PAN9520 ETU Evaluation Tool
3 PAN9520 ETU
User Guide Rev. 1.0
Page 13 of 35
No.
Powering Option
Description
5 Breakout pins
For power supply, the pin 3.3
V and the pin 5 V of the breakout pin
headers can be used.
If the pin
5V is used, it is recommended to set “5 V Sel.” to “input”. This
will add a diode into the supply path, which avoids problems when
connecting USB cables.
3.4 Default Boot Mode
Workaround
Please note that the described setting shall ensure that the default application
Boot Mode is also entered directly after powering the board. This Default
Mode is also set by the ESP32-S2, but does only work, if the device is already
powered and then reset.
Please use SW1 for entering the Download Mode
Pull-Up GPIO0
It is recommended to connect a pull-up resistor on GPIO0 by placing a jumper
on the “Boot Mode” pins. This ensures that the PAN9520 boots the loaded
application directly after powering the device.
At the start-up of the PAN9520, the ESP32-S2 IC evaluates the so-
called “strapping pins”. The
default values of them are determined by internal pull-resistors of the ESP32-S2. These work
fine for start-ups caused by resets. Anyway, if the IC is powered, the pull-resistors need some
time to be configured and the device does not start in the Default Mode. This is especially
important to note for GPIO0, which configures the Boot Mode after start-up.