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I'm trying to get a Newhaven Display NHD‐0420CW‐AB3 4x20 OLED display running over I2C and I must be missing something stupid because I can't get the screen to turn on. I have it wired up for a 5V I2C connection as shown on page 4 of the PDF, and I can see on the oscilloscope that the device is sending an ACK bit when it should so the device must be listening and I should have the bus address right. The I2C line chatter looks something like this: Start bit Address + Write [ACK] Byte telling it I'm about to send it a command (0x80) [ACK] Command to turn everything on (0x0F) [ACK] Stop bit At that point I'd expect to see the backlight kick on or something, but nothing happens. I also tried writing some characters to the screen and then side-lighting it with a flashlight without any luck. Any ideas as to what to check or try next?
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Feb 25, 2015 02:10
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Just a sanity check but you have VDD as a no connect not GND right?
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Feb 25, 2015 02:20
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ante posted:I learned in school that some fluxes will cause corrosion over time, but I'm not sure how true that is, or what kind of fluxes or anything. Correct. The entire purpose of flux is to dissolve any oxidized metal that's formed on the legs/surfaces of the components you're soldering together, allowing solder to fully wet the component and fill the joint. For most flux chemistries, the active part is a mild acid, which converts the oxide to salt + water. Two bad things can happen if you don't wash off the residue: * The salt byproduct is ionic, so it can trigger all sorts of nasty interactions with the metal over time, especially if you're in a humid climate. The most irritating one is growth of crystal dendrites, where the metal starts growing new crystals of itself, which can gently caress you up if two crystals touch each other and you now have a electric connection. * If there's any leftover acid, the reaction can continue well after after soldering is complete. This not only directly eats the metal away, but produces more salt, leading to the above. When you see fluxes described as organic/inorganic, active/mildly active/low activity, etc., it's describing how powerful that acid is, and to a lesser extent, how active it will be at room temperature.
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Feb 25, 2015 03:02
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Popete posted:Just a sanity check but you have VDD as a no connect not GND right? Yep, the pins go like 1) VSS - GND 2) VDD - No connect 3) REGVDD - +5V 4) SA0 - GND 5) GND 6) GND 7) SCL 8/9) SDA 10-15) GND 16) *RST from microcontroller, 10k to GND pull-down, controller pulls it up 100ms after powerup 17) BS0 - GND 18) BS1 - +5V 19) BS2 - GND 20) GND e: added the other pins in case someone spots something wrong PDP-1 fucked around with this message at 03:46 on Feb 25, 2015 |
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Feb 25, 2015 03:29
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ante posted:I learned in school that some fluxes will cause corrosion over time, but I'm not sure how true that is, or what kind of fluxes or anything. I'm going to be replacing the SRAM batteries in some old game cartridges and I'd like to touch as little as possible. I know from experience that water-soluble flux corrodes metal readily if left on the board but I was hoping that rosin-core flux was different in that regard. I've gotten cheap boards that were soldered with rosin flux that was left on and there didn't seem to be any corrosion or shorting. I had done some quick research and found people saying that rosin flux residue was supposed to be safe to leave on but I'd be willing to trust people here more. BattleMaster fucked around with this message at 10:44 on Feb 25, 2015 |
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Feb 25, 2015 10:23
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PDP-1 posted:I'm trying to get a Newhaven Display NHD‐0420CW‐AB3 4x20 OLED display running over I2C and I must be missing something stupid because I can't get the screen to turn on. I have it wired up for a 5V I2C connection as shown on page 4 of the PDF, and I can see on the oscilloscope that the device is sending an ACK bit when it should so the device must be listening and I should have the bus address right. Are you 100% sure it is ACKing? Possible confusion of 7-bit vs 8-bit addressing?
