I am trying to send command to NHD-0220D3Z-FL-GBW-V3 by I2C interface. from the scope, I found that it is ACKed when first byte 0xA0 (address 0x50 + write) was sent out, but second byte 0xfe is NACKed. what could be wrong? according datasheet 0xfe is prefix of every command, how could it be rejected? thanks for help.