Handwiring Posibility?

Hello and thank you very much for your work, honestly it's brilliant!

Since not many people have access to PCB manufacturing / KiCad skills or want to make something like a dactyl keyboard (my usecase), are there any resources available or any way that people can start looking it up in terms of wiring?

Thanks again!

[Dracozny]

Anything is possible, I have actually thought about this in regards to making a Melodicade. The creator of that device solders the cherry switches with wires to his Teensy 4.1. You could look at modifying the base of the Scad to snap in the 4e hall sensor into the base and then solder the leads from that.

[luqtas]

there's no way to make a physical connection when the magnet is lowered? or the hall sensor is the best bet?

[RussNelson]

Hall sensors work great. With the analog kind, you can adjust exactly where the trip point is.

[luqtas]

Hall sensors work great. With the analog kind, you can adjust exactly where the trip point is.

so that would involve diodes? as i couldn't find frameworks like QMK interpreting analog signals...

[RussNelson]

The analog hall sensors require an A/D input for each key. Practically, you need to use an A/D multiplexor.

[RussNelson]

Sparkfun just pointed me to this product: https://www.sparkfun.com/products/23880
It's an analog hall effect sensor which is interfaced via I2C ! So you wouldn't need a boatload of analog multiplexors, just the ability to read the I2C fast enough to sample all the keys. Also, because I2C is a bus, the keyboard layout would be much simpler.

[luqtas]

can't we use something like a 74HC4051 8 channel Analog Multiplexer and link it at a ROW or COLUMN then parse to software like QMK/KMK? at least of from my reads, we can define a custom matrix for I/O expanders...

[Dracozny]

@russ that boar is 1x1 inch. if you are using it for a PC keyboard option such as Risk you will find it very cumbersome. I would look of or alternatively engineer an option to have multiple sensors on a board.to me the multiplexor makes more sense but if you want to route from a multiplexor to another chip to do an I2S transport to your microcontroller, that could be doable and likely wouldn’t impart too much latency. cost wise though I think it may be the more expensive option. @luqtas, that is a doable solution. I personally am using a multiple 74HC4067 with a Teensy 4.1 as my project has over 160 buttons.

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On Mon, Jan 8, 2024 at 2:08 PM luqtas ***@***.***> wrote: can't we use something like a 74HC4051 8 channel Analog Multiplexer and link it at a ROW or COLUMN at software like QMK/KMK? at least of from my reads, we can define a custom matrix for multiplexers... — Reply to this email directly, view it on GitHub <#13 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA2PC6GAAQ5HDXTKKT3STS3YNRU4LAVCNFSM5QVNSKN2U5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TCOBYGE4DSOBSHA3A> . You are receiving this because you commented.Message ID: ***@***.***>

[RussNelson]

@Dracozny It's about the chip, not the board. You would of course put it onto a keyboard PCB.

[Dracozny]

Sure. In any case looking at the datasheet you will want to keep this tidbit in mind " 7-bit default factory I2C address is loaded from OTP during first power up. Change these bits to a new setting if a new I2C address is required (at each power cycle these bits must be written again to avoid going back to default factory address)." Looks like there are 4 addresses preprogrammed already. " 7.3.4 Device I2C Address Table 7-2 shows the default factory programmed I2C addresses of the TMAG5273. The device needs to be addressed with the factory default I2C address after power up. If required, a primary can assign a new I2C address through the I2C_ADDRESS register bits after power up."

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On Tue, Jan 9, 2024 at 11:44 AM Russ Nelson ***@***.***> wrote: @Dracozny <https://github.com/Dracozny> It's about the chip, not the board. You would of course put it onto a keyboard PCB. — Reply to this email directly, view it on GitHub <#13 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA2PC6GMLCCVHJEDHD6SU4LYNWMYNAVCNFSM5QVNSKN2U5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TCOBYGM3DOMZWG44A> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[luqtas]

ok... so i decided to take a look at the sensors again, as i had a doubt of wiring them like one would do with a standard switch! so there are various models, do we have any noob guide which informs the type of output? all i could find was technical documents that i couldn't identify if the bit was parsing a digital signal or not 😁

A3141, A3142, A3143, US1881, OH090U, A3144; can i hand-wire with one of them, without using a multiplexer? ¶ which is my best bet? as i saw A3144 with a diode and a capacitor at diagrams found at the internet... the most clean/simple solution is the one i'll go