Pull-Up Control - Epson S1C17001 Technical Manual

10 INPUT/OUTPUT PORT (P)

10.4 Pull-up Control

The input/output port contains a pull-up resistor, which you can choose to use or not use individually for each bit
using the PxPU[7:0] (Px_PU register).
∗ P0PU[7:0]: P0[7:0] Port Pull-up Enable Bits in the P0 Port Pull-up Control (P0_PU) Register (D[7:0]/0x5203)
∗ P1PU[7:0]: P1[7:0] Port Pull-up Enable Bits in the P1 Port Pull-up Control (P1_PU) Register (D[7:0]/0x5213)
∗ P2PU[7:0]: P2[7:0] Port Pull-up Enable Bits in the P2 Port Pull-up Control (P2_PU) Register (D[7:0]/0x5223)
∗ P3PU[3:0]: P3[3:0] Port Pull-up Enable Bits in the P3 Port Pull-up Control (P3_PU) Register (D[3:0]/0x5233)
Setting PxPU[7:0] to 1 (default) enables the pull-up resistor and pulls up the port pin in input mode. It will not be
pulled up if set to 0.
The PxPU[7:0] setting is disabled in output mode, and the pin is not pulled up.
Input/output ports that are not used should be set with pull-up enabled.
This pull-up setting is also enabled for ports for which the peripheral module function has been selected.
A delay will occur in the waveform rise-up depending on time constants such as pull-up resistance and pin load
capacitance if the port pin is switched from Low level to High level by the internal pull-up resistor. An appropriate
wait time must be set for the input/output port loading. The wait time set should be a value not less than that calcu-
lated from the following equation.
Wait time = R x (C + load capacitance on board) x 1.6 [s]
IN IN
R : pull-up resistance maximum value
IN
C : pin capacitance maximum value
IN
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EPSON
S1C17001 TECHNICAL MANUAL