Hi, sorry, this is kind of a two-part issue.
-
power
-
control
I have an Artemis Redboard, and I have enjoyed trying out several of the Qwiic connect sensors, like the RFD77402 ToF.
I tried chaining 3 of them … til I read that for that sensor , there’s no way to individually address them. Somewhere it was mentioned to use a SparkFun Qwiic Mux Breakout - 8 Channel (TCA9548A).
(I would need to figure out the Arduino sketch to address each)
And that’s fine. But all of these sensors chained bring up the question of power.
I used a 12V power supply to the Artemis via the barrel plug, in addition to having a USB connection to my laptop. I noticed that it measured between 30 to 50 mA draw.
I (think, not positive) that with just the USB, the Redboard area near the barrel plug was a bit warm(er). With the power supply it seemed a bit better.
I really want to protect all my smart boards from having to power anything, and have them just be concerned with signalling/comms.
So is there some easy way to provide separate power to my sensors?
For starters, specifically using 3 RFD77402s (because either point them at different angles, or because their beams are too narrow(?) and a single sensor might miss something like a chair or table leg.
Later I would want to add HCSR04 acoutic sensors that I also got with the Qwiic connect.
any tips appreciated.
thank you.
Hi ecorrales,
The 3.3V rail on the RedBoard Artemis can source up to 600mA so unless your total draw of all the sensors attached to the Qwiic connector exceeds that, you do not need to worry about providing an external source. If you are really concerned about powering all the peripherals from the RedBoard, the best option would be to not use the Qwiic connector and instead solder to the header pins broken out on the side of your Qwiic sensors/peripherals to allow you to connect them to an external source.
If you are concerned about excess heat and stressing the voltage regulators, you actually want to power the RedBoard Artemis either via USB or with a voltage closer to 5V. With voltage regulators, a large voltage drop (eg. 12V to 5V) will tax the regulator more than a smaller voltage drop (eg. 7V to 5V) so if you decide to power the board from the barrel jack, a lower voltage is ideal but 12V is also just fine.
Now, for using 3 of the ToF Sensors on a single I2C bus, you are correct, you will need to use a MUX to address each individually since the I2C address of the RFD77402 is set to 0x4C and is not adjustable. To use the MUX with these, I would recommend taking a look at the [Example Code from our Hookup Guide for the Qwiic Mux. That will give you a good demo of what your code would look like to address three of them.
Adding in the [Zio Ultrasonic Distance Sensor on the Qwiic bus should not affect anything unless you are using multiple ultrasonic sensors. You can also connect this or the other HC-SR04 Ultrasonic Sensors using the TRIG and ECHO pins attached to a digital I/O pin on your RedBoard Artemis. We have an example of how to connect this to an Arduino in our [Inventor’s Kit Experiment Guide if you want to take a look.](SparkFun Inventor's Kit Experiment Guide - v4.1 - SparkFun Learn)](Zio Ultrasonic Distance Sensor - HC-SR04 (Qwiic) - SEN-15171 - SparkFun Electronics)](Qwiic MUX Hookup Guide - SparkFun Learn)