kimmoli | # 321 | 2014-01-19, 10:20 | Report

Tip: Add through hole (large enough) to the thermal pad, so you are able to solder it from the other side of board.

dirkvl | # 322 | 2014-01-19, 12:23 | Report

Fixing everything

What should I do with:
-bypass capacitors??
-pull-ups?
(personally: if it's not completely neccessary, don't complicate things)

And:
-4 LED's? Backlight? Green light if on? Capslock?

kimmoli | # 323 | 2014-01-19, 12:35 | Report

long list...

Few bypasses doesn't harm... specially after long cable.

I2C/INT Pullups are on the phone side (to 1.8V) so I (again) recommend using 1.8V LDO to supply TCA8424 to quarantee operation... (Datasheet: DVCC - The I2C bus should be pulled up to this rail.) Maybe it is enough to follow regulator capacitor rules, or just add one 100nF close to DVCC/GND pins.


Just make it good enough...


(at least one to see that everything is ok) Those are opendrain outputs, so can connect anode to 3.3V through resistor (just not to load 1.8V LDO)

jayki | # 324 | 2014-01-19, 12:46 | Report

I'd prefer Back light and maybe 2 Leds, one for Caps lock, if it's on and one for checking if the whole keyboard works (:
Just my opinion

dirkvl | # 325 | 2014-01-19, 15:47 | Report

Looking into this whole LDO and bypass business...

In the mean time, enjoy a royal ground plane

dirkvl | # 326 | 2014-01-19, 16:43 | Report

Okay, so for a open learning process:

Bypass/decoupling capacitors are for smoothing out electrical connections, so if an SCL line is continuously pumping out square signals , this is picked up by other parallel wires, which is bad.

So:
-Vin likes a capacitor to GND, to give the chip a nice stable power supply. Also, the LED's also like a capacitor to supply the LEDs.
-SDA, SCL and INT do not like capacitor, because the ripples in the voltages are the signal.

Next, tuning down V33 from the phone to 1.8V for the chip. This is because the SDA,SCL&INT run at 1.8V and the chip uses MIN-0.7*VCC. So, we use a linear regulator on V3.3 - with again capacitors on both sides.

dirkvl | # 327 | 2014-01-20, 11:23 | Report

Motorola keypad was in the mail today, and -although people in this topic said differently- I kind of like it!

It sticks on the domesheet, which has sticky stuff on both sides, which will make for very easy construction and thus a stronger/thinner part! The clickyness of the domesheet also feel fine!


-well spotted, that is also a fake-N900 keyboard-

Edit: it is just a but small, only 100mm wide.. Will leave 15mm gaps on both sides.

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Last edited by dirkvl; 2014-01-20 at 12:36.

Redfizh | # 328 | 2014-01-20, 12:37 | Report

I love it. Directional keys are important. Arrow-keys are not for handheld anyway.

dirkvl | # 329 | 2014-01-20, 15:40 | Report

Okay, here is the deal:

I've been going from 'hate it' to 'love it' over and forth about this Droid keyboard.
-It is a bit small, which will leave a 15mm bar at both sides, but maybe this is a good thing. My thumbs don't do yoga.
-It apparently feel rubbery, but I disagree.
-It is black and gold, what I like
-Last but definitely not least: it is available, cheap, easy manufacturing and only 1mm thick with domesheet.

I have done looking into a lot of different keyboards and the 'Ideal keyboard' thread has also not produced a suitable candidate.

Will this keyboard suffice -or in other words- would you buy it?

wolke | # 330 | 2014-01-20, 15:48 | Report

im torn between lying to try and get a better keyboard and honestly saying that it could have no vowels and id still buy it.

i would be in love with a keyboard with a number row and traditional arrow buttons.

e.g.: if you miraculously made and sold a droid-keyboard-OH, id pay 3-4x more for one with a number row.