Neyolight
Full Member level 5
Hi
Let me begin by explaining what I have: LC Oscillator , PIC , UART.
The LC Oscillator oscillates at a frequency (120 KHz in my case) --> This frequency is converted to a digital wave for PIC to read ---> PIC reads the rising edges of the digital wave in a fixed time ( Frequency) ---> This value is sent to my laptop.
Ok now to the strange part, previously I had no common ground b/w the LC oscillator ( which is on a breadboard right now) and my PIC ( on a PICDEM2 PLUS board). I use to read random values , much lower my current frequency (120Khz).
Today ( infact just now) I added a common ground b/w the LC oscillator ( on breadboard) and the PIC by connecting the Vss of the PIC to -ve end of the breadboard. The PIC is powered by 9V DC ( AC_DC regulator) and the breadboard is powered by 9V battery (Energizer).
So with the common ground I see '0' on my UART output and without a common ground I get 1500 -1800 values on my laptop!
Why is having a common ground giving me 0s ?
The input I see on PIC hasnt changed after common ground, its still 2.4 V with 120 Khz.....then is UART affected so badly by common ground?
Any idea as to why that is happening?
Thanks
Let me begin by explaining what I have: LC Oscillator , PIC , UART.
The LC Oscillator oscillates at a frequency (120 KHz in my case) --> This frequency is converted to a digital wave for PIC to read ---> PIC reads the rising edges of the digital wave in a fixed time ( Frequency) ---> This value is sent to my laptop.
Ok now to the strange part, previously I had no common ground b/w the LC oscillator ( which is on a breadboard right now) and my PIC ( on a PICDEM2 PLUS board). I use to read random values , much lower my current frequency (120Khz).
Today ( infact just now) I added a common ground b/w the LC oscillator ( on breadboard) and the PIC by connecting the Vss of the PIC to -ve end of the breadboard. The PIC is powered by 9V DC ( AC_DC regulator) and the breadboard is powered by 9V battery (Energizer).
So with the common ground I see '0' on my UART output and without a common ground I get 1500 -1800 values on my laptop!
Why is having a common ground giving me 0s ?
The input I see on PIC hasnt changed after common ground, its still 2.4 V with 120 Khz.....then is UART affected so badly by common ground?
Any idea as to why that is happening?
Thanks
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