maemo.org - Talk - View Single Post - Producing Qwerty OtherHalf --order counter: 75/75 --ordering closed

	kimmoli	2014-01-19 , 12:35
	Posts: 562 \| Thanked: 2,744 times \| Joined on Dec 2013 @ Espoo, Finland	#323

Originally Posted by dirkvl

Fixing everything

long list...

Originally Posted by dirkvl

What should I do with:
-bypass capacitors??
-pull-ups?

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.

Originally Posted by dirkvl

(personally: if it's not completely neccessary, don't complicate things)

Just make it good enough...

Originally Posted by dirkvl

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

(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)

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