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#1 2010-02-01 00:50:12

jox
New member

Simple scheme of Analog Acquisition. About the ground reference.

Hi everyone
ÁChameleon has two ground pin (near  screw 1 and 18) and two positive power (+5u and +5b).

Someone know what is the difference?

I obtain the analog signal that i need to measure with a simple voltage divider but using an external 12V power supply (that is the same that i'd like to use for ÁChameleon external power) . 

Is possible to connect the negative of 12V external power supply to the GND pin of ÁChameleon?

thanks

Last edited by jox (2010-02-01 00:50:38)

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#2 2010-02-08 23:01:21

AlanH
Member

Re: Simple scheme of Analog Acquisition. About the ground reference.

If you are going to use the power supply to power the chameleon then you will al ready have effectively connected the gnd.  When you use an external power source your circuit ground ref. point is the external supply.

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#3 2011-10-18 10:20:49

gremlinc5
Member

Re: Simple scheme of Analog Acquisition. About the ground reference.

jox wrote:

Hi everyone
ÁChameleon has two ground pin (near  screw 1 and 18) and two positive power (+5u and +5b).

Someone know what is the difference?

Hi,

Measured with a Digital Multimeter on a uChameleon USB Bus Supply Powered:

+5u with GND = 5.10 volt
+5b with GND = 4.85 volt

GND near pin 1 and GND near pin 18 = 0 volt

+5u is from USB cable
+5b is from voltage regulator (disabled because USB power supplied)

jox wrote:

I obtain the analog signal that i need to measure with a simple voltage divider but using an external 12V power supply (that is the same that i'd like to use for ÁChameleon external power) . 

Is possible to connect the negative of 12V external power supply to the GND pin of ÁChameleon?

thanks

No I don't think so:
If you put signal to ADC between 12 and 0 volts, you couldn't use a 0 and -12 power supply for uChamy. But you could duplicate 12 0 and use it for uChamy and external circuits.

Last edited by gremlinc5 (2011-10-18 11:14:41)


ST7FLite39 daughter board
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"uChameleon" as: SPI Master for debug, Analog output for sensing emulation

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