Enhanced Queued Analog-to-Digital Converter (EQADC)
27-100
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
27.7.6.6.2
MAC Unit and Operand Data Format
The MAC unit diagram is shown in
. Each on-chip ADC has a separate MAC unit to fine-tune
its conversion results. The description below considers the general calibration constant registers but it is
the same for the alternate calibration constants.
The OCC0/1 operand is a 14-bit signed value stored in the
Section 27.6.3.5, ADC0/1 Offset Calibration
Constant Registers (ADC0_OCCR and ADC1_OCCR)
. The RAW_RES operand is the raw uncalibrated
result, and it is the direct output from the on-chip ADCs but passing through the resolution adjustment
block. The GCC0/1 operand is a 15-bit fixed point unsigned value stored in the
Gain Calibration Constant Registers (ADC0_GCCR and ADC1_GCCR)
GCC_INT.GCC_FRAC
binary format. The integer part of the GCC (GCC_INT=GCC[1]) contains a single
binary digit while its fractional part (GCC_FRAC=GCC[2:15]) contains 14 bits - see
. The
gain constant equivalent decimal value ranges from 0 to 1.999938..., as shown in
. Two is
always added to the MAC output - see
Section 27.8.6.3, Quantization Error Reduction During Calibration
.
CAL_RES output is the calibrated result, and it is a 14-bit unsigned value. CAL_RES is truncated to
0x3FFF, in case of a overflow, and to 0x0000, in case of an underflow.
Figure 27-63. MAC Unit Diagram
GCC_INT - Integer part of the gain calibration constant for ADC0/1
GCC_INT is the integer part of the gain calibration constant for ADC0/1.
GCC_FRAC[1:14] - Fractional part of the gain calibration constant for ADC0/1
GCC_FRAC is the fractional part of the gain calibration constant for ADC0/1. GCC_FRAC can
expresses decimal values ranging from 0 to 0.999938...
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
GCC_INT
GCC_FRAC
GCC[1]
GCC[2:15]
Figure 27-64. Gain Calibration Constant Format
MAC Unit
Calibrated Result (CAL_RES)
(14-bit unsigned value)
Raw Uncalibrated Result
(RAW_RES)
(12-bit unsigned value)
Gain Calibration Constant (GCC0/1)
(15-bit fixed point unsigned value
from ADC0/1_GCCR register)
Offset Calibration Constant (OCC0/1)
(14-bit signed value
from ADC0/1_OCCR register)
+
2
Summary of Contents for PXR4030
Page 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
Page 30: ...PXR40 Microcontroller Reference Manual Rev 1 Freescale Semiconductor xxx...
Page 40: ...PXR40 Microcontroller Reference Manual Rev 1 xl Freescale Semiconductor...
Page 66: ...Memory Map PXR40 Microcontroller Reference Manual Rev 1 2 4 Freescale Semiconductor...
Page 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
Page 1168: ...Decimation Filter 28 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...