Peripheral Simulation

For NXP (founded by Philips) 83/87C554 — Port 4 (Pseudo bidirectional, Push-Pull, High Impedance, Open Drain)

Simulation support for this peripheral or feature is comprised of:

• Dialog boxes which display and allow you to change peripheral configuration.
• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

Parallel Port 4 Dialog

This dialog displays the SFR and pins of Port 4.

• P4: This is the P4 SFR. The HEX value and value of each bit is displayed and may be changed from this dialog.
• Pins: These are the states of the pins on the simulated MCU. When used as outputs, these have the same value as the P4 SFR. When used as inputs (P4.x is 1) you may set the level of the input pin to high (1) or low (0).

PORTx VTREG
Data Type: unsigned char

The PORTx VTREGs represent the I/O pins of the simulated MCU for Port 0, Port 1, and so on. PORT0 represents Port 0, PORT1 represents Port 1, etc. You may read PORTx to determine the state of the output pins of that port. For example, in the command window, you may type,

PORT0

to obtain value corresponding to the set pins of Port 0. You may also change the input values of port pins by changing the value of the VTREG. For example,

PORT1=0xF0

sets the upper four port pins of Port 1 to a value of 1 and the lower 4 port pins to a value of 0. You may use the bitwise operators AND(&), OR(|) and XOR(^) to change individual bits of the PORTx VTREGs. For example:

PORT1 |=  0x01;  /* Set P1.0 Pin */
PORT3 &= ~0x02;  /* Clr P3.1 Pin */
PORT1 ^=  0x80;  /* Toggle P1.7 Pin */