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| OLED Audible Noise |
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| daleykd:
Guys, I know I'm an absolute noob to all of this. I chewed off a big chunk o' project and am so close to being done, but this one issue is driving me bonkers. I've been trying to run a simple audio application, passing a guitar signal through 1/4" jacks into a guitar amp with an I2C OLED (SSD1306: http://www.ebay.com/itm/282174165223). When I run the OLED, I get some awful noise in my audio path (https://youtu.be/s9LLt7F7W4Q). As soon as I pull the OLED out, the noise is gone. I'm stumped and don't even know what questions to ask. My gut tells me that OLED just isn't nice for audio application. I'm using an Arduino Pro Micro as my MCU. |
| wraper:
OLED will have the same issue as LED matrix. As rows and columns are constantly switched, power consumption is fluctuating a lot. RF noise will be produced as well, depending on the display driver switching transition speed. Therefore you should be aware about it when laying out power rails and GND. |
| daleykd:
--- Quote from: wraper on January 07, 2017, 12:01:37 am ---OLED will have the same issue as LED matrix. As rows and columns are constantly switched, power consumption is fluctuating a lot. RF noise will be produced as well, depending on the display driver switching transition speed. Therefore you should be aware about it when laying out power rails and GND. --- End quote --- I guess it could be an issue with my PCB layout, sure. I tried so hard to keep the GNDs separated between the audio and the digital. In this case, I'm not changing anything on the OLED. Just having ANYTHING displayed (turned on) means I have the noise. Would a GLCD have the same issues? What about the 16x2 LCDs? |
| tautech:
--- Quote from: daleykd on January 07, 2017, 12:05:15 am --- --- Quote from: wraper on January 07, 2017, 12:01:37 am ---OLED will have the same issue as LED matrix. As rows and columns are constantly switched, power consumption is fluctuating a lot. RF noise will be produced as well, depending on the display driver switching transition speed. Therefore you should be aware about it when laying out power rails and GND. --- End quote --- I guess it could be an issue with my PCB layout, sure. I tried so hard to keep the GNDs separated between the audio and the digital. In this case, I'm not changing anything on the OLED. Just having ANYTHING displayed (turned on) means I have the noise. Would a GLCD have the same issues? What about the 16x2 LCDs? --- End quote --- Got a scope ? You need to find if it's coming in from RF or implied onto the PSU rails where additional bulk capacitance and/or/more bypass capacitance might solve your issue. |
| wraper:
--- Quote from: daleykd on January 07, 2017, 12:05:15 am ---In this case, I'm not changing anything on the OLED. Just having ANYTHING displayed (turned on) means I have the noise. --- End quote --- Current will fluctuate a lot as long as something is displayed. Also, I guess, pixel brightness (if there is) should be PWMed. So even if all of the pixels will display with exactly the same brightness, there still will be current consumption fluctuations. --- Quote ---Would a GLCD have the same issues? What about the 16x2 LCDs? --- End quote --- LCD itself have small current consumption, so, most likely, will be much easier to deal with. As long as there is no noisy converter for LED backlight. |
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