Hi all,

I am developing a USB Device with TIs TUSB3200. The TUSB3200 is connectet to P0 (AD0..AD7) and P2(A8 .. A10) and ALE. of a AT89C55. TUSB3200 is mapped to XMEM and it is accessed at 0xF800 to 0xFFFF with MOVX A,@DPTR. It is the only device on the AD bus. Code comes from build in Flash Mem. (EA=1). I don't want to use MOVX A,@Ri and control P2 seperately since then I have to rewrite a large amount of code.
Now I want to use P2.4 .. P2.7 as additional input pins.
I know that P2 is overwriten when I am doing a XMEM Write, but since I am using only XMEM above 0xF800 the pins should remain at high level and it should be possible to read the P2. Additionally I can set P2 to 0xFF before reading the port.
Does somebody know if this will work ?

Cheers
Thomas