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Feb 25, 2015 17:10
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I'd try an I2C scan to see if it's an address issue. I think I've used this example before: http://playground.arduino.cc/Main/I2cScanner
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Feb 25, 2015 19:05
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BattleMaster posted:I'm going to be replacing the SRAM batteries in some old game cartridges and I'd like to touch as little as possible. Good quality flux (no matter if it's water or rosin-based) shouldn't cause corrosion readily, unless you are using acid flux, which is a no no. I use either MG Chemicals, SRA, or Kester. To remove, use flux remover. Alcohol, even 99% isopropanol, saturates at like 3% with flux. Plus it's hygroscopic, so it'll attract water in the bottle, and the water can cause issues on the board. Proper Flux remover isn't expensive. Use a flux brush to scrub, tilting the board so the excess runs off. If you see any white residue remaining, clean it again. A can of duster does wonders for drying the board.
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Feb 25, 2015 21:20
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movax posted:Are you 100% sure it is ACKing? Possible confusion of 7-bit vs 8-bit addressing? If you got a scope I find that usually answers my I2C questions pretty quickly. If you're still stuck start decoding packets and make sure everything looks kosher.
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Feb 26, 2015 01:57
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sharkytm posted:Good quality flux (no matter if it's water or rosin-based) shouldn't cause corrosion readily, unless you are using acid flux, which is a no no. I use either MG Chemicals, SRA, or Kester. Well when I say "readily" I don't mean that it causes the metal to corrode right before my eyes, but that it will happily turn the copper green after some time if left on. But mainly I was hoping to avoid both corrosion and having to go at an old PCB with irreplaceable chips with a wire brush or liquid.
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Feb 26, 2015 02:09
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movax posted:Are you 100% sure it is ACKing? Possible confusion of 7-bit vs 8-bit addressing? Stabby McDamage posted:I'd try an I2C scan to see if it's an address issue. I think I've used this example before: http://playground.arduino.cc/Main/I2cScanner Popete posted:If you got a scope I find that usually answers my I2C questions pretty quickly. If you're still stuck start decoding packets and make sure everything looks kosher. e: Problem solved, it looks like we just got a bad unit out of the box. I bought a replacement and swapped it in and it came right on. There's a voltage converter inside the unit to drive the OLED display, it must have been bad but the microcontroller was working so I could talk to it all I wanted but it couldn't turn on the display. I got a trace off our MDO scope, it looks like the ACK is there despite a small rump pulse where the listener may be releasing the line a bit early. Ox3C is the correct address, the write bit is there, 0x80 means you're about to send an instruction and 0x0F tells it to turn on the display. The MDO scope notes any NACK signals it spots and it isn't showing any.  I found a forum on the manufacturer's website where their engineers seem to be pretty active about responding to questions, tomorrow I'll try posting the scope trace and how I have it connected and see if there's anything they can spot. Thanks for the suggestions! PDP-1 fucked around with this message at 23:40 on Feb 26, 2015 |
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Feb 26, 2015 03:08
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I've got a 13 pin DIN connector, so I bought a 13 pin din plug so I could make a wire to connect to a ham radio, but i've kinda got a problem, any cable i've made up before the plug has had like solder cups to connect to, this is just 13 pins all 0.1" apart from each other, what's the best way to connect to this, because I don't think I can solder 13 wires that close without ending up in solder bridge hell, and also melting through insulation etc as I struggle with it. How do I connect this? the connector is basically this http://www.nkcelectronics.com/assets/images/din13.jpg
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Feb 26, 2015 22:24
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Crankit posted:I've got a 13 pin DIN connector, so I bought a 13 pin din plug so I could make a wire to connect to a ham radio, but i've kinda got a problem, any cable i've made up before the plug has had like solder cups to connect to, this is just 13 pins all 0.1" apart from each other, what's the best way to connect to this, because I don't think I can solder 13 wires that close without ending up in solder bridge hell, and also melting through insulation etc as I struggle with it. How do I connect this? Lots of flux, fine iron tip, heatshrink tubing...
