µVISION DEBUGGER: Port Lines Don't Toggle During Memory Access

Information in this article applies to:

• C51 Version 6.20 and later
• µVision Version 2.20 and later
• MCB520 Evaluation Board

QUESTION

I have a program that writes to external memory. I can view the values written in the memory window. The external bus interface of my device also toggles the I/O port pins. Is it possible to see also the toggles on the I/O ports when I use the dialog Peripherals - I/O Port?

ANSWER

No, the µVision simulator is not a cycle-based simulator and, therefore, it is not possible to see the memory access on the I/O Port lines.

To provide fast simulation speeds, µVision simulates a single instruction in one step. The behavior of on-chip peripherals and memory accesses is completely simulated at the logic level but not at the gate level. Therefore, you cannot see I/O port toggles of the peripherals or memory access. Instead, the logic behavior of the peripherals is reflected in virtual registers that are listed with the DIR VTREG command. This has the benefit that you can easily write debug functions that simulate complex peripherals.

MORE INFORMATION

• µVision Getting Started User's Guide, Chapter 5 and Chapter 6
• Application Note 147: CAN Simulation in µVision2
• Application Note 153: Using and Programming the I2C Bus

SEE ALSO

• µVision DEBUGGER: Using the PORTx VTREGs
• µVision DEBUGGER: I/O Pins don't toggle during Communication

Last Reviewed: Thursday, October 29, 2020