Abstract: supply. ??Block diagram Kl1 Kl2 Kl3 Kl4 Kl5 KO1 (S41) Key scan buffer DO KO2 , 29 S29 Kl4 53 S4(EP4) 30 S30 Kl3 52 S3(EP3) 31 S31 Kl2 51 S2(EP2) 32 S32 , R4 C3 R3 GND CS CK DI DO KI1 KI2 KI3 KI4 KI5 R1, C1 : Constants should , : The constant should be set to match the panel, through testing or other means.