Hazardous to my health

As Sam has mentioned, I find myself soldering away even though my thermo final was less than 12 hours away. Aside from the mental toll of circuit projects, I often find myself breathing in more than the desirable amount of solder fumes and pcb dust. I am sorry lungs, I will let you recover this winter break (fingers crossed). I decided to bypass all the shift register and transistors and directly power the display with the AVR. This meant careful consideration of LED brightness and current draw from the AVR pins. Since I am using 1k resistors, the maximum current draw (all 7 segments and a decimal) would only be 40mA, which is just what the pins could supply. I double check that the visibility is still acceptable when multiplexed by writing a quick script to blink the LED with a 1:5 ON-OFF ratio (there are four digitals so 1:4 is the max time ratio, 1:5 just to be safe). Oh yeah, I forgot to mention this, I screwed up the resistors, they are position upside down (you can see how I screwed up the drawing on the Post-It) so I had to redo them. That’s just the beginning, after which I had to cut the perf board and solder 16 wires in a very confined place. Anyways, the fruit of my labors:

10 resistors

drawing for resistors

wired display

wired display

wired display

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s