Enhanced Queued Analog-to-Digital Converter (EQADC)
27-44
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
Table 27-21. EQADC_CFxRw Field Descriptions
Field
Description
0
ADC0/1_EN
Enable bit for ADC0/1. ADC0/1_EN enables ADC0/1 to perform A/D conversions. Refer to
Section 27.7.6.1, Enabling and Disabling the On-chip ADCs
, for details.
0 ADC is disabled. Clock supply to ADC0/1 is stopped.
1 ADC is enabled and ready to perform A/D conversions.
Note: The bias generator circuit inside the ADC hard macro ceases functioning when both ADC0_EN and
ADC1_EN bits are negated.
Note: Conversion commands sent to the CBuffer of a disabled ADC are ignored by the ADC control
hardware.
Note: When the ADC0/1_EN status is changed from asserted to negated, the ADC Clock will not stop until
it reaches its low phase.
1–3
Reserved
4
ADC0/1_EMUX
External Multiplexer enable for ADC0/1. When ADC0/1_EMUX is asserted, the MA pins will output digital
values according to the number of the external channel being converted for selecting external multiplexer
inputs. Refer to
Section 27.7.7, Internal/External Multiplexing
, for a detailed description about how
ADC0/1_EMUX affects channel number decoding.
0 External multiplexer disabled; no external multiplexer channels can be selected.
1 External multiplexer enabled; external multiplexer channels can be selected.
Note: Both ADC0 and ADC1 of an eQADC module pair must be enabled before calibrating or using either
ADC0 or ADC1 of the pair. Failure to enable both ADC0 and ADC1 of the pair can result in inaccurate
conversions.
Note: Both ADC0/1_EMUX bits must not be asserted at the same time.
Note: The ADC0/1_EMUX bit must only be written when the ADC0/1_EN bit is negated. ADC0/1_EMUX
can be set during the same write cycle used to set ADC0/1_EN.
5–9
Reserved
10
ADC0/1_CLK_SEL
Clock Selector for ADC0/1. The ADC0/1_CLK_SEL is used to select between the platform clock signal or
the prescaler output signal. The prescaler provides the platform clock signal divided by a even factor from
2 to 64. This is required to permit the ADC to run as fast as possible when the device is in Low Power Active
mode and platform clock is around 1 MHz.
0 Prescaler output clock is selected.
1 Platform clock is selected - maximum frequency.
Note: The ADC0/1_CLK_SEL bits must only be written when the ADC0/1_EN bit is negated.
ADC0/1_CLK_SEL can be set during the same write cycle used to set ADC0/1_EN.
11–15
ADC0/1_CLK_PS
Clock Prescaler Field for ADC0/1. The ADC0/1_CLK_PS field controls the platform clock divide factor for
the ADC0/1 clock as in
Section 27.7.6.2, ADC Clock and Conversion Speed,
for details
about how to set ADC0/1_CLK_PS.
Note: The ADC0/1_CLK_PS field must only be written when the ADC0/1_EN bit is negated. This field can
be configured during the same write cycle used to set ADC0/1_EN.
Summary of Contents for PXR4030
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