Uni-Byte 0195 - ANALOG Keyboard from Start to FINISH (Modular Design)
ฝัง
- เผยแพร่เมื่อ 30 ก.ย. 2024
- High quality, low cost PCB prototypes: www.pcbway.com
In this video, fifth in our Modular Design series, we'll design a Analog Keyboard Module to add to our module library and to be used in our final project in the series. We'll take you through the entire design process from start to finish.
Buying from Amazon or AliExpress? Use these links to help the channel and it won't cost you a penny more!
Amazon Affiliate Link: amzn.to/49GmnRV
AliExpress Affiliate Link: s.click.aliexp...
Help support the channel directly.
Through PayPal: paypal.me/UniB...
Or click on the Super Thanks button above (heart with a "$" sign)
My uploaded projects at PCBWay: www.pcbway.com...
Video Specific Links:
Modular Design: • Modular Design
Subscribe: / @uni-byte
Nice tutorial.
If ever you are stuck for a starting point, try copying your breadboard layout onto the screen. Same as with soldering, start with the largest component(s). Its all relocatable along the way.
Good tip!
Pardon? You don't need a trace connecting the two pins of each switch with each other, they're internally connected by the leadframe, the trace you drew is redundant. It's so forthcoming of switches to serve as an extra layer on the PCB. The connection from the south of 100nF to south of J1 can just loop underneath the 10k resistor, or the resistor can be moved to live between J1 and 100nF. Am i reading something wrong?
Also at high frequencies, your switch-common net, the S net on the connector, is effectively ground due to the capacitor coupling it in :D So you can make the whole bottom pour just that. :D
Yes, I think you are reading things wrong. Sorry, but this comes from assuming you are better than others, I think. 🤣 The reason the trace is all the way though is so that if I want to build up one with only 1, 2 or 3 switches it will still work without me having to add jumpers. Add to this that there is absolutely no advantage here to having a ground plane with this application. It's just something I try to do if I can without compromising something else because in a lot of cases it is advantageous..
High frequencies??!! What are you talking about? How fast can you press buttons? There are no high frequencies. Copper pours and ground planes require the deposition of more copper, unless there is some real advantage to them (heat sink, shielding, reduced supply impedance, reduced signal impedance, etc. - non of which we have here), or it does not compromise anything but maybe a good exercise to do it, then why do it?
@@uni-byte Haha you don't have to get this combative :D it's all in good fun. It's not like i don't make ugly boards :D
I see your reasoning with through traces, the blue topside ones. The red bottom ones connecting two sides of the switch with each other are still redundant even if you want to leave switches unpopulated, might give you a little extra routing freedom, doesn't really help in this instance though. The S net can run the south side of switches for example if you were willing to put all the resistors on one side of the switches, which you might not want to. I mean there's no point nitpicking this board, i just do it for fun, not because it's bad or needs fixing.
Indeed you don't need a ground plane. But you said you like having one, sooo... there's that then i guess if you wanted.
Even if deeply entirely completely irrelevant, you're mistaken that there are no high frequencies on this board. The switching action at the moment of switching creates a pulse which is a frequency band from DC to infinity, and seen over a short enough time frame, the high frequency band is significant. And switch bounce adds to that. Sometimes it's worth keeping in mind, though not this time. Here you're having the capacitor take up the high frequency band and short it to ground, which is presumably why you installed it, aids with debouncing and makes for a much nicer better input read.
@@SianaGearz Not really trying to be combative, just giving back in kind with a little amplification, if you will. All's good with me.
Interestingly enough, A&R Cambridge (aka Arcam of high-end audio fame) used the same idea in the Arcam Solo CD/Receiver/amp that cost over £1200 new in 2005. I restored one the other day for a charity shop I volunteer for. I had to replace all the tactile switches in the chain, as the contacts had tarnished and the additional resistance confused the machine. Apparently they all suffer from this.
Thanks. That's interesting. While I like their idea I'm not sure their implementation matches the sticker price. On something like that they should have a better quality switch.
If you have tracks on one side why can't you have a copper pour (Ground) please ?....cheers
That's just it, I couldn't get all the tracks on ne side. Really this is for high speed circuits (which this is not) but a ground plane needs to be free of traces, especially in teh case where the traces running on the ground plane side intersect traces running on the other side. The return path for current in a ground plane follows right under the signal trace. So if that path is broken by a trace on the ground plane side it actually ends up being a high impedance ground return.
Also, another interesting I found out from my contacts at PCBWay, the do not etch the boards to remove copper. The traces are actually deposited on, so not adding copper pours where they are not needed is actually saving copper and hence the environmental impact.
@@uni-byte WOW ! thats a big deal I wonder if other manufacturers do that ! I shall check. so if you want a copper pour using Dip Trace you can it's just you prefer not to. My question wasn't worded well I'm a Kicad Fanboy and I thought DipTrace wouldn't let you thats all !. The ground plane or no ground plane argument will run forever. As you say doesn't matter in this case but I personally like to use a pour top and bottom and until now that was also to aid the environment and that may not be the case....cheers :)
@@andymouse Correct, in this case I chose not to as there was no use to it. Cheers
@@uni-byte thanks!! fascinated by the deposition process and want to know more but it's getting late in the UK !! so bed time!..cheers :)
Good project for a first time designer. I would have liked to know what the purpose of this keyboard is, though, and why you chose this design over other possible implementations.
Thanks. While I'm not exactly a first time designer I choose this design because it's easy to understand how it works, it's easy to build, it's reliable and it uses easy to find (almost ubiquitous) inexpensive parts. The purpose is to provide a 4-switch input to a microcontroller using just a single analog pin. (I thought I mentioned that in the vide?). What other ways would you suggest doing this?
@@uni-byte I meant that for your audience. I didn't mean you are a first time designer!
Serial data would be another way to go (I2C for example), but since you only have an analog input, that wouldn't be a good fit.
@@yeroca Gotcha. Yes, this is aimed at the beginner. As to using I2C or other serial input I would certainly consider that for more switches. 74HC165 shift registers could be cascaded to provide input for any number of switches but I think you'd need at least 3 pins (clock, data and latch).
@@uni-byte check out "1-wire protocol", which is an async protocol, not needing a separate clock.
@@uni-byte Huh not a first time designer, could have fooled me :D