since the second regulator would need more than 3.3v to power it. So my design and the way i understand how things work is the second schematic which will supply both regulators with unregulated voltage directly from the power source. I chose the cap sizes based on the data sheet so im thinking that shouldnt be a problem. Here is the schematics
  
  http://dl.dropbox.com/u/27653605/reg.bmp
  
  Ive also been reading alot of pcb design posts by cluso and saphiea, Im going to replace the .1uf decoupling caps with 4.7uf caps, apparently this is a better size especially when overclocking, JohnnyMac i am assuming you are the GG prop board designer, is this why you chose 4.7uf caps? Also everything im reading by good pcb designers and decoupling articles tells me i should be putting a 10uf cap in parallel with the decoupling cap(s?), im not sure if this means i need to wire the 10uf cap in paralell with the two 4.7 caps on the vdd pins or if i should be wiring a 10uf cap in paralell each 4.7 cap, that is, respectively, do i need two 4.7 caps and one 10uf, or two 4.7uf and two 10uf? Also im seeing people using tantalums for there 10uf, wouldnt a ceramic disc be better, the discs have better response time and lower esr than a tantalum right??
  
  The next question I have is from everything i have read all the overclocking problems with the prop stem from an unstable pll due to voltage switching, this is why all the decoupling caps are needed to stabilize the prop at higher frequencies. What effect would using a switching regulator have, something like this http://www.robotshop.com/dimension-engineering-de-swadj3-switching-regulator.html
• average joe Posts: 795

  2012-03-17 02:30 edited 2012-03-17 02:30

  Not to be rude, but it sounds like you need to work on something a bit simpler first. Honestly, start with the voltage regulators. RTFM! Get you're power supply right first, then get the prop and support circuitry going. I recommend using .1uf tantalum caps on the power supply pins. It looks like you're using a 40 pin dip. If you socket this, use a socket with an open bottom. This way the caps go under the chip. Also, keeping the clock lines SHORT and using ground fill is always a good idea.
  
  DONT replace those .1uf caps, if you feel you want bigger caps, put them in parallel with the .1uf caps. The .1uf "absorb" the high frequency content, the 4.7uf's absorb the lower freq. I basic DC electronics course would help you understand this quite a bit better. I highly recommend such a class if you are serious about making your own boards. Otherwise it's probably better left to the pros @ GG
• rwgast_logicdesign Posts: 1,464

  2012-03-17 06:17 edited 2012-03-17 06:17

  please dont give ill advice..
  there is no short circut protection when decoupling and tantalums have a bad habbit of lighting on fire when shorted... this may not be common but it is an issue. i would hate for my pcb to fall on something and start a fire. and ceramics have a much better response with less esr than tantalum. also if sephieha and gg use 4.7uf caps on the power power pins connected to a 10uf to round out the lower freq than im pretty sure they have there reasons.. all the gg boards and mikronaughts (im pretty sure thats sephia layout) are pretty hi quality so i wont question there findings and designs. i have taken basic dc theory, usually that does not cover digital electronics and decoupling, your to busy solving rc circuts and working ohms law a million times. also some of us dont have the money for classes so out of nessacity we do rtfm and self teach. apparently everything except my regulators were fine.. all im saying is im learning constructive critisim is welcome im always open to new things and backed ideas. but that was hardly helpfull or condtructive or even right..... please research tantalum caps look at there esr values and heat ratings then check out good ceramics with ceramics growing in capacity tants are becoming useless unless you dont wanna spend the nickel more for a 10uf disc. plz excuse my grammar its late and im typing on a cell
• JonnyMac Posts: 9,236

  2012-03-17 07:04 edited 2012-03-17 07:04

  JohnnyMac i am assuming you are the GG prop board designer, is this why you chose 4.7uf caps?

