
Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5566 Microcontroller Reference Manual, Rev. 2
19-118
Freescale Semiconductor
5. Write the GCC value to ADCn gain calibration registers (see Section
Gain Calibration Constant Registers (ADC0_GCCR and ADC1_GCCR)
ADCn offset calibration constant registers (see Section
Section 19.3.3.5, “ADCn Offset
Calibration Constant Registers (ADC0_OCCR and ADC1_OCCR)
”) using write configuration
commands.
19.5.6.2
Example Calculation of Calibration Constants
The raw results obtained when sampling reference voltages 25% V
REF
and 75% V
REF
were, respectively,
3798 and 11592. The results that should have been obtained from the conversion of these reference
voltages are, respectively, 4096 and 12288. Therefore, using
, the gain
and offset calibration constants are:
GCC=(12288-4096)
÷
(11592-3798) = 1.05106492-> 1.05102539
1
= 0x4344
OCC=12288-1.05106492*11592 -2 = 102.06-> 102 = 0x0066
shows, for this particular case, examples of how the result values change according to GCC
and OCC when result calibration is executed (CAL=1) and when it is not (CAL=0).
19.5.6.3
Quantization Error Reduction During Calibration
shows how the ADC transfer curve changes due to the addition of two to the MAC output
during the calibration. See MAC output equation in
Section 19.4.5.4, “ADC Calibration Feature
.”
The
maximum absolute quantization error is reduced by half leading to an increase in accuracy.
1. This calculation is rounded down due to binary approximation.
Table 19-58. Calibration Example
Input Voltage
Raw result (CAL=0)
Calibrated result (CAL=1)
Hexadecimal
Decimal
Hexadecimal
Decimal
25% VREF
0x0ED6
3798
0x1000
4095.794
75% VREF
0x2D48
11592
0x3000
12287.486
Содержание MPC5566
Страница 12: ...MPC5566 Microcontroller Reference Manual Devices Supported MPC5566 MPC5566 RM Rev 2 0 23 Apr 2008...
Страница 81: ...Introduction MPC5566 Microcontroller Reference Manual Rev 2 1 24 Freescale Semiconductor...
Страница 135: ...Signal Description MPC5566 Microcontroller Reference Manual Rev 2 2 54 Freescale Semiconductor...
Страница 189: ...Reset MPC5566 Microcontroller Reference Manual Rev 2 4 20 Freescale Semiconductor...
Страница 331: ...System Integration Unit SIU MPC5566 Microcontroller Reference Manual Rev 2 6 128 Freescale Semiconductor...
Страница 343: ...Crossbar Switch XBAR MPC5566 Microcontroller Reference Manual Rev 2 7 12 Freescale Semiconductor...
Страница 361: ...Error Correction Status Module ECSM MPC5566 Microcontroller Reference Manual Rev 2 8 18 Freescale Semiconductor...
Страница 455: ...Interrupt Controller INTC MPC5566 Microcontroller Reference Manual Rev 2 10 42 Freescale Semiconductor...
Страница 603: ...Flash Memory MPC5566 Microcontroller Reference Manual Rev 2 13 38 Freescale Semiconductor...
Страница 609: ...SRAM MPC5566 Microcontroller Reference Manual Rev 2 14 6 Freescale Semiconductor...
Страница 679: ...Boot Assist Module BAM MPC5566 Microcontroller Reference Manual Rev 2 16 20 Freescale Semiconductor...
Страница 997: ...Deserial Serial Peripheral Interface DSPI MPC5566 Microcontroller Reference Manual Rev 2 20 72 Freescale Semiconductor...
Страница 1037: ...Enhanced Serial Communication Interface eSCI MPC5566 Microcontroller Reference Manual Rev 2 21 40 Freescale Semiconductor...
Страница 1073: ...MPC5566 Microcontroller Reference Manual Rev 2 22 36 Freescale Semiconductor...
Страница 1081: ...Voltage Regulator Controller VRC and POR Module MPC5566 Microcontroller Reference Manual Rev 2 23 8 Freescale Semiconductor...
Страница 1093: ...IEEE 1149 1 Test Access Port Controller JTAGC MPC5566 Microcontroller Reference Manual Rev 2 24 12 Freescale Semiconductor...
Страница 1185: ...Nexus MPC5566 Microcontroller Reference Manual Rev 2 25 92 Freescale Semiconductor...
Страница 1267: ...MPC5566 Reference Manual Revision History MPC5566 Microcontroller Reference Manual Rev 2 Freescale Semiconductor C 10...
Страница 1268: ...MPC5566 Reference Manual Revision History MPC5566 Microcontroller Reference Manual Rev 2 Freescale Semiconductor C 11...