Hi,
I have a Teensy 3.2 hooked up to a breadboard, and I'm working on a project that will require reading from an ADC. I was seeing some 100kHz noise (pulses) on the ADC input, so I stripped everything down to the bare essentials to troubleshoot the problem. On the breadboard now, I have just the Teensy with connections to 5V (on the VIN pin) and ground. The 5V supply is fed from a Pololu 5V 2.5A buck converter, which is fed from a 3S LiPo battery at approx. 12V. The reason for the external regulator is that the board will eventually be powering equipment that draws up to 2 amps at 5V, and I want to power this equipment in the field with a large LiPo battery.
Here's a photo of the breadboard setup (ignore the Pololu on the left, it's just an extra part, not connected to anything):
I've cut the trace to separate VIN from VUSB as indicated in this diagram (I tested with a multimeter, and there is no continuity between the pads on either side of the red line):
With this configuration, I'm seeing 100kHz pulses on the 5V supply when connected via USB to my computer (actually there's a USB hub in between):
And when I disconnect USB, the 5V supply looks much cleaner. Still not super clean, but I suspect this noise is from the Pololu, which switches at 400kHz.
At this point, I'm just running a very basic example app, nothing much going on here:
My question is: Is the 100kHz noise expected behavior, or am I doing something wrong? Is there anything that can be done to clean up that noise?
I have a Teensy 3.2 hooked up to a breadboard, and I'm working on a project that will require reading from an ADC. I was seeing some 100kHz noise (pulses) on the ADC input, so I stripped everything down to the bare essentials to troubleshoot the problem. On the breadboard now, I have just the Teensy with connections to 5V (on the VIN pin) and ground. The 5V supply is fed from a Pololu 5V 2.5A buck converter, which is fed from a 3S LiPo battery at approx. 12V. The reason for the external regulator is that the board will eventually be powering equipment that draws up to 2 amps at 5V, and I want to power this equipment in the field with a large LiPo battery.
Here's a photo of the breadboard setup (ignore the Pololu on the left, it's just an extra part, not connected to anything):
I've cut the trace to separate VIN from VUSB as indicated in this diagram (I tested with a multimeter, and there is no continuity between the pads on either side of the red line):
With this configuration, I'm seeing 100kHz pulses on the 5V supply when connected via USB to my computer (actually there's a USB hub in between):
And when I disconnect USB, the 5V supply looks much cleaner. Still not super clean, but I suspect this noise is from the Pololu, which switches at 400kHz.
At this point, I'm just running a very basic example app, nothing much going on here:
Code:
void setup() {
// put your setup code here, to run once:
Serial.begin(38400);
}
void loop() {
// put your main code here, to run repeatedly:
Serial.println("Hello World");
delay(1000);
}
My question is: Is the 100kHz noise expected behavior, or am I doing something wrong? Is there anything that can be done to clean up that noise?