Learning electronics: Release the Magic Blue Smoke

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Cyril Sneer: Aug 8, 2004; Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

turbo sex bat 4000 posted:

Because a cheap crimping tool is called a pair of needle-nose pliers.

It is kind of ridiculous but if you ever have to do more than a hundred crimp connections in a day it makes sense. You have to be able to rely on the connections you make.

That doesn't address my question. I'm well aware of the need for crimp tools. My point is that I don't see why they can't be mass produced and sold for much cheaper.

# ? Jun 17, 2009 14:49

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# ? May 21, 2024 16:09

SnoPuppy: Jun 15, 2005

Cyril Sneer posted:

That doesn't address my question. I'm well aware of the need for crimp tools. My point is that I don't see why they can't be mass produced and sold for much cheaper.

Probably because the hobbyist market isn't their target? I'm sure most sales go to companies, who don't really care that much about footing the bill for a $500 crimp tool.

It's the same reason why a flight on Monday morning is expensive - that's when business travelers like to fly, and airlines know that their companies will pay.

# ? Jun 17, 2009 14:54

ANIME AKBAR: Jan 25, 2007; afu~

BattleMaster posted:

Oh, one thing I forgot to add is that all PICs have a Watchdog timer that can be used to wake it from sleep, but I never use it so it slipped my mind. The one on the baseline devices can only be set to overflow in a maximum of 2 seconds, but the one on midrange devices like the two I listed can be set to overflow in several minutes.

TIMER1 with a 32KHz crystal uses less power and is more precise, though.

Yeah, I was aware of the watchdog wakeup. Thing is, it's not really a wakeup, but rather a full reset, meaning it doesn't resume execution at the last instruction and it (probably) clears all nonvolatile memory. This might be fine for some applications; possibly mine. I'm not really sure yet.

# ? Jun 17, 2009 15:19

ANIME AKBAR: Jan 25, 2007; afu~

For a design I'm intending to sell, I want to include a simple buzzer for status indication. Needs to be decently loud (at least 85db), simple/low cost to drive, and small in size. Right now I'm using a magnetic buzzer, which is okay, but the thing with magnetic and piezo elements is that they have pretty narrow resonance, and I'd like to be able to produce a better variety of tones at a consistent power level (an octave, if possible). Actual speakers are a little too expensive (like around $5) for what I want. Anyone know of a device type that would be suitable?

ANIME AKBAR fucked around with this message at 15:39 on Jun 17, 2009

# ? Jun 17, 2009 15:33

thepartypooper: Jul 4, 2002

I'm running into a problem using the SPI interface on a PIC32. Looking through the user guide and the peripheral library guide, it doesn't look like it supports the configuration I need.

I need to set it up as the master, and hold the slave select line low for the duration of the write (like the timing diagram here). What I'm finding is that it has 2 modes for master operation: normal, which doesn't use the slave-select line at all, and framed, which pulses the line at the start and end of the write (pictured below).

I know I could just bit-bang it, or use another IO for the SS (which raises other issues as far as synchronizing it with the TX frame), but I figured maybe I'm overlooking something. Anyone have any experience using SPI with this part?

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# ? Jun 19, 2009 08:33

Zuph: Jul 24, 2003; Zupht0r 6000 Turbo Type-R

thepartypooper posted:

I know I could just bit-bang it, or use another IO for the SS (which raises other issues as far as synchronizing it with the TX frame), but I figured maybe I'm overlooking something. Anyone have any experience using SPI with this part?

I'm not experienced with the PICs at all, but most SPI devices I've encountered aren't really sensitive to timing delays between the SS and other lines, so you could probably use another IO for SS without any issues.

# ? Jun 19, 2009 11:57

BattleMaster: Aug 14, 2000

You're definitely supposed to use GPIO for the slave selects. I've never heard of SPI devices being particularly sensitive to the timing of the SS signal.