  
  I designed the original Propeller Platform board for my Nuts & Volts column; mine version used the 40-pin DIP variant. Originally there were two 0.1uF decoupling caps on the chip and later I bumped the cap on the crystal side to 4.7uF tantalum at the recommendation of one of the experienced over-clockers. I've never had any trouble; many of my Propeller projects use a 6.25 MHz crystal for 100 MHz projects.
• average joe Posts: 795

  2012-03-17 07:52 edited 2012-03-17 07:52

  Sorry if I sounded rude. Most of the theory taught in dc will help you understand how to figure bypass caps, etc. AC signals covers most of the rest of the theory. I'm COMPLETELY self - taught when it comes to electronics, so I'm no expert. I'll be the first to admit this. That being said.
  I design and build mixed signal boards which can be a HUGE pain. Grounding is a big issue, as well as decoupling. My latest board, while totally ugly, works perfectly.
  
  About tants starting fires. I was reluctant to play with tants when I first started out. Now all my designs use them. If you don't feel they fit your application, then feel free to disregard that. IMO, I would use a .1uf ceramic for each set of power pins, stashed under the prop. Put that crystal as friggin close to the chip as you can. Ground fill around the clock lines. Use nice fat power rails to the prop, and bypass these somewhere between the prop and the PSU with something larger. But that's me, and I'm no expert as I said.
• Sapieha Posts: 2,964

  2012-03-17 08:11 edited 2012-03-17 08:11

  Hi average joe.
  
  As You said --> Look marked TEXT --- It is BIG Pain --- BUT what most of people don't think on are that PROPELLER are mixed signal IC.And all Ic's that have PLL inbuilt.
  
  Every PLL have part called VCO that are in nature AC design. It is why that need good decoupling samt Voltage bust Capacitors to hold Voltage to this circuity very stable for good linear functioning else it will simply BURN theirs transistors as them starts work in opposite states in same time --> (simply said).
  
  More over is that Digital side of Propeller have very fluctuating CURRENT consumption And that give extra problems to constructing of PCB for it.
  
  

  average joe wrote: »

  Sorry if I sounded rude. Most of the theory taught in dc will help you understand how to figure bypass caps, etc. AC signals covers most of the rest of the theory. I'm COMPLETELY self - taught when it comes to electronics, so I'm no expert. I'll be the first to admit this. That being said.
  I design and build mixed signal boards which can be a HUGE pain. Grounding is a big issue, as well as decoupling. My latest board, while totally ugly, works perfectly.
  
  About tants starting fires. I was reluctant to play with tants when I first started out. Now all my designs use them. If you don't feel they fit your application, then feel free to disregard that. IMO, I would use a .1uf ceramic for each set of power pins, stashed under the prop. Put that crystal as friggin close to the chip as you can. Ground fill around the clock lines. Use nice fat power rails to the prop, and bypass these somewhere between the prop and the PSU with something larger. But that's me, and I'm no expert as I said.

  
  
  Ps. rwgast_logicdesign -- I can't read Yours attachment -- My FireFox Say Apache ERROR
• average joe Posts: 795

  2012-03-17 09:25 edited 2012-03-17 09:25

  @Sapieha, I never thought about the prop being a mixed signal ic, but you're totally right. This would push my opinion of building a prop board from moderate to expert. Especially if you plan on overclocking it. I've dealt with some really annoying mixed signal issues before. Audio signals are especially troublesome. So many designs scrapped because there's the faintest bit of noise in my guitar signal, until I turn the distortion,and the small noise becomes HUGE.
  
  As far as constructive criticism:
  I see 4 voltage regulators, connected to vin. no mention of what voltage so I'm guessing 3.3v?
  I would add at .1uf cap in parallel with the 10uf output cap. That is, connected to output and ground. Might not be necessary, but I do this on all Vregs.
  What is Vin? a wall wart? what voltage? how many amps?
  90% of the work on a mixed signal board is getting the layout right. Where you put the chips on the board, in relation to everything else. Where the ground planes go.
  
  As I said. I never meant to be rude, I just think others have this one wrapped up. Do you have some requirement not covered by existing boards?
• Sapieha Posts: 2,964

  2012-03-17 09:54 edited 2012-03-17 09:54

  Hi Joe.
  
