Current rating info. for some of the popular boards.

This post is a short summary of the source and sink current of some of the popular boards.


Arduino (ATMEL ATMEGA328)

ARDUINO PIN CURRENT LIMITATIONS:
https://playground.arduino.cc/Main/ArduinoPinCurrentLimitations

Pin SOURCE Current Limitations:

NOTE: Although each I/O port can source more than the test conditions (20 mA at VCC = 5V, 10 mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed.

The sum of all IOH, for ports C0 - C5, D0- D4, ADC7, RESET should not exceed 150 mA.
The sum of all IOH, for ports B0 - B5, D5 - D7, ADC6, XTAL1, XTAL2 should not exceed 150 mA.
If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current greater than the listed test condition.

Pin SINK Current Limitations:

NOTE: Although each I/O port can sink more than the test conditions (20 mA at VCC = 5V, 10 mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed:

The sum of all IOL, for ports C0 - C5, ADC7, ADC6 should not exceed 100 mA.
The sum of all IOL, for ports B0 - B5, D5 - D7, XTAL1, XTAL2 should not exceed 100 mA.
The sum of all IOL, for ports D0 - D4, RESET should not exceed 100 mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition.


Mediatek LinkIt Smart 7688 (MT7688)

GPIO Maximum Current
https://zh.forum.labs.mediatek.com/t/gpio-maximum-current/422

- MT7688 GPIO source current is 4mA.
- MT7688 GPIO sink current?


ESP8266 (ESP8266EX)

ESP8266 - GPIO Maximum current Imax
http://bbs.espressif.com/viewtopic.php?t=139

- Source current: 12mA per GPIO pin.

- Drive capacity current of all GPIO pins total can be 16 x 12 mA.

- Sink current: 20mA per GPIO pin.

Raspberry Pi

Raspberry Pi GPIO pin max current
https://www.element14.com/community/thread/20982/l/raspberry-pi-gpio-pin-max-current?displayFullThread=true

A maximum of 16mA per pin with the total current from all pins not exceeding 51mA.

When the Pi was designed, they used a figure of 3mA per GPIO pins in determining if the regulator could supply enough current. Hence the simple 3mA limit mentioned before. However, if not all the pins are supplying current then you can divert those pin’s share of the current into the ones you are using. Hence the total recommended current limit of 17 * 3 = 51mA.