# ? Jun 19, 2009 21:55

thepartypooper: Jul 4, 2002

BattleMaster & Zuph posted:

use another io

I've actually tried this like so:

code:

PORTClearBits(IOPort_A, BIT_0);
SPI1Write(0xaa);
PORTSetBits(IOPort_A, BIT_0);

but I end up with this:

code:


SS:   -----________------
Data: _________-_-_-_-___

At least with the current peripheral clock that I'm running, the SPI is still writing when the GPIO pin goes high. I know that it's probably not that sensitive, but I don't expect it to be as forgiving as to have the SS signal offset by half the TX frame.

FYI, this is what I'm trying to program: AD9833

From looking at the PIC library guide, there doesn't seem to be an easy way of testing if the SPI is done transmitting in order to easily use an IO pin in this way.

# ? Jun 19, 2009 23:08

BattleMaster: Aug 14, 2000

I don't know how that function works, but you need to wait until the SPI module is finished before setting the I/O bit high again. It looks like all the function does is load the output register and tell the module to transmit, without waiting for completion. ~~There is likely a function that you can use to find out if the module is done transmitting or not that you can use with a while loop to wait until it's done.~~ Edit: Oh, there's no function for waiting? Take a look at the data sheet and figure out what bit in what register indicates that SPI transmission is complete and just check that in a while loop or something.

I don't know any specifics about the libraries you're using, though. For basic things like SPI I just roll my own code instead of use the included libraries for it. I mean why call a function when all you need to do is load a register and set a bit?

BattleMaster fucked around with this message at 23:30 on Jun 19, 2009

# ? Jun 19, 2009 23:26

thepartypooper: Jul 4, 2002

I think that's what I'll have to do. I had seen that flag on the datasheet, but it doesn't seem to be exposed in the peripheral library. It seems like a strange omission to me.

thepartypooper fucked around with this message at 23:33 on Jun 19, 2009

# ? Jun 19, 2009 23:31

BattleMaster: Aug 14, 2000

thepartypooper posted:

I think that's what I'll have to do. I had seen that flag on the datasheet, but it doesn't seem to be exposed in the peripheral library. It seems like a strange omission to me.

I've honestly never used PIC32s, but the lower-end pics like the PIC18 series each have a header file that allows you to access registers and bits in them as if they were variables. For example, for a PIC18F4550 I need to include p18f4550.h and to loop until an SPI transmission is complete I can do something like

while(!SSPSTATbits.BF)

I bet you can do something similar with PIC32s. It would be pretty messed up if you could only use a premade set of libraries to interact with the I/O on the thing.

# ? Jun 19, 2009 23:41

Mill Town: Apr 17, 2006

BattleMaster posted:

I don't know how that function works, but you need to wait until the SPI module is finished before setting the I/O bit high again. It looks like all the function does is load the output register and tell the module to transmit, without waiting for completion. ~~There is likely a function that you can use to find out if the module is done transmitting or not that you can use with a while loop to wait until it's done.~~ Edit: Oh, there's no function for waiting? Take a look at the data sheet and figure out what bit in what register indicates that SPI transmission is complete and just check that in a while loop or something.

I don't know any specifics about the libraries you're using, though. For basic things like SPI I just roll my own code instead of use the included libraries for it. I mean why call a function when all you need to do is load a register and set a bit?

Yeah, looking at the datasheet, I think just waiting for SPIBUSY to clear is the best thing to do.

# ? Jun 19, 2009 23:47

thepartypooper: Jul 4, 2002

BattleMaster posted:

I've honestly never used PIC32s, but the lower-end pics like the PIC18 series each have a header file that allows you to access registers and bits in them as if they were variables. For example, for a PIC18F4550 I need to include p18f4550.h and to loop until an SPI transmission is complete I can do something like

while(!SSPSTATbits.BF)

I bet you can do something similar with PIC32s. It would be pretty messed up if you could only use a premade set of libraries to interact with the I/O on the thing.

