Introduction

Gorilla

Hi everyone.

My name is Gorilla I wanted to introduce myself. I am new to the forums and new to basic stamps. After reading a few posts I have a question.

1. what does "sync" mean?

I see people saying things like the Basic stamp project board can only "sync" 20ma etc. (I don't know how much the board can sync just an example) I also saw a post talking about syncing transistors.

Mike Green

It's not "sync", it's "sink". Look at the Wikipedia article on TTL logic (here), particularly what's called a "totem pole output". Even though the structure of a CMOS output stage is different, it functions somewhat like these with one transistor connecting the I/O pin to the positive power source and a second transistor connecting the I/O pin to ground. Only one transistor is on at a time.

When the I/O pin is connected to the positive power source, the output "sources" current. It provides "current" to the pin (not electrons ... "current" flows from positive to negative).

When the I/O pin is connected to the ground, the output "sinks" current. It absorbs current to ground (like the drain on a sink). The same term is used for a heatsink which absorbs heat from something and gets rid of it.

erco

"Sync" is synchronize. Get 2 or more things operating in unison.

"Sink" is to make a connection to ground at a specified maximum current. "Source" is to make a connection to Vdd (+5V) at a specified maximum current.

A single BS2 pin can source 20 mA or sink 25 mA. See http://www.parallax.com/tabid/768/ProductID/1/Default.aspx

edit: Apparently Mike types faster than I do, but he and I were sync'ed when we were writing our replies!