HD64F3437TF16 Datasheet, PDF (182/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

7.12.3 Pin Functions in Each Mode
Port B has different pin functions in different modes. A separate description for each mode is
given below.
Pin Functions in Modes 1 and 2: In mode 1 (expanded mode with on-chip ROM disabled) and
mode 2 (expanded mode with on-chip ROM enabled), when the host interface enable bit (HIE) is
cleared to 0 in the system control register (SYSCR), port B is a general-purpose input/output port.
When the HIE bit is set to 1, selecting slave mode, port B becomes the host interface data bus
(XDB₇ to XDB₀). PBODR and PBDDR should be cleared to H'00 in slave mode. For details, see
section 14, Host Interface.
Figure 7.20 shows the pin functions in modes 1 and 2.
Port B
PB₇ (input/output)/XDB₇ (input/output)
PB₆ (input/output)/XDB₆ (input/output)
PB₅ (input/output)/XDB₅ (input/output)
PB₄ (input/output)/XDB₄ (input/output)
PB₃ (input/output)/XDB₃ (input/output)
PB₂ (input/output)/XDB₂ (input/output)
PB₁ (input/output)/XDB₁ (input/output)
PB₀ (input/output)/XDB₀ (input/output)
Figure 7.20 Pin Functions in Modes 1 and 2 (Port B)
153