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Feb 26, 2015 23:08
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Get some small dia brass tubing, make your own solder cups
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Feb 26, 2015 23:26
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I'm really liking how Microchip's niche for their 8-bit PICs lately has been to cram in as much analog stuff as possible. PICs have had ADCs and comparators on-chip forever, but their new (last couple of years) PIC16s with op-amps, DACs, internal voltage references, zero-cross detector, on-die temperature sensor, and more are lovely. There's a new family they just announced too that has 100mA output pins which have me excited. Anyway I'm hoping someone with more experience can help me with a couple of design questions related to analog features on PICs. First, if I need to use an on-chip op-amp as a voltage follower to buffer input to an ADC, can I leave the op-amp output pin floating (or at least with a capacitor between it and ground for some stability) and select it as an analog input for reading the voltage from? That will save me a pin versus using a separate output and separate input and jumpering them together. Second, if I need to use a comparator to check if a signal goes above/below a trip point, can I also use this pin as an ADC input if I need to read the voltage as well? This will save me a pin versus connecting the same signal to two separate pins. BattleMaster fucked around with this message at 11:22 on Feb 27, 2015 |
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Feb 27, 2015 11:19
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I've got a project i'm trying to build and i'd like one part (a handle) to plug into the other to charge. The handle would ideally power an additional part through the same 3pin connector. Is this possible? i've drawn a terrible diagram with a diode which should prevent the 12v charge going the wrong way (i think) but i think this way the battery discharges into it's own charging circuit. Do i need to use a mosfet or something to break one limb of the circuit while a certain voltage is applied?
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Feb 27, 2015 12:23
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Super easy question here. I want to slow down the DC motor on a label dispenser, I believe what I want is a PWM (instead of using a pot as these things run 24/7). The unit power supply is rated at 12V 800mA. I checked the motor and it's pulling 11.47V. I have no idea what frequency I need, but 13KHz seems like it should be enough--thus I think this should work: http://www.newegg.com/Product/Product.aspx?Item=9SIA2C51309984&Tpk=9sia2c51309984 Can someone please confirm? EDIT: 13kHz not 13Hz c0ldfuse fucked around with this message at 16:29 on Feb 27, 2015 |
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Feb 27, 2015 16:27
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Crankit posted:I've got a 13 pin DIN connector, so I bought a 13 pin din plug so I could make a wire to connect to a ham radio, but i've kinda got a problem, any cable i've made up before the plug has had like solder cups to connect to, this is just 13 pins all 0.1" apart from each other, what's the best way to connect to this, because I don't think I can solder 13 wires that close without ending up in solder bridge hell, and also melting through insulation etc as I struggle with it. How do I connect this? I assume it is meant to be used with appropriately-sized crimp pins. Look here for some ideas: http://www.jameco.com/1/3/circular-pin-connectors
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Feb 27, 2015 17:11
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Loving Africa Chaps posted:I've got a project i'm trying to build and i'd like one part (a handle) to plug into the other to charge. The handle would ideally power an additional part through the same 3pin connector. Is this possible? i've drawn a terrible diagram with a diode which should prevent the 12v charge going the wrong way (i think) but i think this way the battery discharges into it's own charging circuit. Do i need to use a mosfet or something to break one limb of the circuit while a certain voltage is applied? You're going to need to explain this a bit better, since I have no idea what parts of your system are, how they connect, or really what you're trying to achieve.
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Feb 27, 2015 17:17
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Slanderer posted:You're going to need to explain this a bit better, since I have no idea what parts of your system are, how they connect, or really what you're trying to achieve. The bottom is what i have now. A 1s lipo in a handle that connects to a small camera gives it 3.3v and gets back composite video via a 3pin pogo pin connector. What i'd like to do next is rather then take the battery out to charge add in a charging circuit and plug it into a portable monitor i'm building using the same connector and charge it like that when it's stored and not in use. 
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Feb 27, 2015 19:42
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c0ldfuse posted:Super easy question here. Assuming it's just a DC brushed motor that doesn't reverse, that PWM thingy will work fine.
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Feb 27, 2015 19:53
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insta posted:Assuming it's just a DC brushed motor that doesn't reverse, that PWM thingy will work fine. Exactly what it is. Thanks for help.
