Is the teensy 4.1 compatible with this breakout board?

[finnbsch]

Hi,

I connected my Teensy 4.1 to this https://www.az-delivery.de/en/products/adapter-fur-nrf24l01 breakout board and the corresponding RF module. I connected the VCC and GND of the board to the 5V and GND supplied via USB and the signal cables to arbitrary Digital Pins. I checked that the voltage from the signal pins of the board does not exceed 3.3V. Then I connected the teensy to my computer and noticed that the computer doesn't recognize it. I used a different USB cable from before so I replaced it by the working one but it didn't help. The 3.3V line shows very little voltage and the GND to 3.3V shows 0Ohm resistance so I guess it is shorted. I will get a new Teensy but obviously I would like to avoid that in the future. Again, the only differences to before was a different USB cable and the breakout board. Is it maybe not compatible?

EDIT: I just remembered that today also I tested this https://www.az-delivery.de/products/lm2596s-dc-dc-step-down-modul-1 step down module. I configured it before to deliver 4.992V (checked with multimeter) and connected it to the VIN pin. I didn't check functionality then so I can't determine whether this could have been the cause either.

 

[MarkT]

Why not connect direct to the nRF24L01+, its 3.3V, and the T4.1 is 3.3V. Not sure what happened there, but that breakout seems to be just a 3.3V regulator and some decoupling?

 

[KenHahn]

That nRF24L01+ adapter will work fine with a T4.1 and shouldn't cause any damage if connected properly. The nRF24L01+ operates at 3.3V logic but is 5V logic tolerant on its inputs.

The main value of the adapter is to make hooking up to the nRF24L01+ pins easier since they are in an unmarked double row. The built-in 3.3V regulator does take the load off the T4.1 3.3V regulator which I would recommend.

Depending on which nRF24L01+ module you are using some such as the ones with external antenna can draw fairly high instantaneous current spikes of >100mA when transmitting which can bounce the 3.3V around a bit. I know some Arduinos can't directly power them off their 3.3V without issues.

The most likely way to kill the Teensy is to accidentally short the 3.3V pin to 5V. If you accidentally connected the DC-DC converter to the 3.3V pin instead of the VIN/5V pin even momentarily, that would do it.