why the VTREG(Px) doesn't change responding to the relative register?

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Read-Only Author Liu Hui Posted 10-Mar-2003 07:21 GMT Toolset C51	why the VTREG(Px) doesn't change responding to the relative register? Liu Hui hello with the Keil uVISION2 51 simulation,sometimes,the register has been set,but the relative VTREG doesn't get to change .for example,in my programme,some positions of register P1 has been set 1,but PORT1 has nothing changed.In some particular programs,it gets to be worse. I wonder if it's a bug of the Keil simulative programme,and how can I make it work? Thanks and regards Huihl@netease.com

Read-Only Author Keil Support Intl. Posted 10-Mar-2003 12:51 GMT Toolset C51	RE: why the VTREG(Px) doesn't change responding to the relative register? Keil Support Intl. The simulator behaves exactly like an 8051 device. The PORTx VTREG represents the I/O pins whereas the symbol 'Px' (i.e. P1) is the SFR register itself. When you pull the PORTx value low (for example by modifing it in the peripheral dialogs), you cannot get it high by setting the SFR register. This is the same as with the chip (when you force a pin to low, you cannot get it high via the SFR register since it is then used as input). For more information refer to pages like: http://www.keil.com/dd/vtr/2976/1511.htm.

Read-Only Author Liu Hui Posted 11-Mar-2003 00:37 GMT Toolset C51	RE: why the VTREG(Px) doesn't change responding to the relative register? Liu Hui lots of thanks.I have gotten it with your help.