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Feb 27, 2015 20:38
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Loving Africa Chaps posted:The bottom is what i have now. A 1s lipo in a handle that connects to a small camera gives it 3.3v and gets back composite video via a 3pin pogo pin connector. What i'd like to do next is rather then take the battery out to charge add in a charging circuit and plug it into a portable monitor i'm building using the same connector and charge it like that when it's stored and not in use. Ah, that makes more sense... There may be a specialized IC for some other application that you could employ with this, but I couldn't find anything from a quick search. Without that, you'll need a bunch of stuff... You need (at least) a diode to prevent the input voltage from going into the regulator output, but you'll also need to be able to detect if the 12V is present---probably through a comparator or window comparator, with some amount of filtering if the 12V input could be noisy. The comparator would switch on a FET after a short delay, which would connect the 12V input to the charger input. Then it would need to quickly (but maybe not too quickly) shut it off again once the 12V input drops below a threshold. There may be more details that I'm missing, but that's what comes to mind...
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Feb 27, 2015 21:34
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I'm looking for a motor. Loosely robotics-related, so I figured someone here might have a motor shop in mind. Single-phase AC preferred but not required. 500RPM max. I can work with this number with a speed controller, but a 3600RPM motor is probably not going to do me any good. ~500in-lb max, more is fine, but I know I need at least 250in-lb. Ideally with a 1/4" square output shaft. Where do you guys go to shop for smallish motors? Edit: harbor freight 1/2" low-speed drill. $50 - 20% off coupon. 500 RPM max, 1700in-lb stall torque. Brushed AC motor for super-cheap speed control goodness, and it's got a chuck on the front end so the output shaft is a non-item. babyeatingpsychopath fucked around with this message at 05:08 on Feb 28, 2015 |
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Feb 28, 2015 01:40
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Slanderer posted:Ah, that makes more sense... Cheers, i'll have a look but i think it's going to more trouble then it's worth, especially as you can now get Qi chargers pretty easily which might be a better, and cooler solution
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Feb 28, 2015 08:37
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Loving Africa Chaps posted:Cheers, i'll have a look but i think it's going to more trouble then it's worth, especially as you can now get Qi chargers pretty easily which might be a better, and cooler solution Qi chargers are the most horribly inefficient power-wasting charging technology known to civilized man. That said, yes, they are pretty cool.
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Feb 28, 2015 09:46
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SoundMonkey posted:Qi chargers are the most horribly inefficient power-wasting charging technology known to civilized man. Lessons on how to build the worst transformer on earth: Any inductive charging system.
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Mar 1, 2015 09:57
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insta posted:Assuming it's just a DC brushed motor that doesn't reverse, that PWM thingy will work fine. Worked perfectly, everyone should have one of these lying around.
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Mar 3, 2015 18:57
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Forgive me if this sort of thing isn't supposed to go here but, at the moment, you can get Irwin Self-Adjusting Wire Strippers for under $16 on Amazon. I think I shelled out over $30 for mine (which were a replacement for a set that were stolen) and they are hands down the best wire strippers I've ever used.
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Mar 5, 2015 03:59
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poeticoddity posted:Forgive me if this sort of thing isn't supposed to go here but, at the moment, you can get Irwin Self-Adjusting Wire Strippers for under $16 on Amazon. I think I shelled out over $30 for mine (which were a replacement for a set that were stolen) and they are hands down the best wire strippers I've ever used. Those are the Good Ones, with the wire cutter and crimpers in the handle. I have/had a set of older ones without those two features and they were great, until they got left out on the back of someone's truck in Florida and all the teeth rusted off.
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Mar 5, 2015 13:21
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poeticoddity posted:Forgive me if this sort of thing isn't supposed to go here but, at the moment, you can get Irwin Self-Adjusting Wire Strippers for under $16 on Amazon. I think I shelled out over $30 for mine (which were a replacement for a set that were stolen) and they are hands down the best wire strippers I've ever used. Are those actually good, or are they just good compared to other auto strippers? I don't think I've ever held a wire stripper like that that actually worked worth a drat.
