I'm using a Teensy4.1 to drive a waveshare SSD1351 oled display attached to the SPI1 pins (just using adafruit ssd1351 library). The display works ok, but I'm getting a lot of noise on gnd (like 400mv pk-pk) whenever I try and talk to the display. This is pretty annoying as the noise is interfering with the stuff I have going on with the audio shield.
After reading a few other forum posts on similar problems, I tried turning the drive strength (IOMUXC_PAD_DSE) down on the SPI pins in SPI.cpp, but that doesn't seem to help. Setting IOMUXC_PAD_DSE(0) eliminates the noise, but the display stops working. Anything above 0 brings back the same amount of noise.
I'm having a lot of trouble tracking down the root cause of this noise problem, so I would appreciate any help.
I've attached a screenshot of the noise on my oscilloscope. I'm probing between one of the board's gnd and my battery gnd, which are both connected to the same groundplane. I'm updating the display every 10ms, which is why the noise appears periodically.
Pin Connections
(Teensy) Pin 26 -> (Display) DIN
(Teensy) Pin 27 -> (Display) CLK
(Teensy) Pin 38-> (Display) CS
(Teensy) Pin 40-> (Display) DC
(Teensy) Pin 41-> (Display) RST
After reading a few other forum posts on similar problems, I tried turning the drive strength (IOMUXC_PAD_DSE) down on the SPI pins in SPI.cpp, but that doesn't seem to help. Setting IOMUXC_PAD_DSE(0) eliminates the noise, but the display stops working. Anything above 0 brings back the same amount of noise.
I'm having a lot of trouble tracking down the root cause of this noise problem, so I would appreciate any help.
I've attached a screenshot of the noise on my oscilloscope. I'm probing between one of the board's gnd and my battery gnd, which are both connected to the same groundplane. I'm updating the display every 10ms, which is why the noise appears periodically.
Pin Connections
(Teensy) Pin 26 -> (Display) DIN
(Teensy) Pin 27 -> (Display) CLK
(Teensy) Pin 38-> (Display) CS
(Teensy) Pin 40-> (Display) DC
(Teensy) Pin 41-> (Display) RST
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