Watergius's Journal

The world as I see it

voltage changing using ADC in MSP430

This thing happened quite a long time a go, but I think I just want to write it anyway.

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I was trying to use two ADC10 inputs in MSP430G2231 in order to produce a controllable PWM. This is the schematic for ADC inputs that I used (using simple voltage divider) :

ADC10 inputs

And it’s working. I mean, it can produced PWM. Then, I decided to check the voltage in ADC inputs. First, I check each voltage in voltage divider output (ADC1 and ADC2). After that, I connect the voltage divider to the ADC input port in MSP430G2231 (P1.0 and P1.1) and check the voltage back.

MSP430G2231

Here was the result that I got:

first measurement

Then, I tried to improvise by turn off the power source (both MSP and Voltage divider) for a short time and turn it on again, then measure it back. This was the result that I got:

second measurement

But, if I turn of the power source (both MSP and Voltage divider) for quite a long time and turn it on again , the result was like the first measurement (before I turn it off).

Okay, this was not what I expected… Still got no clue, I decided to ask about it in a forum. Luckily, I got a quick response and it turn out that the solution was really simple.

Here’s what he wrote:

Are the Rx, Tx, and LED0 jumpers in place? Remove them and test again.

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Following his suggestion, now my problem has been solved. Looks like even the tiniest thing sometimes can cause big problem..🙂

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