Cool, I'll look into that. Thanks!

# ? Jun 20, 2009 00:18

Cyril Sneer: Aug 8, 2004; Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

SnoPuppy posted:

Probably because the hobbyist market isn't their target? I'm sure most sales go to companies, who don't really care that much about footing the bill for a $500 crimp tool.

It's the same reason why a flight on Monday morning is expensive - that's when business travelers like to fly, and airlines know that their companies will pay.

The hobbiest market doesn't have to be there target. It isn't that companies don't care about the cost, its that they have no other choice. If I could sell the same crimp tool for $100, guess who would get the (and every) sale.

Monday flights are expensive because the demand is high.

# ? Jun 20, 2009 15:43

Mah_Freend_Amee: Mar 7, 2007; GOOD DOG.
BEST FRIEND.; Grimey Drawer

I was hoping to get some input on a 50 - 80 dollar soldering station to replace the junk irons I have been using for almost entirely non-smd work.

I have been looking at these and don't mind spending the money for the Weller WES51 if it is worth it, but I am not sure:

http://www.amazon.com/dp/B000I30QBW/ref=asc_df_B000I30QBW829189?smid=AKJ57Q9VZBBO8&tag=dealt11104-20&linkCode=asn

http://www.amazon.com/gp/product/B0...&pf_rd_i=507846

http://www.amazon.com/gp/product/B0...&pf_rd_i=507846

# ? Jun 20, 2009 23:13

thepartypooper: Jul 4, 2002

I have this station: Hakko 936

When I bought it, I'd also been looking at the Weller WES51, but most of the info I could dig up pointed to this being a better station.

I've been very happy with it. It heats up fast, maintains temperature very well and there's a good variety of tips available. I got mine on ebay, but Amazon seems to have it cheaper right now.

Edit: If you order one, check to see which specific model number it is. There's 3 different ones (Hakko USA) with different irons. I've got the medium one, and it comes with a wedge tip that's pretty well suited to general purpose soldering, though not necessarily for really fine pitch SMT components. Plus the nice thing in my case is that the local electronics shop stocks tips for it.

thepartypooper fucked around with this message at 23:46 on Jun 20, 2009

# ? Jun 20, 2009 23:25

SpartanIvy: May 18, 2007; Hair Elf

I've got what I think is a quick question but i cant figure out how to properly ask google for an answer.

So I've got a automatic tire pump that is powered through a cars cigarette lighter, and it needs 12vdc and at least 10a. I need to figure out how to provide that kind of power with D cells or some other form of power that is lighter or at least cheaper than a car battery.

Again I know there has to be a way to do this but I can't figure out what to properly google to get my answer. Any help is appreciated!

# ? Jun 21, 2009 06:12

async1ronous: May 23, 2003; I flopped the nuts straight

Mah_Freend_Amee posted:

I was hoping to get some input on a 50 - 80 dollar soldering station to replace the junk irons I have been using for almost entirely non-smd work.

I have been looking at these and don't mind spending the money for the Weller WES51 if it is worth it, but I am not sure:

I have had a lot of luck with the inexpensive stations from https://www.circuitspecialists.com I happen to live down the street from them, but ordered one shipped to Texas as a Christmas present for my brother-in-law. He likes it as well.

# ? Jun 22, 2009 23:17

catbread.jpg: Feb 22, 2007

SpartanIV posted:

I've got what I think is a quick question but i cant figure out how to properly ask google for an answer.

So I've got a automatic tire pump that is powered through a cars cigarette lighter, and it needs 12vdc and at least 10a. I need to figure out how to provide that kind of power with D cells or some other form of power that is lighter or at least cheaper than a car battery.

Again I know there has to be a way to do this but I can't figure out what to properly google to get my answer. Any help is appreciated!

Your best bet is probably a smaller 12V sealed lead acid battery.

A mess of D cells big enough to provide that would be huge. And a mess.

