Maker Pro
Maker Pro

8-Pin Development Board

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
Looks pretty good even with a few specks of dust. Maybe I can buff those off with a green pad and spray some clear Krylon enamel over it. Back in the day, I used a technical pen with India ink to apply outlines and dry transfer letters to apply text. Sprayed on two or three coats of clear Krylon and let it dry in a dust-free room. I just watched a YouTube video where he used finger-nail polish remover (FNPR) to transfer laser printed legends. Cleaned the board with FNPR, laid the mirror-image printed paper on top of it, then wiped FNPR on the back side of the paper with a rag until the artwork showed through. Let is dry until paper was opaque again, then peeled off the paper. Some toner was left on the paper, but most of it transferred to the board. I don't think this works with water-soluble inkjet ink. Most FNPR is acetone-based.

I think I will go to Staples, or Best Buy, or maybe even MicroCenter, to see what is available in laser printers. Not ready to buy yet, just looking.

That assortment of caps and resistors you linked to appears ideal, and the price is reasonable with free shipping. I might order a few of those after I get to Florida.
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
I just watched a YouTube video where he used finger-nail polish remover (FNPR) to transfer laser printed
I have seen similar videos and have tried it myself. It works ok. The toner transfer method is more efficient and nearly foolproof with the right paper. So far I have had really good success with that yellow dextran coated paper. I would highly recommend that for a quick and easy way to do the transfer for prototyping.

Not ready to buy yet, just looking.
LOL, that's what she said :eek::D:p
Look at what followed me home ;) - I think someone once said that if your tools to project ratio is anything less than 10:1, you're doing it wrong :rolleyes:

That assortment of caps and resistors you linked to appears ideal, and the price is reasonable with free shipping.
I thought so too! I am not keen on having all those strips floating about, but I am sure a solution can be found cheaply.

after I get to Florida.
How's that going? When you get down here you interested in opening up a maker space? LOL
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
Here is ver. 2.0 - now, I won't have to worry about bad connections on the breadboard!! The integrated ICSP should make it a breeze to reprogram as well as having a working MCLR circuit.
The board has 16 thou traces, etched in Ferric Chloride (6 minutes) and tinned after failed soldermask was sanded off... The solder went no easier or harder for the tin coat, but its nice to know that the board won't oxidize any further.

Now to get to learning how this pic takes analog input!

20160601_204643_zpsevzcieqo.jpg

20160601_204733_zpsr7kndu2t.jpg
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
Nice job soldering the through-hole components, John. Now go scrub the flux off with 90% isopropyl alcohol using an "acid brush" with the bristles cut short to stiffen them up. Or use a stiff tooth brush.:)
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
Thank you! LOL, but I did!! Do I need to hit it again? I had to be careful as the silkscreen side is not fully cured. Didn't want to ruin that side with the solvent.
A copy is in an envelope for the mail carrier to bring to you ;-)
 
Last edited:

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
You can wait a few days until the component-side fully "cures", then hold the board vertically with the bottom edge over some paper towels or rags while you apply the alcohol. Let the excess flow down the board to be absorbed by the towels. Might want to fill a small plastic spray bottle with alcohol so you can direct the spray, but I usually just dip the brush in alcohol and scrub away, liberally dousing the circuit-side with alcohol to carry away the flux.

If you are careful, no alcohol will appear on the component side. If you do get some alcohol on the component side, just flood that side with alcohol but don't scrub it. Just let the alcohol roll off the board until just a thin film remains that quickly evaporates. This works best with lettering that is protected (crystal clear Krylon?) and fully "cured" and doesn't dissolve in alcohol of course. Here is another spray-on acrylic conformal coating.

Be sure to use as high a percentage of isopropyl alcohol as you can find. Usually this will be 90% but anhydrous industrial grade is even better, although it is normally sold in five-gallon containers. Once the container of alcohol is opened it will begin absorbing moisture from the air, so best to un-cap, pour some into a working container (a shot glass works well), and re-cap the original container. NEVER use ordinary rubbing alcohol: it contains too much water and does not evaporate quickly.

