AN123

Rev. 1.1

5

Software Example

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// DAC1_fgen1.c

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//

// AUTH: BW,FB

// DATE: 2 OCT 01

//

// Target: C8051F02x

// Tool chain: KEIL C51

//

// Description:

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Example source code which outputs waveforms on DAC1.

DAC1’s output is

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scheduled to update at a rate determined by the constant

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<SAMPLE_RATE_DAC>, managed and timed by Timer4.

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Implements a 256-entry full-cycle sine table of 16-bit precision. Other

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waveforms supported are square, triangle, and saw tooth.

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The output frequency is determined by a 16-bit phase adder.

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At each DAC update cycle, the phase adder value is added to a running

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phase accumulator, <phase_accumulator>, the upper bits of which are used

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to access the sine lookup table.

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The program is controlled through UART using HyperTerminal running on a

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PC. All commands are two characters in length and have optional

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frequency and amplitude arguments. Note that the amplitude parameter

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cannot be specified unless the frequency is also specified.

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Command Format:

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XX [frequency] [amplitude]

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where XX denotes the command

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Command List:

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SQ - Square Wave

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SI - Sine Wave

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TR - Triangle Wave

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SA - Saw Tooth Wave

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OF - Output OFF

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?? - Help

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// Includes

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#include <c8051f020.h>

// SFR declarations

#include <stdio.h>

#include <string.h>

#include <ctype.h>

#include <stdlib.h>

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// 16-bit SFR Definitions for ‘F02x

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