# ? Jun 22, 2009 23:43

Zuph: Jul 24, 2003; Zupht0r 6000 Turbo Type-R

async1ronous posted:

I have had a lot of luck with the inexpensive stations from https://www.circuitspecialists.com I happen to live down the street from them, but ordered one shipped to Texas as a Christmas present for my brother-in-law. He likes it as well.

I bought a station from circuit specialists the same time a buddy bought the similar Hakko unit. There is no discernible difference between the two by any metric which matters. We aren't exactly soldering all day long, so I can't speak of long term durability, but I'm more than happy with my $35 saved.

# ? Jun 23, 2009 12:05

Keebler: Aug 21, 2000

Alright, I think I may have made a rookie mistake here...

I have an ATMega8535-16PU that I'm setting up to use serial communication with. I stuck it in my programmer last night and set the fuses to use an external crystal:

avrdude -p atmega8535 -P lpt1 -c dapa -u -U lfuse:w:0xef:m

That command went through without any issue. Now however I cannot communicate with the chip at all to program it, I can't change the fuses either. I'm using a simple parallel port programmer. Did I do something wrong or now that the fuses are set does my programmer need to have an external crystal to program the chip? I know the tool chain still works because I can put a second chip into the programmer and program it without issue (without blowing any of the fuses though).

# ? Jun 23, 2009 13:11

Zuph: Jul 24, 2003; Zupht0r 6000 Turbo Type-R

Keebler posted:

Alright, I think I may have made a rookie mistake here...

I have an ATMega8535-16PU that I'm setting up to use serial communication with. I stuck it in my programmer last night and set the fuses to use an external crystal:

avrdude -p atmega8535 -P lpt1 -c dapa -u -U lfuse:w:0xef:m

That command went through without any issue. Now however I cannot communicate with the chip at all to program it, I can't change the fuses either. I'm using a simple parallel port programmer. Did I do something wrong or now that the fuses are set does my programmer need to have an external crystal to program the chip? I know the tool chain still works because I can put a second chip into the programmer and program it without issue (without blowing any of the fuses though).

Yeah, you'll need to hook the chip up to an external crystal to reprogram it. That, or use a high-voltage programmer to reset the fuses.

# ? Jun 23, 2009 13:49

Keebler: Aug 21, 2000

That makes sense. I think I have a spare crystal or two I can dig out and clip on just to get it working. Thanks!

# ? Jun 23, 2009 14:00

scuz: Aug 29, 2003; You can't be angry ALL the time!; Fun Shoe

For those that cared when I asked, I would up getting a Weller WES51 and it sorts rules compared to my old econoiron. However something else has reared its ugly head...

My hands shake. Not so violently that I'm knocking things around, but enough that I'm prevented from soldering as precisely as I'd like to be. Do any of you guys/gals have to deal with this? Any advice? This is one of those things that may keep me from doing hands-on electronics down the line and I'd like to nip it in the bud if I could.

# ? Jun 24, 2009 19:13

Scarboy: Jan 31, 2001; Good Luck!

Does anyone know if there is a way to do what an analog switch (4066) does on a MCU or an FPGA (excessive!)? I have a circuit that uses 8 of these chips but they take up a lot of board space and end up costing more than a MCU would cost. I would obviously need a lot of pins on the chip to have equal functionality, but I have some ideas for things I can do to simplify the design if I can somehow do this on an MCU.

# ? Jun 24, 2009 19:33

Hillridge: Aug 3, 2004; WWheeeeeee!

scuz posted:

For those that cared when I asked, I would up getting a Weller WES51 and it sorts rules compared to my old econoiron. However something else has reared its ugly head...

My hands shake. Not so violently that I'm knocking things around, but enough that I'm prevented from soldering as precisely as I'd like to be. Do any of you guys/gals have to deal with this? Any advice? This is one of those things that may keep me from doing hands-on electronics down the line and I'd like to nip it in the bud if I could.

