# Re: current control algorithm

*From*: hamilton <hamilton@xxxxxxxxxxx>*Date*: Tue, 04 Oct 2011 07:15:25 -0600

On 10/4/2011 6:33 AM, Jon Kirwan wrote:

On Tue, 04 Oct 2011 07:29:25 -0400, Walter BanksNot every textbook solution is RIGHT.

<walter@xxxxxxxxxxxxx> wrote:

Tim Wescott wrote:

On Mon, 03 Oct 2011 13:58:06 -0700, cerr wrote:

Hi There,

I have two strings of 5 LEDs and a I need to control them with a pwm to

reach a certain intensity (I can measure the current). Now due to lack

of time , I didn't go with a PI controller (which I think would be the

right way) instead, I just calculate a hysteresis of x counts (10bit

adc) and the measured current has to be within this hysteresis. Now I

unfortunately got a high jitter on my LED current (that's controlled by

the duty cycle) - I assume this is because of a time delay from the time

i set the duty cycle until i measure the current rise/fall. How do I

best go about this? Is there a quick method to resolve this or do i

actually need to take the time to study and implement a PI controller?

You just need integral control, which is dead easy.

If I tried to count the number of times I've wasted far more time on a

"time saving simplification" than I ended up spending finally doing a

control loop right, I'd run out of fingers and toes before I even

finished accounting for the first few years of my career.

--

www.wescottdesign.com

One of the first big engineering projects I worked on had a

blackboard that acquired anonymous one liners. One of these

gems has stuck with me for more than 30 years.

"If you have enough time to do it over how come you

didn't have a enough time to do it right?"

Cash flow.

.

**References**:**current control algorithm***From:*cerr

**Re: current control algorithm***From:*Tim Wescott

**Re: current control algorithm***From:*Walter Banks

**Re: current control algorithm***From:*Jon Kirwan

- Prev by Date:
**Re: current control algorithm** - Next by Date:
**Re: current control algorithm** - Previous by thread:
**Re: current control algorithm** - Next by thread:
**Re: current control algorithm** - Index(es):