MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor
19-87
19.4.5.3
Time Stamp Feature
The on-chip ADCs can provide a time stamp for the conversions they execute. A time stamp is the value
of the time base counter latched when the eQADC detects the end of the analog input voltage sampling. A
time stamp for a conversion command is requested by setting the TSR bit in the corresponding command.
When TSR is negated, that is a time stamp is not requested, the ADC returns a single result message
containing the conversion result. When TSR is asserted, that is a time stamp is requested, the ADC returns
two result messages; one containing the conversion result, and another containing the time stamp for that
conversion. The result messages are sent in this order to the RFIFOs and both messages are sent to the
same RFIFO as specified in the MESSAGE_TAG field of the executed conversion command.
The time base counter is a 16-bit up counter and wraps after reaching 0xFFFF. It is disabled after reset and
it is enabled according to the setting of ADC_TSCR[TBC_CLK_PS] field (see Section 19.3.3.2).
TBC_CLK_PS defines if the counter is enabled or disabled, and, if enabled, at what frequency it is
incremented. The time stamps are returned regardless of whether the time base counter is enabled or
disabled. The time base counter can be reset by writing 0x0000 to the ADC_TBCR (Section 19.3.3.3) with
a write configuration command.
19.4.5.4
ADC Calibration Feature
19.4.5.4.1
Calibration Overview
The eQADC provides a calibration scheme to remove the effects of gain and offset errors from the results
generated by the on-chip ADCs. Only results generated by the on-chip ADCs are calibrated. The results
generated by ADCs on the external device are directly sent to RFIFOs unchanged. The main component
of calibration hardware is a multiply-and-accumulate (MAC) unit, one per on-chip ADC, that is used to
calculate the following transfer function which relates a calibrated result to a raw, uncalibrated one.
CAL_RES = GCC * R OCC + 2;
where:
•
CAL_RES is the calibrated result corresponding the input voltage V
i
.
•
GCC is the gain calibration constant.
•
RAW_RES is the raw, uncalibrated result corresponding to an specific input voltage V
i
.
•
OCC is the offset calibration constant.
•
The addition of two reduces the maximum quantization error of the ADC. See
“Quantization Error Reduction During Calibration
0b11101
60
2.0 133
125
0b11110
62
1.94 129
121
0b11111
64
1.88 125
117
Table 19-47. ADC Clock Configuration Example (Continued)
(System Clock Frequency = 120 MHz)
ADC0/1_CLK_PS[0:4]
System Clock
Divide Factor
ADC Clock in MHz
(System Clock =
120MHz)
Differential Conversion
Speed with Default
Sampling Time
(13 + 2 cycles) in
ksamp/s
Single-Ended
Conversion Speed with
Default Sampling Time
(14 + 2 cycles) in
ksamp/s
Summary of Contents for MPC5553
Page 5: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 2 Freescale Semiconductor...
Page 21: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 xvi Freescale Semiconductor...
Page 47: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 1 26 Freescale Semiconductor...
Page 163: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 4 20 Freescale Semiconductor...
Page 179: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 5 16 Freescale Semiconductor...
Page 561: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 13 38 Freescale Semiconductor...
Page 615: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 14 54 Freescale Semiconductor...
Page 707: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 17 68 Freescale Semiconductor...
Page 755: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 18 48 Freescale Semiconductor...
Page 873: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 19 118 Freescale Semiconductor...
Page 984: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 Freescale Semiconductor 21 41...
Page 985: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 21 42 Freescale Semiconductor...
Page 1019: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 22 34 Freescale Semiconductor...
Page 1129: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 25 90 Freescale Semiconductor...
