Screaming Circuits: Grounded in Reality?


Grounded in Reality?

LED scroller 006 thin trimmed
Looking back, I think I could have done a few things different. For example, I don't really need a separate power-on LED. I could either just not populate it, or rev the schematic a little to make it a software controlled indicator rather than hard linked to the power switch. That change would allow me to put the device to sleep. The PIC18F25K20 draws somewhere around a tenth of a microamp while in sleep mode. That being the case, I might just discard the power switch all together. Otherwise, it's cool.

I could have given each LED its own via to the ground plane too. That's supposed to reduce noise a bit. Although, this will probably never be clocked high enough to make much difference, nor used in an environment where it matters.

Duane Benson
Only half of 10 the types of people will understand


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The two chips are similar but not exact. The 25K20 is a 3v part while the 2520 is a 5v part. The 25K20 has one PWM while the 2520 has two. The memory specs are all the same. At DigiKey, the K is less expensive than the other and it comes in the SSOP package that I wanted. The thing about Microchip is that there are so many slight variations that sometimes it's difficult to choose.

Any comments on the PIC25K20 vs. the PIC2520? Seems much more powerful and cost less. Does your 2520 code transfer well to the 25k20?

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