Component: Lookup tables (Storage)

Author	Matrix Ltd
Version	1.7
Category	Storage

Lookup tables component

A lookup-table component allowing an easy way to place arrays of static data into ROM memory. The LUT data is accessed directly allowing very low overhead when collecting the data.

Component Pack

FREE

Detailed description

No detailed description exists yet for this component

Examples

A look up table component is useful when including data into a program which may not be linear and therefore hard to calculate.

One example of this is a sine wave or working out a temperature based on the resistance of a thermistor.

For a simple example lets say we want to store a sine wave on board the microcontroller.

First of all we use Excel to generate the data for a sine wave to do this we work out the angles in degrees we want to reproduce, then convert the degrees to radians and then generate the Sine wave for the angle. the angle returned will be between -1 and 1 so we need to convert this to fit into the microcontroller's memory. The most efficient way is to store the value as a byte which means scaling up the output to 0 - 255 and removing the real portion of the number to give integer values.

File:SineWaveLUT.xlsx

Then using the file -> Save as menu in Excel we can export the data as a raw .CSV file.

File:SineWaveLUT.csv

The line in the CSV file we are interested in is the Integer Offset Data. We can then copy and paste this data into the integer property of the look up table component.

In this example Flowcode file we display the LUT data onto a graphical LCD display LUT Here is what you should expect to see on the glcd after running the simulation.

Downloadable macro reference

	GetFloats
Gets the float LUT
- FLOAT	Dest
- VOID	Return

	GenerateCache
Generates the C code for the arrays so it does not need to be done at compile time
- VOID	Return

	GetIntCount
Gets the number of int LUT entries
- UINT	Return

	ClearInts
Clear all int LUT values
- VOID	Return

	GetFloatCount
Gets the number of float LUT entries
- UINT	Return

	GetIntBits
Gets the number of bits-per-int in the LUT
- BYTE	Return

	SetIntBits
Sets the size of an int LUT entry
- BYTE	Bits
- VOID	Return

	GetFloatBits
Gets the number of bits-per-float in the LUT
- BYTE	Return

	ClearFloats
Clear all float LUT values
- VOID	Return

	GetFloat
Gets a float from the LUT
- ULONG	Index
- FLOAT	Return

	GetInts
Gets the int LUT
- ULONG	Dest
- VOID	Return

	GetLUTCount
Gets the number of individual data entries stored in the LUT.
- UINT	Return

	GetInt
Gets an integer from the LUT
- ULONG	Index
- ULONG	Return

	SetFloatBits
Sets the size of a float LUT entry
- BYTE	Bits
- VOID	Return

	AddInt
Int to add to the int array
- ULONG	Value
Int to add to the int array
- VOID	Return

	AddFloat
Add a float to the floating point LUT
- FLOAT	Value
Floating point values
- VOID	Return

Property reference

	Properties
	Storage Type
Controls the data type stored by the component.
	Storage Sign
Controls if the integer numbers are allowed to be negative. Unsigned = Numbers are positive only. Signed = Numbers can be positive and negative.
	Integers
Comma seperated integer data which is used to create the C code which is inserted into the ROM.
	Num Values
	Embed Into C
Flag to decide if code should be generated to C or not If this is false then the LUT is simulation only