11
11-34
A-D Converters
32180 Group User's Manual (Rev.1.0)
11.3.2 A-D Conversion by Successive Approximation Method
The A-D Converters use an A-D conversion start trigger (software or hardware) as they start A-D conversion.
Once A-D conversion begins, the following operation is automatically performed.
1. During single mode, A-D Single Mode Register 0’s A-D conversion/comparate completion bit is cleared to "0".
During scan mode, A-D Scan Mode Register 0’s A-D conversion completion bit is cleared to "0".
2. The content of the A-D Successive Approximation Register is cleared to H’0000.
3. The A-D Successive Approximation Register’s most significant bit (bit 6) is set to "1".
4. The comparison voltage, Vref (Note 1), is fed from the D-A Converter into the comparator.
5. The comparison voltage, Vref, and the analog input voltage, VIN, are compared, with the comparison result
stored in bit 6.
If Vref < VIN, then bit 6 = "1"
If Vref > VIN, then bit 6 = "0"
6. Operations in 3 through 5 above are executed for all other bits from bit 7 to bit 15.
7. The value stored in the A-D Successive Approximation Register by the time comparison for bit 15 has finished
is held in it as the A-D conversion result.
11.3 Functional Description of A-D Converters
1st comparison
b6
7
8
9
10
11
12
13
14
b15
1
0
0
0
0
0
0
0
0
0
n9
1
0
0
0
0
0
0
0
0
n9
n8
1
0
0
0
0
0
0
0
n9
n8
n7
n6
n5
n4
n3
n2
n1
1
2nd comparison
3rd comparison
10th comparison
Conversion
completed
n9
n8
n7
n6
n5
n4
n3
n2
n1
n0
Result of 1st comparison
Result of 2nd comparison
If Vref > VIN, then nX = 0
If Vref < VIN, then nX = 1
A-D Successive Approximation Register (ADiSAR)
i = 0, 1
Figure 11.3.2 Changes of the A-D Successive Approximation Register during A-D Convert Operation
Note 1: The comparison voltage, Vref (the voltage fed from the D-A Converter into the comparator), is
determined according to changes of the A-D Successive Approximation Register content. Shown
below are the equations used to calculate the comparison voltage, Vref.
• If the A-D Successive Approximation Register content = 0
Vref [V] = 0
• If the A-D Successive Approximation Register content = 1 to 1,023
Vref [V] = (reference voltage VREF / 1,024)
×
(A-D Successive Approximation Register content – 0.5)
Содержание M32R/ECU Series
Страница 17: ...12 This page is blank for reasons of layout...
Страница 18: ...CHAPTER 1 OVERVIEW 1 1 Outline of the 32180 Group 1 2 Block Diagram 1 3 Pin Functions 1 4 Pin Assignments...
Страница 712: ...CHAPTER 18 OSCILLATOR CIRCUIT 18 1 Oscillator Circuit 18 2 Clock Generator Circuit...
Страница 794: ...CHAPTER 22 TYPICAL CHARACTERISTICS...
Страница 795: ...22 22 2 32180 Group User s Manual Rev 1 0 TYPICAL CHARACTERISTICS To be written at a later time...
Страница 796: ...APPENDIX 1 MECHANICAL SPECIFICAITONS Appendix 1 1 Dimensional Outline Drawing...
Страница 798: ...APPENDIX 2 INSTRUCTION PROCESSING TIME Appendix 2 1 32180 Instruction Processing Time...
Страница 802: ...APPENDIX 3 PROCESSING OF UNUSED PINS Appendix 3 1 Example Processing of Unused Pins...