• Highlights
  • BLOG
  • About
Menu

rhb.me

projects, prototypes, proselytizing and procrastination
  • Highlights
  • BLOG
  • About
16x32LedMatrixCurrent

16x32 LED Matrix Power Consumption

May 23, 2012

Following up on my LED Matrix bringup post - as I am using the Source Measure Unit (SMU) as my 5V power supply, I can quickly measure the 5V current draw of the LED matrix under different clock and pixel data conditions. Of course, these measurements are from one LED panel at room temperature - not a large enough sample set for setting specifications.   But this data can be a rough estimate, useful if you're planning a portable LED matrix application.  (click to expand)

16x32LedMatrixCurrent

Notice that the LED panel current consumption decreases as clock frequency increases.  This suggests that the LED 'on time' is decreasing.  I'm guessing this is caused by frequency-invariant delays in the LED driver shift registers.

For example, the output of the LED driver shift registers may be updated a fixed 50 nanoseconds after latching the data (for any clock rate), whereas I start loading the next line exactly 6 clock periods later.  As I increase the clock rate (decreasing the period), the time between latch + 50 ns (LED on) and latch + 6 clock periods (LED off) becomes shorter.  I need to track down a datasheet for these parts to see if this holds water.

Less LED 'on time' per time unit should also decrease in the perceived brightness of the display, I'll take another quick video to demonstrate this affect.  I didn't notice this during my initial testing, but I was not cycling through clock rates with a fixed display pattern (and the display is really bright so I wasn't looking directly at it too much!).

In Hardware
← 16 x 32 LED Matrix Panel - How do they work?Austin Mini Maker Faire 2012 →

Latest & Greatest

Featured
Dec 29, 2014
My First Dronie
Dec 29, 2014
Dec 29, 2014
Dec 17, 2014
San Juan Islands Ferry Hyperlapse
Dec 17, 2014
Dec 17, 2014
Feb 5, 2013
LabVIEW Interface For Arduino on Leonardo
Feb 5, 2013
Feb 5, 2013
Nov 24, 2012
Fun with a Waterjet at TechShop
Nov 24, 2012
Nov 24, 2012
Nov 12, 2012
Measuring AA Battery Life for LED Pixel Halloween Costume
Nov 12, 2012
Nov 12, 2012

Fresh Tweets

  • RT @itsDanielSuarez: Publishers Weekly's review of my new book CHANGE AGENT makes *me* want to buy a copy. :-) https://t.co/yyCbIlYHvj https://t.co/f6CZCMR0DO
    about a year ago
  • RT @Jason_Rubin: Bards Tale was one of the first games that I got lost in. I've been a Brian Fargo fan for 30+ years and a friend fo… https://t.co/i7GkJ83Unw
    about a year ago

Powered by Squarespace