A properly de-fluxed board shows no trace of solder flux residue anywhere. Apply a conformal protective coating if desired, but I never bother with that. The real deal is pretty nasty to work with and dries to a hard rubbery consistency. Good, maybe even mandatory, for use in hot, highly humid, environments... like the jungles of Viet Nam for example.:D
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
I may clean it again or pitch it out the window....:mad:

I find the pickit 3 to be a bitchy little thing... It complains severely about its sensed voltage across the chip... It has to be within an 1/8 of a volt or it seems to throw errors....
I managed to get it to work on-board by removing all the jumpers. Thank God for jumpers!!! LOL - but again, not very convenient or conducive to experimentation which was the whole purpose of the board.
I understand that the nature of the programmer is not commercial or industrial, but if you are to use this as an ICSP, make it such that it has enough current to get the job done Microchip! The board is not heavily populated, four LED's total!!! When I try to program it with power delivered from the v. regulator it says :
"
Target voltage detected
Target Device ID (0x0) does not match expected Device ID (0xfc0).
"
When I program it with Pickit3 provided power
"
Connecting to MPLAB PICkit 3...

Currently loaded firmware on PICkit 3
Firmware Suite Version.....01.41.06
Firmware type..............Midrange

Programmer to target power is enabled - VDD = 4.750000 volts.
Unable to connect to the target device.
Failed to get Device ID
"
Only by removing all the jumpers and allowing the programmer to supply power did I get it to work.

Version 3.0 should have a switch to toggle all ICSP pins :rolleyes: Perhaps a dip switch could be used for that purpose? I will have to give it some thought.
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
FYI - the existing board (ver 2.0) has a mismatch between pins 6/7 of the pic chip. No big deal as the software can select which is analog and which is digital, but it would be frustratingly long to look for that....

Ver 3.0 - hopefully this would fix the ICSP issue by isolating it completely!

The only pins left on the 'rails' are pin1 Vdd, pin8 Vss and pin4 MCLR. The rest are broken by the spst dip switch. When the ICSP is in use, power will come in on pin2 of the ICSP jumper and flood the top rail, blocked by D3, will temporarily go down the 1k resistor that feeds C3, when that is full, it will then keep pin 4 of the pic high - which is what pin1 of ICSP does anyway. The question here is whether or not the programmer will be able to take this low when it needs to when cycling through its programming states. This I do not know..

Technically, the switch for GP1 disconnects the circuit, so I don't need to dip pin 6 out of the circuit, if the circuit layout is too difficult, this is an option to remember. GP0 (pin7) required two dip's to not only disconnect pin 7 from the circuit, but also to conserve power when the ICSP is in programming mode, otherwise power is bled across the pot to ground.

I think that this might be a decent solution to isolating the ICSP from the rest of the circuit for programming in place on the board. What are your thoughts?

edit: if it's sloppy, I apologize, I am not sure how to tidy this up any better since there are so many packages with multiple connections!!



ver3.0.png
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
Don't pitch it yet! Try removing the caps you have in parallel with the pull-up resistors for the two tactile switches. The PICKit 3 cannot drive pins 4 (Vpp), 6 (ICSPCLK) and pin 7 (ICSPDAT) if any of these pins has been "by-passed" or loaded (like with a potentiometer!). I have always used the PICKit 3 with power applied to the PIC from a regulated +5 V DC supply. It should work with the PICKit 3 providing PIC power from the USB cable connection, but I never do that. Remember, during reading and programming, those three pins have high-speed digital pulses on them and timing is critical. Don't slow things down by adding any additional circuitry to those three pins.

If you haven't done so yet, download the PICkit 3 Programmer/Debugger User's Guide. Pay particular attention to section 2.4.5 Circuits That Will Prevent the Debugger From Functioning. It is also a good idea to download and read the Multi-Tool Design Advisory.

I like the idea of using DIP switches (instead of jumpers) to isolate peripheral connections. Need to use a quality DIP switch designed for frequent changes in DIP switch settings.
 
Last edited:

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
Don't pitch it yet!
It's serviceable, but not fun for frequent changes - which was the purpose of the board, LOL... sigh

The PICKit 3 cannot drive pins 4 (Vpp), 6 (ICSPCLK) and pin 7 (ICSPDAT) if any of these pins has been "by-passed" or loaded (like with a potentiometer!).
Interesting - I was bypassing all pins, so there is potential here to use a smaller dip switch and just isolate those three pins. I will experiment with that later. edit - success, just removing those three jumpers allows the programmer to work properly - thanks Hop!!! Multiplexed pins keeps me spinning :-0

f you haven't done so yet, download the PICkit 3 Programmer/Debugger User's Guide. Pay particular attention to section 2.4.5 Circuits That Will Prevent the Debugger From Functioning. It is also a good idea to download and read the Multi-Tool Design Advisory.
Awesome, thank you - I will be reviewing those shortly!!! (I took a quick peek - was happily surprised that my addition of a schottky diode in ver 3.0 was what Microchip recommends also, LOL :D)

I like the idea of using DIP switches (instead of jumpers) to isolate peripheral connections.
Thanks. I would still keep the jumpers so that you can breadboard circuits, bypassing the dev. board.
 
