Hi, I am using the Keil uVision 2 software to develop a firmware driver. I have one technical related to the sbit definitions. Lets say i have couple of sbit definitions as follows: sbit JTAG_TDO = 0xB0+0; sbit ALT_JTAG_TDO = 0x80+0; In the course of program execution, based on some condition I want JTAG_TDO point to the ALT_JTAG_TDO pin so that whatever i write to JTAG_TDO gets written to ALT_JTAG_TDO at the port address 0x80+0 instead of the original 0xB0+0. I tried doing &JTAG_TDO = &ALT_JTAG_TDO and that raised a compiled error. Please let me know how to dynamically change the port pin addressing?
Our application now takes about 5 sec to initialize and the customers are complaining already Just stencil "Microsoft Windows" on the box and they will think it is fast :) Please throw some other alternatives? . Please... redo the hardware to change the pins (so that alternate pins are on same port and such), then you can do things like this: instead of sbit p0.0 alternating with sbit p0.1 you can do P0 |= raplph; where ralph can be set to 1 or 2 for the alternation.. Erik
To dredge up an ancient forgotten evil: self-modifying code. If you have von Neumann memory (that is, you can write to your program store), and know the address of the instruction that accesses the pin, you can overwrite the byte that contains the bit address so that the instruction fetches from different bits. If you do such a thing, I'd recommend writing the fetching routine in assembly so that you can exactly control the instruction sequence. You'll also need giant screaming comments that the source you see is not the code that actually gets run, with a reference to place that changes it.
ah .... one other possibility put the whole kit and kaboodle into a aubroutine using pin a. Then make a copy, rename it and change globally pin a to pin b. then it is a simple matter of if (ralph) { funca(); } else { funcb(): } Erik
My funca() is huge and making a copy to create funcb() may not fit in the internal RAM as I think it has only 8K bytes of space.
RAM??? what are you talking about, in a '51 the code is in ROM/PROM?Flash. Erik
If you mistyped and mean ROM, get a device with more, stepping up from e.g. 8k to 16 k will cost you only pennies. Erik