  I can't talk on his design as I don't see it in my FireFox. Only an error from his server.
  If hi post BMP on forum I can give some info to it!
  
  Even if I have that I never think on it. It is Years of experience with electronic's.
  
  Don't worry of rude -- I always answer questions that need answers.
  
  "I would add at .1uf cap in parallel with the 10uf output cap."

  ---

  > Vreg on Out side always need both .1uF and one 10-47uF In some case even bigger ---> It is Curent draw from it that decide that.
  In addition even V-in side need some careful decoupling IF You drive it from Battery --> Most of them are very sensitive to AC transients produced by V-Regs.
  "Do you have some requirement not covered by existing boards?"

  ---

  > Is it My boards else all boards that are presented on Forum?
• frank freedman Posts: 1,983

  2012-03-17 11:12 edited 2012-03-17 11:12

  If you can even find a copy of a book titled "Well Tempered Digital Design" look through it. It is "old", but many things have not changed. I found it very useful in the past for some things, but for much more detailed and current is Tim Williams "Circuit Designer's Companion".
  
  FF
• Duane Degn Posts: 10,588

  2012-03-17 11:24 edited 2012-03-17 11:24

  Sapieha wrote: »

  I can't talk on his design as I don't see it in my FireFox.

  
  Here's his schematic converted to a jpg (it would nice if rwgast stopped posting bitmaps).
  

  

  

  

  reg[1].jpg

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  reg[1].jpg 40.4K
• rwgast_logicdesign Posts: 1,464

  2012-03-17 12:55 edited 2012-03-17 12:55

  @Average Joe, Hey man Im sorry for being such an a** in my reply, I had been up like 24 hours and some of the stuff you said is a huge peeve of mine, I could have been alot less rude man. Trust me if i could afford a class I would be back in school getting my Electrical or Computer Engineering degree, Im hoping my hobby will be able to get me in school at some point I learn fast and am reading a book called Electrical Engineering 101: Things your teacher never taught you. I also work started my electronics intrest with guitars and hi-end car stereos, I had a ground loop in a very nice guitar for years from following the companys schematics, it didnt get fixed until I became an electrician and took a DC Theory class .
  
  @frank, Thank you I will definitely check out the book!! Im always looking for any good reading related to my projects! Its hard to find electronics books that are written well and really teach you something, I have bought many books over the years that have gotten me nowhere such as, 100 pic projects for evil geniuses, awfull book just a bunch of source examples and editing errors, so any good books are welcome!
  
  
  @Sapieha and Duane, Im sorry for the .bmp files. They are basically just what express pcb exports, I didnt think they would be a problem. Here we go
  
  My Regulation fixes,
  
  http://dl.dropbox.com/u/27653605/regsGIF.gif
  
  This is two different regulator layouts the first one being the way i interpret all most all the schematics I read, just redrawn in a way that make sense to me. This is the top set of regulators. The bottom set is the way I believe that they should be wired, In my head the bottom one sends the electricity to each regulator, so I will have two identical power rails. For anyone who is confused these are both 3.3v regulators. The purpose is so the propeller dip can have its very own regulator to make OC that much more stable, the second is to power everything else.I chose the caps based on the data sheet for the regulators, apparently I need to add a bigger one in parallel to the outputs? Please guys let me know which if either of these designs are right. As far as power Im using an adjustable wall power supply (1.5v-12v) on the 6 or 9 volt setting, it is capable of 1300mA.
  
  Here is my whole PCB in gif format. The regulators are obviously not right.
  
  http://dl.dropbox.com/u/27653605/modGIF.gif
  
  Like I said I will be replacing the .1uf caps of the props VDD lines with 4.7uf caps. I will also be adding a 10uf in parallel with the two 4.7uf(like is said there .1uf now i havent made the change to 4.7 yet) caps on the VDD pins, I only need one 10uf for both VDD pins correct? Or do I need a 10uf cap in parallel with each 4.7uf cap?
  
