Analog-to-Digital Converter
Numerical Format
How do we Read the Result?
How do we Read the Result?
Integer format
Integer format
RESULTx
RESULTx
ACC
ACC
Data
Data
Mem
Mem
bit shift right
bit shift right
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
0
0
0
0
0
0
0
0
15
15
0
0
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
0
0
0
0
0
0
0
0
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
x
x
x
x
x
x
x
x
x
x
x
x
Example: read RESULT0 register
Example: read RESULT0 register
#include "DSP281x_Device.h"
void main(void)
{
Uint16 value;
// unsigned
value = AdcRegs.ADCRESULT0 >> 4;
}
#include "DSP281x_Device.h"
#include "DSP281x_Device.h"
void main(void)
void main(void)
{
{
Uint16 value;
Uint16 value;
// unsigned
// unsigned
value =
value =
AdcRegs
AdcRegs
.ADCRESULT0 >> 4;
.ADCRESULT0 >> 4;
}
}
What About Signed Input Voltages?
What About Signed Input Voltages?
Example:
Example:
-
-
1.5 V
1.5 V
≤
≤
V
V
in
in
≤
≤
+1.5 V
+1.5 V
1) Add 1.5 volts to analog input:
1) Add 1.5 volts to analog input:
V
V
in
in
1.5V
1.5V
Input
Input
Ch. x
Ch. x
V
V
DD
DD
GND
GND
V
V
DDA
DDA
ADCLO
ADCLO
-
-
+
+
R
R
R
R
R
R
-
-
+
+
R
R
R
R
C28x
C28x
#include "DSP281x_Device.h“
#define offset 0x07FF
void main(void)
{
int16 value;
// signed
value = (AdcRegs.ADCRESULT0 >> 4) – offset;
}
#include "DSP281x_Device.h“
#include "DSP281x_Device.h“
#define offset 0x07FF
#define offset 0x07FF
void main(void)
void main(void)
{
{
int16
int16
value;
value;
// signed
// signed
value = (
value = (
AdcRegs
AdcRegs
.ADCRESULT0 >> 4)
.ADCRESULT0 >> 4)
–
–
offset;
offset;
}
}
2) Subtract “1.5” from digital result:
2) Subtract “1.5” from digital result:
6 - 12
C28x - Analog-to-Digital Converter
Содержание C28 Series
Страница 64: ...Summary 3 16 C28x Peripheral Registers Header Files ...
Страница 78: ...Interrupt Sources 4 14 C28x Reset and Interrupts ...
Страница 218: ...Lab 9 DSP BIOS 9 22 C28x Using DSP BIOS ...
Страница 244: ...Lab 10 Programming the Flash 10 26 C28x System Design ...
Страница 273: ...Appendix A eZdsp F2812 C28x Appendix A eZdsp F2812 A 1 ...
Страница 275: ...Appendix eZdsp F2812 eZdsp F2812 Connector Header and Pin Diagram C28x Appendix A eZdsp F2812 A 3 ...
Страница 276: ...Appendix P2 Expansion Interface A 4 C28x Appendix A eZdsp F2812 ...
Страница 277: ...Appendix P4 P8 P7 I O Interface C28x Appendix A eZdsp F2812 A 5 ...
Страница 278: ...Appendix A 6 C28x Appendix A eZdsp F2812 ...
Страница 279: ...Appendix P5 P9 Analog Interface C28x Appendix A eZdsp F2812 A 7 ...
Страница 281: ...Appendix JP7 JP8 JP11 JP12 Boot Mode Select JP9 PLL Disable DS1 DS2 LEDs C28x Appendix A eZdsp F2812 A 9 ...
Страница 282: ...Appendix A 10 C28x Appendix A eZdsp F2812 TP1 TP2 Test Points ...
