GPIO pins output Voltage

Technical Discussion
1

Hello I’m struggling to find just the basic answer to my question of whether I should be getting anything more than 2.7V out of any of the numbered GPIO pins on the Ameba Pro 2?

This is my code and no matter which PIN number I use it only outputs around 2.7V… but I was hoping it would be at least 3V…

void setup() {
Serial.begin(9600);

pinMode(3, OUTPUT);
}

void loop() {

digitalWrite(3, HIGH);

}

2

Hi @Stuart_Davidson ,
Please find the table of voltage measurement below for reference. I have tested a few output pins and I am able to get 3.3V after setting output pin as HIGH using Arduino. Kindly ensure that you have a stable input power supply too. Thanks.

image
image1255×346 34 KB

3

Is there a way to validate this internally (i.e. not using an external Multi-meter)?

4

Hi @Stuart_Davidson ,
We can test with a multi-meter, 3.3V is converted from 5V input power using DC-DC buck converter. Would you mind to verify that your input power source is stable at 5V as this will directly affect the output voltage from the board? You may want to refer to the schematic diagram available on our website

5

Yep I tested the with the Multimeter and It constantly shows 2.7V on all numbered GPIO pins. I also tested on VDD pin and V_USB and they are operating within normal ranges:

IMG_0523.HEIC
IMG_0523.HEIC3024×4032 2.6 MB

IMG_0524.HEIC
IMG_0524.HEIC3024×4032 2.74 MB

IMG_0525.HEIC
IMG_0525.HEIC3024×4032 2.77 MB

This is consistent across all my power supplies, is there something obvious I’m missing or is there a faulty batch of Ameba Pro 2’s (as I’m having the same problem on two of them)?

6

Hi @Stuart_Davidson ,

Thank you for the images. May I trouble you to verify that:

  1. no large load is connected to any of the GPIO pin,
  2. GPIO pin is not configured to output PWM wave,
  3. GPIO pin is not set to push-pull HIGH internally,
  4. multimeter is set to correct range for DC voltage measurement.

If possible, would you mind to test with an oscilloscope?
Kindly use our latest version of SDK to compile and upload your Arduino code.
We will try our best to assist you but you may also want to highlight this issue to your AMB82 mini supplier.

Thank you.

7

Hi @Stuart_Davidson ,

We realized that you have been using BATT mode on your multimeter to measure the DC voltage, would you like to change to DC voltage mode (circled in yellow)? this would ensure that no additional load is added when taking voltage measurement.

image
image820×596 140 KB

2 Likes
8

I totally made silly mistake.. :grinning_face_with_smiling_eyes:. it shows the right Voltage when in DC mode.

1 Like