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Hi I have the following array declared at the start of my program as global: int number[] = {0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x98}; 0 1 2 3 4 5 6 7 8 9 It is for a 7 segment display to display the numbers that I need, the array is from 0-9 in that order. My code to call the array is: P2 = number[4]; so in this case it should get the 4th number being 0x99 This works fine if i replace the 4 with 0,1 or 2 but anything greater than 2 all it does is return the data for 8 (80) If anyone can work out why this is doing this please let me know Thanks
"If I just change the definition to what you suggested should it work?" What you wrote originally should have worked, it just wasn't the most efficient use of resources on an 8051. If using Reinhard's code works you still have a problem you need to understand and fix. If you declare an array without specifying a memory space it will be created in the default memory space which will be either internal or external RAM. This is pointless as your array is read-only. Using the 'code' specifier causes the array to remain in code space. The other issue that was pointed out to you is the fact that you are storing 8 bit values in an array of 16 bit 'slots'. This is also wasteful. Reinhard is suggesting that you may have a hardware problem with the RAM which is causing your original declaration not to work properly. There are other possibilities though - what memory model are you using?
Hi my array is working correctly if it is declared as an integer in my program, however if I change it as suggested to unsigned char code then what happens is it only diplays for a very quick period of time <1 second then no longer displays. I have tried it in a simple program and it works fine however in my larger program this does not work. Can you suggest why this might be happening? Also I'm trying to display a 2 digit number 1 digit at a time so I'm using the following code: P2 = number[set_temp/10]; //Display Tens and P2 = number[set_temp%10]; //Display Units This also doesnt work properly, this time it wont work while trying to access the integer "set_temp" which is defined as: int set_temp = 27; however if I take out "set_temp" from the code above and replace it with 27 it works fine. This also works fine in the simple program however not in my larger program. If you would like to see my whole program code to work this out please email me on alex@allsound.com.au Thanks
What memory model are you using?
I'm not sure how do I tell?
It is a P89LPC935 PLCC version the numbers on the chip are: 89LPC935FA CD4397 TtG0440 A Alex
"I'm not sure how do I tell?" Project->Options for target. You really need to understand this stuff before you attempt to write code for the 8051.
"You really need to understand this stuff before you attempt to write code for the 8051." Absolutely! Standard advice: First, you need to read the uVision Getting Started guide, and work through the example projects in it. This will give you a proper introductions to the tools, how they work, and how to use them - rather than just jumping-in blindly at the deep-end! You need to read the following documents - commonly referred to as "the bible" for the 8051: Chapter 1 - 80C51 Family Architecture: http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_ARCH_1.pdf Chapter 2 - 80C51 Family Programmer's Guide and Instruction Set: http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_PROG_GUIDE_1.pdf Chapter 3 - 80C51 Family Hardware Description: http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_HARDWARE_1.pdf Are you also a newbie to 'C' programming in general? If so, you'll also need a good 'C' textbook. Here are some other introductory & reference materials: http://www.keil.com/books/8051books.asp http://www.8052.com/books.phtml http://www.8052.com/tutorial.phtml You will need to read the Data Sheet for your particular processor, and the Manual(s) for any development boards, etc. You will need to read the Manuals for the C51 Compiler, A51 Assembler, etc, etc,...
Thanks Guys for your advice, I'm in the process in reading the "bible", I have done some C programming previously, with a standard 8051 chip, I think I'm coming across problem as I have not used this compiler before and some of the syntax is different. I'm only a student however so I'm no expert when it comes to all this. I think using the P89LPC935 is also making it a little different as previously I didn't have all the extra features that it has so I'm new when it comes to programming these features. I would say my biggest problems lie in using the correct definitions/declarations and setup code for this chip/compiler. I have a fairly logical brain which helps when it come to the actual coding. Can any of you suggest why I get the 2 problems I talked about in the article I Posted 10/19/05 5:48:28. I think these are related to my setup/declarations. Thanks Again I appreciate your support Alex
You present only a code sniplet, but the problem might be somewhere else (i.e. variable definition, missing endless loop, ect.). I recommend that you single step through the program using the simulator. Reinhard
"I have not used this compiler before and some of the syntax is different." That's exactly why you should start by reading the Getting Started Guide - the clue is in the name! Read it, and work through the example projects in it.