PXD10RM Datasheet, PDF (125/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

5.3 Functional description
5.3.1 Analog channel conversion
Two conversion modes are available within the ADCDig:
• Normal conversion
• Injected conversion
5.3.1.1 Normal conversion
This is the normal conversion that the user programs by configuring the normal conversion mask registers
(NCMR). Each channel can be individually enabled by setting ‘1’ in the corresponding field of NCMR
registers. Mask registers must be programmed before starting the conversion and cannot be changed until
the conversion of all the selected channels ends (NSTART bit in the Main Status Register (MSR) is reset).
5.3.1.2 Start of normal conversion
By programming the configuration bits in the Main Configuration Register (MCR), the normal conversion
can be started in two ways:
• By software (TRGEN reset)—If the external trigger enable bit is reset, the conversion chain starts
when the NSTART bit in the MCR is set.
• By trigger (TRGEN set)—An on-chip internal signal triggers an ADC conversion. The settings in
the MCR select how conversions are triggered based on these internal signals:
— If the EDGLEV (edge/level selection) bit in the MCR is cleared, then Aa rising/falling edge
(depending on the EDGE bit in MCR) detected in the signal sets the NSTART bit in the MSR
and starts the programmed conversion. EDGE = 0 selects a falling edge. EDGE = 1 selects a
rising edge.
— If the EDGLEV bit in the MCR is set, Tthe conversion is started if and only if the NSTART bit
in the MCR is set and the programmed level on the trigger signal is detected. The level is
selected using the EDGE bit in the MCR. EDGE = 0 means that the start of conversion is
enabled if the signal is low. If EDGE = 1, the start of conversion is enabled when the signal is
high.
PXD10 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
5-3
Preliminary—Subject to Change Without Notice