Waveshare 4.2inch e-Paper V2 User Manual page 9

Note 5-3: This pin (RES#) is reset signal input. The Reset is active low.
Note 5-4: This pin is Busy state output pin. When Busy is High, the operation of chip should not be
interrupted, command should not be sent. The chip would put Busy pin High when
-Outputting display waveform-Communicating with digital temperature sensor.
Note 5-5: Bus interface selection pin.
BS1 State
L
H
MCU Interface
4-lines serial peripheral interface(SPI) - 8 bits SPI
3- lines serial peripheral interface(SPI) - 9 bits SPI
6
4.2inch e-Paper V2
User Manual