Try to relax. You're probably trying too hard to keep your hand still.

It may also help to find a way so that you can rest your hand/wrist on something and just guide the iron with your fingers. Not having a death grip on the iron is key. I've also found that I do better when I'm not loaded up on coffee.

# ? Jun 24, 2009 20:25

Zaxxon: Feb 14, 2004; Wir Tanzen Mekanik

Scarboy posted:

Does anyone know if there is a way to do what an analog switch (4066) does on a MCU or an FPGA (excessive!)? I have a circuit that uses 8 of these chips but they take up a lot of board space and end up costing more than a MCU would cost. I would obviously need a lot of pins on the chip to have equal functionality, but I have some ideas for things I can do to simplify the design if I can somehow do this on an MCU.

what exactly are you doing with the 4066?

for the most part this is impossible, in some cases it's possible.

Zaxxon fucked around with this message at 02:50 on Jun 25, 2009

# ? Jun 25, 2009 02:44

catbread.jpg: Feb 22, 2007

scuz posted:

For those that cared when I asked, I would up getting a Weller WES51 and it sorts rules compared to my old econoiron. However something else has reared its ugly head...

My hands shake. Not so violently that I'm knocking things around, but enough that I'm prevented from soldering as precisely as I'd like to be. Do any of you guys/gals have to deal with this? Any advice? This is one of those things that may keep me from doing hands-on electronics down the line and I'd like to nip it in the bud if I could.

If metal gear solid has taught me anything, try diazepam, or smoking.

# ? Jun 25, 2009 12:33

Cyril Sneer: Aug 8, 2004; Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

Does anyone here know EagleCAD really well?

All I want to do is flip/mirror a board. The built-in mirror function mirrors about the top and bottom sides - that is not what I want. I simply want to mirror the board about the Y-axis (ie, flip the left and right)

I have been completely unable to locate any such function to perform this, which is leaving me frustrated as its such a seemingly simple task.

# ? Jun 25, 2009 14:40

Plexiwatt: Sep 6, 2002; by exmarx

scuz posted:

My hands shake. Not so violently that I'm knocking things around, but enough that I'm prevented from soldering as precisely as I'd like to be. Do any of you guys/gals have to deal with this? Any advice? This is one of those things that may keep me from doing hands-on electronics down the line and I'd like to nip it in the bud if I could.

Sounds really lame but I've been known to wear wrist-weights before, the kind used for exercise. They decrease tremors the same way a cheap steadycam does--by increasing the mass of your arms such that little tremors are damped out. Of course you get tired faster, but for just a few connections it works. Especially if you're soldering while hung over, which I know absolutely nothing about.

# ? Jun 25, 2009 16:12

ANIME AKBAR: Jan 25, 2007; afu~

Cyril Sneer posted:

Does anyone here know EagleCAD really well?

All I want to do is flip/mirror a board. The built-in mirror function mirrors about the top and bottom sides - that is not what I want. I simply want to mirror the board about the Y-axis (ie, flip the left and right)

I have been completely unable to locate any such function to perform this, which is leaving me frustrated as its such a seemingly simple task.

it's not quite as simple as it seems. Mirroring each part (while keeping them on the same side of the board) would result in footprints that don't match up with the original; essentially making them entirely new parts.

Keep in mind that for most designs, doing what you're describing would make the board completely useless, since any device whose footprint isn't symmetrical about the flipped axis would not work on the flipped layout. Are you sure this doesn't apply to your design?

# ? Jun 25, 2009 19:02

Zaxxon: Feb 14, 2004; Wir Tanzen Mekanik

any of you guys ever messed with wire wrapping? A lot of projects I've been doing lately are just a microcontroller and a few other chips. WireWrap seems pretty cool for putting stuff like that together.

