Freescale Semiconductor ColdFire MCF52210 - Manual (Page 466)

Analog-to-Digital Converter (ADC)
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
26-30 Freescale Semiconductor
completion of the previous scan. In loop parallel scan modes, both converters restart together if
SIMULT equals 1 and restart independently if SIMULT equals 0. All subsequent start and sync pulses are
ignored after the scan begins. Scanning can only be terminated by setting a STOPn bit. Use STOP0 in the
CTRL1 register if operating in a sequential or simultaneous parallel mode. If operating in a
non-simultaneous parallel mode, use STOP0 to stop converter A and STOP1 in the CTRL2 register to stop
converter B.
26.5.6 Scan Configuration and Control
The operation of the ADC module is controlled by the CTRL1 and CTRL2 registers. The CTRL1 register
is described in
Section 26.4.1, “Control 1 Register (CTRL1) ”. The structure of the CTRL2 register
depends on whether the ADC is in sequential-scan or parallel-scan mode (see Section 26.4.2.1, “CTRL2
Under Sequential Scan Modes ” and Section 26.4.2.2, “CTRL2 Under Parallel Scan Modes ”, respectively).
These are used to set the scan mode, configure channels, and start/stop scans.
The ADC can operate in several sequential or parallel scan modes, as determined by CTRL1[SMODE].
These are summarized in
Table 26-21 . When the ADC operates in a parallel scan mode, its functionality
can be further controlled by CTRL2[SIMULT].
All scan modes make use of the 8 sample slots defined by the ADLST1 and ADLST2 registers. A scan is
the process of stepping through these sample slots, converting the analog input indicated by that slot, and
storing the result. Slots that are not required may be disabled by writing 1 to the appropriate bits of the
SDIS register.
Input pairs AN0-1, AN2-3, AN4-5, and AN6-7 may be configured as differential pairs using
CTRL1[CHNCFG]. When a slot in ADLSTn refers to either member of a differential pair, a differential
measurement on that pair is made; otherwise, a single-ended measurement is taken on that input. The
details of single-ended and differential measurements are described in
Section 26.5.2.1, “Single-Ended
Samples ” and Section 26.5.2.2, “Differential Samples ”, respectively.
CTRL1[SMODE] determines whether the slots are used to perform a sequential scan of up to 8 samples
or 2 parallel scans up to 4 samples. It also controls how these scans are initiated/terminated and whether
the scans are performed one time or repetitively. For more details, please see
Figure 26-18 and
Figure 26-19 .
Parallel scans may be simultaneous or non-simultaneous depending on CTRL2[SIMULT]. This bit only
applies to parallel operating modes and is ignored during sequential operating modes. During simultaneous
parallel scans, A and B converters scan synchronously using one set of shared controls (CTRL1 register).
During non-simultaneous scans, the A and B converters operate asynchronously with each converter using
its own independent set of controls (CTRL1 for A and CTRL2 for B). Refer to
Section 26.4.2.2, “CTRL2
Under Parallel Scan Modes ,” for more information.