Hello. I am working with some existing code that we previously used SDCC as the compiler for the Nordic Semiconductor nRF24E1. I am porting this code over to the Keil compiler and I am having some problems. With the SDCC compiler it appeared that we were running out of RAM before so we were using part of the program space as RAM. I was assuming we were doing this using the XDATA command. I could compile the code using the XDATA type on the variable that I needed to place in Program memory space. When using the SDCC compiler, the variable that was being placed in program memory space was being specified to be in a specific memory location. I am was not explicitly picking a location for the variable using Keil. When using the Keil compiler, the code will compile but when I call a function that would use the variable that would be in XDATA, the device responds in a weird manner. Is there a way to explicitly say place the XDATA here and then when I use XDATA it will work properly? Is there any documentation on using the XDATA to store variables or any examples that I could view?
My code will compile and when it does I get the following info: linking... Program Size: data=231.0 xdata=0 code=2885 To get this to compile I had to reduce the size of one of the variables (an array, reduced from 15 bytes to 8) so that the code would compile. I kept receiving data overflow errors with the array being a larger size. My question is: Looking at the above program size it states data = 231 and looking at the datasheet it states the nRF24E1 has 256 bytes of RAM. Why is it that I cannot use the entire contents of RAM? I could make use of the extra RAM if there is any available. Can you please let me know? In Keil, I am using the small memory model: variables in Data, code rom size: compact 2K functions, and no operating system.
Here is the information about my version of the Keil Compiler.
IDE-Version: µVision3 V3.72 Copyright (c) Keil Elektronik GmbH / Keil Software, Inc. 1995 - 2008
Tool Version Numbers: Toolchain: C51 Compiler/Assembler Kit Version: 8.17 Toolchain Path: C:\Keil\C51\BIN\ C Compiler: C51.Exe V8.17 Assembler: A51.Exe V8.01 Linker/Locator: BL51.Exe V6.15 Librarian: LIB51.Exe V4.24 Hex Converter: OH51.Exe V2.6 CPU DLL: S8051.DLL V3.64 Dialog DLL: DP51.DLL V2.53
Thanks for the help.
Josh
You may have 256 bytes of RAM, but if you are going to fit a stack there too, you must leave a suitable number of bytes for the stack.
If the chip has any XDATA memory, then you should configure your project to know about this memory. And then tag some variables as xdata.