# ? Jun 25, 2009 21:57

Cyril Sneer: Aug 8, 2004; Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

ANIME AKBAR posted:

it's not quite as simple as it seems. Mirroring each part (while keeping them on the same side of the board) would result in footprints that don't match up with the original; essentially making them entirely new parts.

Keep in mind that for most designs, doing what you're describing would make the board completely useless, since any device whose footprint isn't symmetrical about the flipped axis would not work on the flipped layout. Are you sure this doesn't apply to your design?

I don't quite follow. If I take a graphical image of the board and mirror it in a grahpics program, it looks just how I want it to look.

# ? Jun 26, 2009 13:15

Hillridge: Aug 3, 2004; WWheeeeeee!

What's on the board?

He's saying that if you mirror the board, you will also mirror any footprints. For parts like ICs, this will mess up all the connections. The numbers below are the pins on an 8 pin IC, the dotted line is what they mirror over:

code:

You can't mirror the physical part, so when you solder it to the mirrored board, all the connections will be wrong.

There are a few cases of simple boards where this may not be true though, which is why I wonder what your board looks like.

# ? Jun 26, 2009 13:54

ANIME AKBAR: Jan 25, 2007; afu~

I recently read an article in EDN about energy scavengers, which are essentially power conversion devices capable of harvesting extremely low level signals from various transducers, like solar cells, piezo elements, and temperature gradients. These things are pretty amazing. One of the companies that makes these things, Advanced Linear Devices, has some products claiming to run off 0.4V, and they say they're aiming at devices that can run off 100mV and start up at 400mV. Of course this is essentially impossible with ordinary components (transistors won't even operate). But I've looked at their website and they have special processes which result in FETs with incredibly low operating characteristics, so that must be the secret.

Here's the EDN article:
http://electronicdesign.com/Articles/ArticleID/20931/20931.html

# ? Jun 26, 2009 15:54

SnoPuppy: Jun 15, 2005

ANIME AKBAR posted:

it's not quite as simple as it seems. Mirroring each part (while keeping them on the same side of the board) would result in footprints that don't match up with the original; essentially making them entirely new parts.

Keep in mind that for most designs, doing what you're describing would make the board completely useless, since any device whose footprint isn't symmetrical about the flipped axis would not work on the flipped layout. Are you sure this doesn't apply to your design?

If he's just using it to push stuff to the back side, it should work

# ? Jun 26, 2009 16:09

Scarboy: Jan 31, 2001; Good Luck!

SnoPuppy posted:

If he's just using it to push stuff to the back side, it should work

I've never tried, but shouldn't Eagle do this automatically if you select the back side solder mask? I know if you select the back side silk screen it will reverse the text for you.

# ? Jun 26, 2009 17:35

Snaily: Mar 5, 2006; Sluggish. Wee!

Scarboy posted:

I've never tried, but shouldn't Eagle do this automatically if you select the back side solder mask? I know if you select the back side silk screen it will reverse the text for you.

I'm fairly sure this is exactly what the mirror command in Eagle CAD does.

# ? Jun 26, 2009 21:39

micron: Nov 15, 2005

I need a bit of helping finding something or even such a thing exists. I'm looking for a Hall effect pickup sensor. Not a standard Hall but one that gives an analog output linear to the magnets distance to the sensor. Everything I find is just an on\off magnetic sensor.

# ? Jun 26, 2009 22:02

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# ? May 21, 2024 16:09

Chalupa Joe: Mar 4, 2007

Snaily posted:

I'm fairly sure this is exactly what the mirror command in Eagle CAD does.

It is:

In the schematic editor MIRROR flips the symbol over so that your nets can be laid out clearly without messes of wire going everywhere.

In board layout MIRROR moves a component (or group of components) from one side of the board to the other.

Of course... in board layout view, you're looking down on the top (component side for through hole) of the board, anything on the bottom layer appears to be "backwards" but when the actual PCB is made, it ends up around the right way.

# ? Jun 26, 2009 22:16

The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Learning electronics: Release the Magic Blue Smoke

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