SparkFun Forums

[aokg0qsfm]

Hi all,

I am planning a project with the Artemis ATP and Super Wav Trigger. While the Super Wav Trigger will have its own step-down converter and is isolated from the 3.3V I2C/Qwiic line, I plan to use the Artemis ATP to power everything else, which would be:

1x SSD1306 OLED Display (roughly 25mA) via I2C/Qwiic
1x SX1509 GPIO Extender (monitoring 16 active low switches) via I2C/Qwiic
1x SX1509 GPIO Extender via I2C/Qwiic driving 12 white LEDs either in current source mode (the 8 mA per pin are plenty in terms of brightness for me, so that would be roughly 100mA via the I2C connection) or current sink mode (which the manual says is more efficient) with connecting VCC1 and VCC2 to the 3.3V of Artemis ATP and using an appropriate resistor per LED to keep current in 5 mA range per LED.
1x CD74HC4067 with 12x 10k pots connected to 3.3V
Two more pots and an indicator LED directly connected to the GPIO pins of Artemis ATP.

I've read that the Artemis can set the current on a per pin basis from 2 to 12mA (so this would be the maximum per pin?). But I haven't found any infos on what is the maximum current the Artemis ATP can provide to peripherals. What can I draw maximum from the 3.3V pin safely (is it LM317-based, so 1.5A?)? What are the Artemis ATP GPIOs capabilities to sink current? Is there anything I should be aware of ? Another question concerning the SX1509: In order to daisy chain them, I can just connect one board to the next one via their input headers, right?

Thank you!

[YellowDog]

On your SX1509 question, yes you can daisy chain the boards end to end. Just make sure each has a unique I2C address.

[paulvha]

According to the datasheet, an Apollo3 processor can provide max. 12mA, either source or sync current. When setting a GPIO with pinMode() 12mA is set by default.

There are 4 pins that can be used with a max 100mA (Power Switch mode): Pads 3 and 36 have selectable high side power switch transistors to provide ~1 Ω switches to VDDH. Pads 37 and 41 have selectable low side power switch transistors to provide ~1 Ω switches to VSS. If you want to use it look at information and examples on https://github.com/paulvha/apollo3/tree/master/APgpio.

According to the schematics, the Redboard-artemis ATP is using an AP2112-3.3V, which can provide a max of 600mA. See "schematics" in "documents" on the page https://www.sparkfun.com/products/15442.

[aokg0qsfm]

Perfect, thank you all for the answers! I could daisy chain the 2x SX1509 like via their headers (with individual addresses) and the Artemis ATP seems to be able to handle enough current that I need (I'm using 2.2K resistors for the LEDs which should reduce current to 1.5mA/LED, so 20mA total - still plenty bright for me).