Can't get LDR to work

More
1 year 3 months ago #7932 by GregTR
On my rev5 board running 48 I can't seem to get the LDR to work. When plugged in it reads 999 when unplugged it floats around ~630. The LDR works fine on my rev4 board on 47.

I have checked the connections and wiring and everything seems to be the way it is supposed to be.

Please Log in or Create an account to join the conversation.

More
1 year 3 months ago #7934 by GregTR
Never mind. Forgot to add the 10K pull-up resistor. All is well now.

Please Log in or Create an account to join the conversation.

More
1 year 3 months ago #7935 by Ty_Eeberfest

GregTR wrote: Never mind. Forgot to add the 10K pull-up resistor. All is well now.


Glad you got it sorted. Thanks for coming back to follow up!

Look into it later when the dust is clearing off the crater.

Please Log in or Create an account to join the conversation.

More
1 year 3 months ago #7939 by Froula
The resistor is technically not a pullup, as the circuit is analog, not digital. It is part of a voltage divider that provides a voltage level to the ADC input pin on the chip that ir proportional to the light level. Without the resistor, the LDR just pulls the input to ground.

The schematic makes this really confusing, as the resistor is in the power supply section, not by the LDR connector.
The following user(s) said Thank You: GregTR

Please Log in or Create an account to join the conversation.

More
1 year 3 months ago #7941 by GregTR
Agreed on all accounts. The schematics was indeed so confusing that I was in the middle of submitting an errata of the missing resistor when I finally located the resistor on the aforementioned power supply section.

Please Log in or Create an account to join the conversation.

More
1 year 3 months ago #7942 by Ian
Hi Greg,

indeed it is in the wrong place in the schematics, of course the reason is historical, and I'll correct it.

Please Log in or Create an account to join the conversation.

Moderators: AccutronTy_EeberfestIan
Time to create page: 0.039 seconds

Search

Tube Suppliers

Go to top
JSN Boot template designed by JoomlaShine.com