Assembly must be used to define the table because XC8 does not have any C language extension to declare constant data in code space as packed 14-bit words. I have tried a few other structures but cant seem to get the pic to echo back what i type into the terminal. These are a couple hundred bytes in machine code. You ask the question 'How to define 14-bit lookup table for PIC/XC8 (if its possible to do without assembly)' It is almost possible to do this in XC8 without assembly. I’m new to pics and am transitioning from Atmels to PIC’s I do know C and C++ but its a bit rusty any help would be great. Simply use some simple LZW or huffman (low dict size) compressor and decompressor. Especially since you're only planning to access the data sequentially, and since even of your 7 bits, 27 values don't occur and, probably, a few bit combos are way more likely than others: Note that PWM sequence does sound like you're trying to reproduce some band-limited signal. The C-Compiler we’ll be using is called XC8 from Microchip, for 8-Bit MCUs. Most of the advanced high-volume quality products are developed in C. That should both amount to roughly the same assembly, a few bytes in machine code. Using MPLAB X IDE, XC8 Compiler, and PICkit2 or 3. Or you just do a bit of pointer arithmetic: // get the 1000. elementĬase 0: value = table.word0 break Ĭase 1: value = table.word1 break Ĭase 7: value = table.word7 break PICmicro and assemble/compiler is being used the format, syntax and. The following descriptions indicate the distinctions within those device cores: The baseline core uses a 12-bit-wide instruction set and is available in PIC10, PIC12 and PIC16 part numbers. With the introduction of MPLAB X, configuration bits can no longer be set in the IDE. You can either just use pointers to your eight_words struct: // get the 1000. This guide describes the MPLAB XC8 C Compilers support for all 8-bit Microchip PIC devices with baseline, mid-range, enhanced mid-range and PIC18 cores.
Obviously, this won't work: static const uint8_t table = Īnd the _packed_ attribute will make any decent compiler actually emit structures of size 7 Bytes.Īccess then is super simple. Click the link to your target device and the page will show you the settings and values that are appropriate for your directives. Although normally described in a C language manual, the GNU C preprocessor.
The target PIC MCU is PIC16F1829 (8K words of program memory), and the compiler is XC8. These are located in the docs directory in the MPLAB XC8 C Compiler distribution that contains your PIC Assembler. 2.4.3 Accessing Structure Members 2.4.4 Bit Fields 2.4.5 Size of Structures. I'm writing the firmware for a simple testing device that would need to store a very large lookup table (I need 13500 entries with values 0.100 decimal).
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