  I would like to thank everyone who has looked at my stuff and is helping me out, im very grateful. I think my board
• frank freedman Posts: 1,983

  2012-03-17 14:30 edited 2012-03-17 14:30

  Free courses and materials:
  Allaboutcircuits.com is a decent tutorial site, actually closer to textbooks but with a forum for discusskons. Good site for average bear.
  Open courseware such as the MIT OCW site, but be ready for some math.
  
  In these days, there is little reason to spend money on learning unless some cert or degree requires proof of mastery. It is all out ther if you take the time to look and be creative with google.
  
  It would not hurt to find a good reference on elex drafting practices, I am sure the up and to the right grounds and diagonal lines will have a few of the old guard cringing at the site of them :-/
  
  FF
• average joe Posts: 795

  2012-03-18 04:14 edited 2012-03-18 04:14

  @logic, I completely understand what you are talking about. There are many wonderful resources out there on the web. If not for this, I would be screwed. The community here is very friendly and I didn't mean to sound hostile, although I must admit I did.
  
  Decoupling is not Dc theory, it's actually AC theory. The best way I can explain it is, that capacitors pass AC but block dc. Putting them between the supply pins allows the AC currents from gates transitioning and whatnot, to pass between the supply pins. The smaller caps pass higher frequencies, and the larger caps pass the lower frequencies. Applying two caps in parallel widens the "Q" of each cap. Don't forget that each wire on a board is effectively a resistor. So putting two caps in parallel, you actually make an RC circuit.
  
  As to the reason most designers use the regulators in series, I believe it's because it allows them to supply the board with higher voltage power supplies among other things. The 3.3 volt regulator must drop some of the voltage and by regulating it down to 5, the 3.3 must drop less voltage. This means the regulator will run cooler.
  
  Frank is right about your drafting. My schematics are less than perfect. But looking at your schematics was the reason I suggested something a bit simpler. Overclocking the prop is quite advanced IMO. You may be able to design a board that works, and will clock up-to 100M but there's a chance that it could have gremlins.
  
  I am still interested WHY you want to build this as there are a number of excellent boards out there. Reading through your posts, I couldn't find any information what you need that is not available. Do you have a form factor requirement? Some other specific reason? I know of several boards that OC to 96 quite easily. If I had the right crystal, I'd slap it in my propRPM and stiffen the supply caps a bit. Trying to squeeze the extra 4mhz sounds nice, but when you're talking about an 80mhz chip, the OC to 96 is big. Those extra 4 mhz are a small percentage improvement and unless you REALLY NEED them, I wouldn't waste my time.
  Honestly, I would pick up a board somewhere else, and get to prototyping. Re-designing the wheel sounds fun until you realize it was fine to begin with. If it's not broke, fix it till it is! Wait, that's my OLD motto.
• Dr_Acula Posts: 5,484

  2012-03-18 05:23 edited 2012-03-18 05:23

  Here is my whole PCB in gif format. The regulators are obviously not right.
  
  http://dl.dropbox.com/u/27653605/modGIF.gif

  
  Please don't take this the wrong way, but there are so many things wrong with that drawing and there is a 100% guarantee it will not work. See Jon's post #4.
  
  Start simple. Draw a line along the top of the drawing. Call this "3.3V". Draw another line along the bottom. Call this "0V".
  
  Now start with the regulator. Put it on the left hand side of the drawing. Vin is the input volts. Vout goes to that top line. Gnd to the bottom line.
  
  Have a look at some schematics of how a regulator works. The capacitors are between 3V and 0V. Not between Vout and the 3V rail, otherwise no volts can get through. See on the schematic below the symbol for the 0.1uF cap - it is like two plates that are not connected. This is like a real capacitor. Some of the original capacitors were like this. Take a glass jar - wrap the outside in aluminum foil, and put foil on the inside as well. That is a capacitor. No electrical connection between the two pieces of foil. But it can hold a charge, and that is what a capacitor does. Make the jar bigger, and it can hold a bigger charge. http://www.alaska.net/~natnkell/leyden.htm
  
  Draw up a schematic for a regulator, build it, and see if you can get a led to light. Do that before you add a propeller or any other chips.

