- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Hello everyone.
I've been trying to implement a non-inverting amplifier for a couple of days without any success.
The kit I'm using is the PSoC 4200-BLE kit, CY8C4247LQ-BL483.
This is the example Opamp project I'm evaluating:
The input signal:
The yellow is the input signal and the blue one the output.
The thing is I've noticed the Vout hasn't the same frequency as the input signal. Furthermore, the oscilloscope can't even read it because it seems to change randomly.
This was the best result I could get and it was using 800mV sinewave as the Vin+. If I change this value, the Opamp doesn't amplify at all.
For example using 200mV as input:
Any ideas of why isn't it working properly?
I get that the Opamps inside the PSoC are single supplied so they can't amplify the negative side of the sine wave and the top of the output gets clipped because of the reference Voltage. Is it possible to change Vref from 3.3V to 5V internally so the Opamp can amplify up to 5V?
Thanks!
Solved! Go to Solution.
- Labels:
-
BLE
- Tags:
- opamp
- psoc 4 ble
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Hi,
I tried this with CY8CKIT-044 (CY8C4247AZI-M485).
I noticed that there were a few points we can make mistakes
(1) Vout is needed to be an Analog Pin instead of a Digital Output Pin.
(2) Output of the Opamp must be "Output to pin."
(3) In the main.c, Opamp_Start() must be called.
I copied your schematic
Vout
Note: Vout is not a Digital Output but another analog pin Flipped Horizontally
Vplus and Vminus
Opamp
Pins
main.c
Oscilloscope waveforms
Note:
The upper RED signal is the source 0.8Vp-p 1kHz Sine Wave generated by FRDM-KL25Z.
The lower Yellow signal is the Vout
both has 0.5V unit.
moto
P.S. I tried to intentionally made the mistakes above.
(1) and (2) could not be compiled.
(3) the result waveform looked like your waveform. (Output was flat)
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
efav,
You have ground loop so your 1kHz is floating against PSoC voltage at 50Hz. Thats why you see those splashes of outputs. You must connect the grounds of PSoC board and sine generator
Secondly, the sine generator provides +/- voltage centered around 0V, but the Opamp has reference voltage Vss=0, so only positive half of the Sine will be amplified.
/odissey1
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Hello BoTa, I've connected Oscilloscope Channel1(-), Channel2(-) and Oscilloscope GND to the dev kit board's GND.
Still no success, now this is what I get:
thanks!!
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Hi,
I tried this with CY8CKIT-044 (CY8C4247AZI-M485).
I noticed that there were a few points we can make mistakes
(1) Vout is needed to be an Analog Pin instead of a Digital Output Pin.
(2) Output of the Opamp must be "Output to pin."
(3) In the main.c, Opamp_Start() must be called.
I copied your schematic
Vout
Note: Vout is not a Digital Output but another analog pin Flipped Horizontally
Vplus and Vminus
Opamp
Pins
main.c
Oscilloscope waveforms
Note:
The upper RED signal is the source 0.8Vp-p 1kHz Sine Wave generated by FRDM-KL25Z.
The lower Yellow signal is the Vout
both has 0.5V unit.
moto
P.S. I tried to intentionally made the mistakes above.
(1) and (2) could not be compiled.
(3) the result waveform looked like your waveform. (Output was flat)