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Mar 6, 2015 03:35
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DaveSauce posted:Are those actually good, or are they just good compared to other auto strippers? I used to work in a cable shop that used pretty much every wire gauge you'd imagine (24ga - 4/0), and had to repeatedly strip wire jackets to a consistent length, and NOBODY had an auto stripper. I don't think the shop even had one. I could be alone in this but with like 18-10ga stranded wire, I couldn't imagine reliably stripping it without being able to get some kind of tactile feedback about how far I am into the insulation. I'm not saying these are trash or anything but yeah, haven't had good experiences with auto strippers.
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Mar 6, 2015 04:32
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DaveSauce posted:Are those actually good, or are they just good compared to other auto strippers? I've stripped everything from large solid core wire to the wires inside of ethernet cables to small ribbon cables and the rate of failure (either severing the wire or failing to strip the wire) is probably less than 2% of what it was with the last set of auto strippers I had. The adjustable depth gauge is a bit flimsy, but I usually fold it down to get it out of the way, anyways. It also works fast enough that, unlike with my old strippers, I don't feel like I need to turn off my iron to strip a set of wires, which is delightful. edit: SoundMonkey posted:I could be alone in this but with like 18-10ga stranded wire, I couldn't imagine reliably stripping it without being able to get some kind of tactile feedback about how far I am into the insulation. poeticoddity fucked around with this message at 04:35 on Mar 6, 2015 |
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Mar 6, 2015 04:33
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I have a pro's kit brand of one of those. Other than handle style, it looks identical. I used it at work, and then bought one for myself because I loved it so much.
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Mar 6, 2015 05:15
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I recently bought and completed a little "Learn-to-solder" kit from Amazon where you just solder on different electrical components and it creates a little siren that flashes when you plug a battery in. It works fine, but I found that my joints never seemed to have a nice and shiny look, nor could I get my solder to flow into my solder-wick. I used a flux pen, I have a decent soldering station with a digital temp reading and tried a variety of temperatures/tips, so I was either doing something very wrong or the 63/37 solder I got from China is junk. Does the quality of solder matter a lot? Anyone know where I can buy good solder in Canada?
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Mar 7, 2015 00:21
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Out of all the solder I've ever used I've had the best luck by far with 60/40 water soluble flux-cored solder. You need to clean the board afterward though or things will corrode, but it's easy enough. Other solders I've used haven't flowed as well or formed as good joints.
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Mar 7, 2015 00:25
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Grimes posted:I recently bought and completed a little "Learn-to-solder" kit from Amazon where you just solder on different electrical components and it creates a little siren that flashes when you plug a battery in. It works fine, but I found that my joints never seemed to have a nice and shiny look, nor could I get my solder to flow into my solder-wick. I used a flux pen, I have a decent soldering station with a digital temp reading and tried a variety of temperatures/tips, so I was either doing something very wrong or the 63/37 solder I got from China is junk. Does the quality of solder matter a lot? Anyone know where I can buy good solder in Canada? The Chinese stuff was junk, and you probably weren't fluxed enough. Get some 60/40 leaded solder with rosin-core flux, and run it about 280C.
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Mar 7, 2015 00:26
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insta posted:The Chinese stuff was junk, and you probably weren't fluxed enough. Get some 60/40 leaded solder with rosin-core flux, and run it about 280C. Also you might try some finer-gauge solder so the tiniest hand movement doesn't bloop a giant amount of solder onto the joint.
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Mar 7, 2015 00:53
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What's in everyone's benchtop component supply cabinet? With radio shacks going out of business, I recently went on a shopping spree and bought a bunch of garbage resistors/diodes/misc crap for relatively cheap. I got a few of their multi-pack resistors in various power sizes, some random ICs (555 timers, op-amps, etc.), and a few other assorted crap that remained after stuff had been picked through. If you were to go online to digi-key or something and buy a bunch of components to keep in on-hand just in case, what would you get? Also, maybe a stupid question, but where do I get banana plug cables? Seems like everyone sells solder plugs, and I hate soldering...
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Mar 11, 2015 23:48
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DaveSauce posted:Also, maybe a stupid question, but where do I get banana plug cables?
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