  

  

  Schematic1.jpg

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  Schematic1.jpg 19.4K
• rwgast_logicdesign Posts: 1,464

  2012-03-18 13:02 edited 2012-03-18 13:02

  @frank thanks the allaboutcircuits.com is a very nice site, it complements the book im reading right now very well.
  
  @joe, like I said its all good, thanks for your input, maybe you could explain to me why you use tants instead of ceramics. Ive done tons of reading on decoupling so I could design the most stable board I possibly could. Everything I know says that ceramics have much lower ESR, there range is alot tighter -+10%, so in return they have a super good response speed needed in decoupling. All this without the safety issues. You aren't the only one who uses tants in there designs, I know clusso uses a 10uf tant in parallel with his .1uf's on the TriBlade and RamBlade. So i background Im wondering why tants???
  
  Anyways the reason for designing my own board is... there is only one board close to what Im looking for and its the CPUModule at mikronaughts, which i linked to a little earlier in this thread. I emailed him trying to find out if there were kits available since the site lists a kit with no price, still waiting to hear back though I plan to make this my main prop board. I want to design my own board because im interested in eventually designing my own computer. Im coming from a low level programming background mostly, and Im very interested in lench arning more about hardware design. Pretty much no utilitarian type of purpose for any of this, its all an academic lauch pad,
  
  @Acuala Thanks for the tips, I had originally planned to build a separate power supply but everything I have read said you need to keep the reg as close to the cap as possible if you want to be able to overclock. Like I said before the was schematics may look weird to people but there the way they are because Its what makes sense to me in my head when I look at wires and connections, and there partially like they are because Ive done quick fixes to get quick feedback. At this point im mainly trying to get a correct parts list, and planed on redesigning the schematics after thats done.
• Dr_Acula Posts: 5,484

  2012-03-18 15:12 edited 2012-03-18 15:12

  ok, regulation design distilled down to the simplest principles:
  1) Put a large value cap across the input of the regulator. 470uF to 2200uF electrolytic. Make the voltage rating higher than the highest volts you will ever put on the input. This smooths the input if you happen to have a wallwart where they didn't put a big cap inside the wall wart. For batteries, 470uF should be fine.
  2) Across the output of the regulator, look up the spec sheets for that regulator and do what they say.
  3) Next to every chip on the board, put a 0.1uF ceramic between that chip's supply pins. Think of this as a little local power supply for that chip.
  4) Follow the recipe for the prop. There are two power supply pins, one set at the top of the chip and one along the bottom. Put 0.1uF ceramics across each of these, right next to the chip. The way the layout of a DIP40 works, I find the 0.1uF caps go right next to the chip. The above the top one goes the xtal. and below the bottom one goes a tantalum.
  
  
  The other thing - you haven't fixed things on the schematic that go back to post #4 and I would be worried that some of the people who made suggestions on the first page of the thread have stopped answering. So with less people answering the feedback might get slower.
  
  Can you post a new schematic by any chance?
• Bill Henning Posts: 6,445

  2012-03-18 19:25 edited 2012-03-18 19:25

  rwgast_logicdesign wrote: »

  Anyways the reason for designing my own board is... there is only one board close to what Im looking for and its the CPUModule at mikronaughts, which i linked to a little earlier in this thread. I emailed him trying to find out if there were kits available since the site lists a kit with no price, still waiting to hear back though I plan to make this my main prop board.

  
  Hi - sorry about that. Sapieha kindy pointed me at this posting.
  
  I will check my spam folder sometimes the filter is over-aggressive; but to answer your question above, kits are available, I will find your email, or pm you, once I find the price in my nots (hopefully tomorrow!).
  
  Update:
  
  yep, it was in the spam folder. You are now white listed.