How to Power a LC from a 4.1?

SlaserX

New member
Hi team,
I have a project that uses a Teensy 4.1 as the center, but I'm also using a LC to offload some work. If I can, I'd like to power the LC from the 4.1, to reduce the amount of wiring needed going into my circuit. Is there an easy/preferred way to do this? Or should I be looking into some kind of usb hub solution to power both internally? (I'd also like to leave it open to update the 4.1 if I write new code, if that matters)
Thanks!
 
Adafruit sells the following cable. It has a micro USB-b female cable that you plug in your power/computer to, and it has two USB-b male cables. The longer cable provides both data and power, and the shorter cable provides only power. You would hook the shorter cable to the Teensy LC and the longer cable to the Teensy 4.1. I would suggest using something like a label maker to more clearly identify which cable is which:


Alternatively, If you are powering via USB, connect the VUSB pin (inside pin next to one of the ground pins) and one of the ground pins between the two boards.

If you were externally powering the Teensy 4.1 with something other than USB, you might make a Y-cable between your power, and connect one set of power lines to VIN/ground on each Teensy. IIRC, there is a soft fuse between VUSB and VIN on the Teensy, and if you connected VIN when you are powering via USB, you might have the LC limited in current (IIRC, 500 mA).

Another thought if you wanted to also incorporate communication is to use the USB host facility on the Teensy 4.1 (soldering to the 5 inner pins on the Teensy 4.1 to bring out the USB bits). I haven't done it, but I have to imagine that it should be simple to use USB host and talk to a serial device. On the Teensy LC, you would read text commands from the USB Serial connection and write out text replies. IIRC, the USB host does not provide power until you enable the USB host support (i.e. you can't just hook up a USB cable without enabling in the Teensy 4.1). One advantage of this setup is that you can more easily debug the Teensy LC by hooking it up independently to the IDE, and typing in the commands sent from the Teensy 4.1.

Typically you would solder 5 male pins to the Teensy inside row, and use this to bring out a USB A cable. You would then use a small USB A to mini USB-B cable to hook to the Teensy LC:


But you could just solder wires to those holes, and use a DIY USB micro-B plug:

 
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