ISD94100 Series Technical Reference Manual
Sep 9, 2019
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6.5.5
Functional Description
6.5.5.1
Input Mode
Writing 0b00 into MODEn bits (Px_MODE[2n+1:2n]) puts the corresponding Px.n pin in Input mode,
and the pin will be in tri-state (high impedance). The input pin’s status is reflected in PX PIN[n] bit.
For example if PA.0 is an input pin, the input level can be read by reading PA_PIN register, and
PA_PIN[0] has the input value for PA.0 pin.
6.5.5.2
Push-pull Output Mode
Writing 0b01 into MODEn bits (Px_MODE[2n+1:2n]) puts the corresponding Px.n pin in in Push-
pull Output mode, and the pin supports digital output function with source/sink current capability.
As shown in Figure 6.5-2, the bit value in the corresponding DOUT (Px_DOUT[n]) is driven on the
pin.
Port Pin
Port Pin
N
N
P
P
VDD
VDD
Port Latch Data
Port Latch Data
Input Data
Input Data
Figure 6.5-2 Push-Pull Output
6.5.5.3
Open-drain Mode
Writing 0b10 to MODEn bits (Px_MODE[2n+1:2n]) configures the corresponding Px.n pin as Open-
drain mode I/O pin. External pull-up register is required to drive high state. If DOUT (Px_DOUT[n])
bit is 0, the pin drives low. If DOUT (Px_DOUT[n]) bit is 1, the pin drives high assuming there is
external pull high.
Open-drain Mode I/O function is shown in Figure 6.5-3.
Port Pin
Port Pin
N
N
Port Latch Data
Port Latch Data
Input Data
Input Data
