GCBASIC documentation
PROGMEM ( PFM )

Syntax:

        DATA DataSetName [as Byte | Word]
            // multiples values, strings etc.
            0,1,2,3
        END DATA

Command Availability:

Available on all PIC microcontrollers with DATA memory.

Explanation:

The DATA construct creates an DATA dataset for use with the specific microcontroller.  An DATA dataset is a list of values that are stored in the PROGMEM memory of the microcontroller, which then can be accessed using the ProgRead() command or other DATA read operations.

The advantage of an DATA dataset is that they are memory efficient being loaded directly into the DATA during programming operations.

DATA datasets are defined as follows:

Defining DATA datasets

Single data values

A single value on each line with in the dataset.  The example dataset, shown below, has the data on different line in within the set.

Simple example: This creates an DATA dataset at the first DATA location, then, the values of 12, 24, …​ 72 are the consecutive values.

        DATA EEDataSet as Byte
            12
            24
            36
            48
            60
            72
        End DATA

Multiple data values of the same line

The following example creates the DATA dataset at DATA offset address of 0x10.  

Multiple elements on a single line separated by commas.  The example dataset, shown below, has the data separated by , and on different line in within the dataset.

        DATA EEDataSource  as Byte
            12,  24, 36
            48,  60, 72
        End DATA

Data values as constants, and, with data transformation

Constants and calculations within the single line.   The example dataset, shown below, uses a defined constant to multiple the data with the dataset.

        #define calculation_constant 2

        DATA EEDataSource as Word
        1 * calculation_constant
        2 * calculation_constant
        3 * calculation_constant
        8 * calculation_constant
        4 * calculation_constant
        5 * calculation_constant
        End DATA

     

Data values as Strings

Strings can be defined.  Strings are delimited by double quotes.    The following examples show the methods.

Any ASCII characters between any two " " (double quotes) will be converted to dataset data.   Also see ASCII escape codes.

A source string can be one string per line or comma separated strings, therefore, on the same line.

Example:

    DATA Test_1 as Byte
     "ABCDEFGHIJ"
    End DATA

ASCII Escape code

Accepted escape strings are shown in the dataset below.

Complete working example program

This example creates several DATA datasets.  The example also create a lookup table.  The DATA dataset are addressed with the additional parameter to ensure there is no DATA dataset overlap.  

        #chip 16F886
        #option explicit

        #DEFINE USART_BAUD_RATE 9600
        #DEFINE USART_TX_BLOCKING
        #DEFINE USART_DELAY OFF

        Dim dataaddress, datavalue as Byte

        DATA DataSet1 as Byte
            3,2,1
        End DATA

        DATA VersionData as Byte
        "    PWM2Laser   "
        "  Fabrice ENGEL "
        "   Version 1.4  "
        "  November 2023 "
        End DATA

        For dataaddress = 0 to 2
            ProgramRead  ( @DataSet1 + dataaddress , datavalue )
            HserPrint datavalue
        Next

For more help, see ProgramRead, Creating DATA data from a Lookup Table