Last edited:

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
Upon further review of the multi tool design advisory, it looks like the dip is not necessary! Apparently, if you setup the circuit properly, you can direct the flow using nothing more than a resistor or diode :)
Electricity follows the past of least resistance, so during programming, if it branches to the resistor, less flow will go that way. Sizing varies quite a bit from 1-10k and they state this is based on ensuring the logic levels are met. I am going to redo my ver. 2.0 schematic and see if there are places where I can insert a schottky and two resistors on the existing board.

edit: not sure of how to calculate what would be acceptable for the resistor's values so I will start at 1k. Here is what the schematic looks like with the adjustments - off to drill!

pic dev ver 2.1 schematic.png
 
Last edited:

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
Multiplexed pins keeps me spinnin
Yeah, somewhere in another thread I noted that Microchip engineers would multiplex power and ground on one pin if they could figure out a way to do it.

Electricity follows the past of least resistance
No it does not. Electricity knows diddly about resistance. We may observe that in a parallel circuit more current flows in the lesser resistance than in the greater resistance, but the electricity just does its thing without any conscious "knowledge" of which path it "should" follow. If the resistors obey Ohm's law and Kirchoff's voltage and current laws, we can calculate what the currents in, and the voltages across, the resistors will be. These calculated results as well as the actual measurements we make do not obey "electricity foilows the path of least resistance." Electricity doesn't "follow" anything. It just is. Hopelessly pedantic @Ratch could explain this much better than I can. I hate anthropomorphizing in an attempt to dumb-down complex things like electricity.

I am going to redo my ver. 2.0 schematic and see if there are places where I can insert a schottky and two resistors on the existing board.
I fail to understand the purpose of the Schottky diode shown in the Microchip note, unless Vpp is driven greater than +5 VDC by the PICkit 3 pod. Edit: Ummm. It DOES drive it more positive than Vdd during programming, as much as 14 V! If that happens, the Schottky diode should disconnect that monstrous 0.1 μF cap from the /MCLR input. It does nothing to help drive /MCLR low when the PICkit 3 pod attempts to drive it low. I would leave the cap and the diode out of the circuit and just use a 10 kΩ pull-up to Vdd tied to the /MCLR line. Maybe some research on the Microchip Forum can shed some light on this.

FYI - the existing board (ver 2.0) has a mismatch between pins 6/7 of the pic chip.
What does this mean? What is mismatched? Did you correct it for Ver. 3.0?
 
Last edited:

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
Yeah, somewhere in another thread I noted that Microchip engineers would multiplex power and ground on one pin if they could figure out a way to do it.
Don't get me wrong, I think it's brilliant - but for a beginner its a lot to take in. One step at a time.

I hate anthropomorphizing in an attempt to dumb-down complex things like electricity.
Feel free, I am still getting on with the math of electricity o_O:oops::mad:. I think Ratch stays far from me, my last KVL/KCL homework assignment a few years back had him in pain. Poor steve had to take narcotics to deal with it!

I fail to understand the purpose of the Schottky diode shown in the Microchip note
It stops the power from "leaking out" into the main circuit and keeps it running directly from ICSP to the chip. That way the programmer doesn't throw - voltage errors as too much current is consumed and v drops.

What does this mean? What is mismatched? Did you correct it for Ver. 3.0?
I goofed during layout and put the anticipated components for pin 7 on pin 6 of the pic and vice versa. The board is incorrectly labelled GP1 for the tactile switch when really its GP0 and the pot is really on GP1 not GP0 as labelled.

The circuit will still work, just have to sharpie in correct locations to make it easier when programming to call on the correct hardware.

I scrapped ver. 3.0 since 2.1 ;) works
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
So I can use the board I receive in the mail (eventually) without track modifications? Yee Haw! I've got a fine-point Sharpie around here somewhere...

Are we ready for some A/D programming? Need any help with that?:p
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
So I can use the board I receive in the mail (eventually) without track modifications?
LOL - I am confident in our postal quality! This time it's a simple envelope so I should expect it to be there by saturday. As for track mods - the only holes you will need to drill are the ones I showed in post 71 to accommodate the schottky and the two resistors.

