Chapter 3 Port Functions
51
P21Figure 3-3-5 Configuration and Functions of P21
Data bus
R
D
L
Q
Reset
Read Read
Read
Schmitt trigger input
R
D
L
Q
Reset
Read Read
Pull-up resistor control
Port input data
Special function input data
Special function input data
AC zero-cross detection circuit
P2PLU1
P2IN1
P21IM
P2PLU
(x'03F42')
P2IN
(x'03F22')
FLOAT1
(x'03F4B')
SENS
Pull-up
resistor
control
Port input
Control bit
Register
(address)
Control bit
Register
(address)
Register
(address)
Special
function
input
selection
Special function
Control bit
P21
I/O Port Configuration and Functions