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Peripheral Simulation

For Atmel AT91RM9200 — General Purpose I/O Ports (A-H)

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.

Port A (GPA) Dialog

Port A (GPA)

Port B (GPB) Dialog

Port B (GPB)

Port C (GPC) Dialog

Port C (GPC)

Port D (GPD) Dialog

Port D (GPD)

Port E (GPE) Dialog

Port E (GPE)

Port F (GPF) Dialog

Port F (GPF)

Port G (GPG) Dialog

Port G (GPG)

Port H (GPH) Dialog

Port H (GPH)

The GPx Dialog boxes allows you to configure the parallel I/O port using checkboxes. Controls in this dialog are presented in the following group.

GPx Group

  • The GPxCON buttons allow you to view or assign how each PIO pin will be used (e.g. Input, Output or nXDREQ1).
  • The GPxDAT check boxes show the current data contents of the PIO port.
  • The GPxUP check boxes enable or disable the internal pull-up resistor for the selected bit. Pull-up resisitors are enabled by default. Checking a box disables the pull-up resistor for that bit.
  • The PORTx check boxes reflect the data input to a port.

Data Type: unsigned long

The PORTx VTREGs represent the I/O pins of the simulated MCU for Port A, Port B, and so on. PORTA represents Port A, PORTB represents Port B, 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,


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


sets the upper four port pins of Port A to a value of 1 and all other 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:

PORTA |=  0x00000001;  /* Set PA0 Pin */
PORTB &= ~0x00000200;  /* Clr PB9 Pin */
PORTA ^=  0x00800000;  /* Toggle PA23 Pin */
Get more information about the
Peripheral Simulation Capabilities
of the µVision Debugger.
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