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Declaring RAM areas for P89C668 (xdata problems)
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James Corbin Posted
6-Jul-2003 22:53 GMT Toolset
C51 |
 Declaring RAM areas for P89C668 (xdata problems)James Corbin
I believe I'm doing something incorrectly, probably relating to how I initialize and tell keil where RAM memory resides at.I'm using the latest version of uVision and C compiler. The P89C668 has 8k of onboard RAM. As I understand it, the P89C668 has the normal 256 bytes of 'internal' RAM and the rest is accessed as XDATA. So once setting Keil up, I edit the startup such as: IDATALEN EQU 100H XDATASTART EQU 101H XDATALEN EQU 2000H PDATASTART EQU 0H PDATALEN EQU 0H In the Options for Target, under the Target tab, I have the following settings: Use On-chip ROM (0-FFFF) - Checked Use On-chip XRAM (0-1EFF) - Checked Use multiple DPTR registers - Checked Nothing is in the Off-chip code or Xdata boxes and code banking is unchecked. Is this correct? My test setup consists of a Philips Mk2 emulator which has an 2x16 LCD attached. My LCD routines make use of a little RAM buffer declared like: unsigned char idata lcdbuf[2][16]; I have a function that first writes the contents of a passed buffer to lcdbuf and then displays whats in the buffer to the actual LCD:
WriteLCD("Hello Keil\n", LCD_LINE1);
WriteLCD("XDATA Prob\n", LCD_LINE2);
I run this on my emulator and it works perfectly everytime. Now, I change the data to xdata as follows: unsigned char xdata lcdbuf[2][16]; Now when I run the program on my emulator, I get all blanks on the LCD, as if the memory were not accessed correctly. Being that was the only thing changed, I'm convinced it's some RAM setting somewhere. Any ideas about what I could be doing incorrectly? Thanks James |
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James Corbin Posted
6-Jul-2003 23:01 GMT Toolset
C51 |
RE: Declaring RAM areas for P89C668 (xdata problems) James Corbin
BTW, it seems to simulate correctly (the reading\writing xdata part).
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James Corbin Posted
7-Jul-2003 02:20 GMT Toolset
C51 |
RE: Declaring RAM areas for P89C668 (xdata problems) James Corbin
http://www.keil.com/support/docs/1978.htmAnswered my own question. Thanks James |
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Vuppuladhadium Venkataramana Posted
1-Aug-2003 19:56 GMT Toolset
C51 |
RE: Declaring RAM areas for P89C668 (xdata problems) Vuppuladhadium Venkataramana
I guess you know the answer by now. I toostumbled upon this issue. All I had to do is to add one more line to startup.a51 code that was supplied by Keil. CSEG AT 0 ?C_STARTUP: LJMP STARTUP1 RSEG ?C_C51STARTUP STARTUP1: ; enable on-chip xdata RAM MOV AUXR1,#00H ; AUXR1/Bit 1 (clear to 0 to enable on-chip XRAM) This solved the problem. |
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