Are we ready for some A/D programming? Need any help with that?:p
OH YEAH!! LOL, on both accounts. Ready to move forward and ready for the challenge :D and now that I have this nifty board to play with that won't give me faulty ground connections!!! I am so ready :)
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
I was watching this the other day, this is where I got my notion of electricity following the path of least resistance...
Code:
http://www.youtube.com/watch?v=OGa_b26eK2c&t=35m14s
He seem's to know what he is talking about, was an engineer at NASA, etc. Let me know what you think, I was considering ordering his dvd :confused::D
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
I think Ratch stays far from me, my last KVL/KCL homework assignment a few years back had him in pain.
I read the thread but saw no sign of Ratch. Steve and Laplace were mostly involved. Did you finish that course?

the only holes you will need to drill are the ones I showed in post 71 to accommodate the schottky and the two resistors.
I think I will leave those off of my board and depend on the jumpers for "isolation" instead when I program the PIC. What kind of Schottky diode did you happen to have on hand to use? All of my Schottky diodes are big Cree SiC diodes made to handle amperes of current and high reverse voltages... not really suitable here. The isolation resistors are a good idea if they don't interfere with the external circuitry. I may put those in because I can always replace them with short jumper wires later if need be.

I stopped by Radio Shack yesterday while I was waiting for my glipizide prescription to be filled at Walgreens. To my surprise, they are again catering to the hobbyist. Lots of discrete components still available in neatly labeled drawers along with "maker" kits on display in plastic baggies. They re-stocked the Seedstudios stock that I pretty much cleaned them out of last year when I was messin' around with Arduino Uno modules. This happened while RS was in the processing of closing a bunch of outlets in the Dayton area. I think there are only three stores left, but one of them is well-stocked and not far from where I live. Of course they still have walls full of remote control toys, Sprint cell phones, DIY telephone accessories, and a huge selection of batteries and chargers for same. But there are two rows now dedicated to hobby electronics, albeit all their "stuff" is way overpriced. A PINT of ferric chloride is about $15 IIRC! Still, if you know what you want and can find it online at their website, it's a lot easier and quicker to purchase from a bricks-and-mortar RS store than to wait for mail order.

I am confident in our postal quality! This time it's a simple envelope so I should expect it to be there by saturday.
When I renewed my ARRL membership this year, I had to pay extra to get QEX delivered by first-class mail because the six issues I received last year were mangled by the USPS. QST arrives in good condition, but it has more bulk and is printed on heavy, high-quality, glossy paper. I guess we'll see what they can do with a circuit board in an envelope.:rolleyes:
 

chopnhack

Apr 28, 2014
1,576
Joined
Apr 28, 2014
Messages
1,576
I read the thread but saw no sign of Ratch. Steve and Laplace were mostly involved. Did you finish that course?
Wow. You are correct, my apologies - it was Laplace that I was giving headaches to! No, I made it through the first week well enough, 90+ score, but the second week wiped me out. I was not able to keep up due to math.

What kind of Schottky diode did you happen to have on hand to use?
1N5819, also have the 5822 but its huge in comparison. The '19 was small enough, but I stuck in vertical between the 4 pin jumper and the 2 pin jumper by R2.

That is good news on radio shack, you did get my link about the ferric chloride, right?

we'll see what they can do with a circuit board in an envelope.:rolleyes:
Let's hope it arrives in good condition! When I used to mail stuff to ny or nj from down here it would only take 3 days so I am hoping yours should arrive by saturday. Let me know!
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,878
Joined
Jun 21, 2012
Messages
4,878
I was considering ordering his dvd
I wasn't impressed with his delivery. Of course there was no math involved in this introductory video since it appeared he was trying to lure in a totally clueless audience. But to talk about short circuits in the manner he did was totally wrong. He implied that the wire somehow "sucked in" all the available current leaving nothing for the fan because electricity "always takes the path of least resistance." This just isn't so.

Sure, in a practical instance, the voltage source will have a finite source impedance that is large compared to the resistance of a piece of wire, so the voltage across the fan and the short-circuiting wire will me much smaller than the voltage across the fan was before the short piece of wire was connected. But unless it is a superconducting wire with zero resistance, there will be some voltage across the short circuit and some voltage will appear at the fan. The electricity did NOT take the path of least resistance, although most of the current from the source did... faithfully obeying Ohm's Law and KCL and KVL.

So, yes, buy the DVD if you like his presentation, but I would view the course on-line first. Just because a person is knowledgeable in a subject doesn't mean they are a great teacher. And even the best teachers sometimes make ill-advised remarks. To fill someone's head with the notion that electricity "knows" how to find the path of least resistance and "must" follow it is just wrong. It serves no useful purpose that I can see, and could possibly interfere with understanding of circuit analysis later on.
 
Top