Microcontrollers and YOU!

I haven't posted in a while so i figured i'd get back into the swing of things by posting a short post on the pic's internal weak pull up resistors.

What are pull up resistors?

A pull up resistor is a fairly high resistance (usually 1K for TTL and 10K for CMOS) resistor to pull a pin to a high logic level. This is very useful as this prevents your logic levels from floating between 1 and 0. This also lets to prime a pin to a certain logic level and have an event (such as a button press) be used to then pull your pin to another logic level.

You can also pull pins down to ground if you desire using the same method (except hooking the resistor between the pin and ground instead of the pin and vdd)

For the pic16f690 you can enable WPA by clearing bit 7 of OPTION_REG (cleared by default) and setting the appropriate bits in the WPUA(bank 1) and WPUB(bank 2) registers.

This feature is extremely useful in keeping more hardware inside the pic and using as little external hardware as possible.

Often you will pull up a pin to vdd and have a button press short the pin to ground (making the pin a 0) instead of having an external resistor you can just use the on-chip WPA resistors.

So, just a short write up for now, but i have plenty of stuff coming in the next coming weeks.

I would like to introduce the PIC18 line of microcontrollers and begin posing some more sophisticated tutorials.

I will also be updating the circuit blog to include some soldering advice.

Most importantly, i need suggestions and comments, if there is a guide you would like to see, please don't hesitate to ask!

I'm looking forward to the next year to bring even more exciting content to my blog!