have 2 leds: power & debugging
debugging: run a blink program and make sure your mcu is still alive.
how to use the pin with the led? just solder pin header before or after the led.
2 layers
put pin through the board -> bam, 2 layers
you can connect then the two pins on the backside with a cable. there is no shame in that btw.
suggestion: use labels. makes your design a bit easier.
use disconnected mark in kicad if pins are not connected
use power flags if you get errors regarding power
- you need to tell kicad where power is coming into the board
- hit p on keyboard
pull-up & pull-down: check adrians doc
- if you do not connect the open switch directly to pin, there will be noise due to --- internal processes in the chip
- add pulldown resistor with low resastance so that noise rather goes to ground.
- how big pulldown resistors to be? (ricardo marques)
- for buttons you can use lke 5k,
- LEDs between 500 and 1k
- i2c depends on a few variables but between 900 and 5k.
- for 3.3v logic don't go over 2.5k
make beautiful pcb, not a square. it is the design week
- check ccc talk
make power lines of fatter thickness on a pcb
- you see it better
- signal lines you want to be thin
- thick power lines can handle more current
some more about pullup/pulldown by ricardo marques
- if you dont use pulldown pullup, there a tristate. its not defined what voltage is on the pin. internals of mC.
- this is explained further by neil in input devices
only use bat gnd and bat vin if usb is not used. otherwise they will conflict.
(source: rico)
No Comments