Keyestudio KS4028 Manual page 15

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b. Its IO port is very weak in driving since it can merely handle current less
than 300mA. Therefore, do not connect it with devices operating in large
current, such as servo MG995 and DC motor or it will get burnt.
Furthermore, you must figure out the current requirements of the devices
before you use them and it is generally recommended to use the board
together with a Micro:bit shield.
c. It is recommended to power the main board via the USB interface or via
the battery of 3V. The IO port of this board is 3V, so it does not support
sensors of 5V. If you need to connect sensors of 5 V, a Micro: Bit expansion
board is required.
d. When using pins(P3, P4, P6, P7 and P10)shared with the LED dot matrix,
blocking them from the matrix or the LEDs may display randomly and the
data about sensors connected maybe wrong.
e. Pin 19 and 20 can not be used as IO ports though the Makecode shows
they can. They can only be used as I2C communication.
f. The battery port of 3V cannot be connected with battery more than 3.3V
or the main board will be damaged.
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