Analog-to-Digital Converter (ADC)
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 26-21

26.5 Functional Description

The ADC’s conversion process is initiated by a sync signal from one of two input pins (SYNCx) or by

writing 1 to a STARTn bit.

Starting a single conversion actually begins a sequence of conversions, or a scan of up to 8 single-ended

or differential samples one at a time in sequential scan mode. The operation of the module in sequential

scan mode is shown in Figure 26-18.

Figure 26-18. Sequential Mode Operation of the ADC

Scan sequence is determined by defining eight sample slots in ADLST1/2 registers, processed in order

SAMPLE0-7 during sequential scan or in order SAMPLE0-3 by converter A and in order SAMPLE4-7 by

converter B in parallel scan. SAMPLE slots may be disabled using the SDIS register.

The following pairs of analog inputs can be configured as a diff erential pair: AN0-1, AN2-3, AN4-5, and

AN6-7. When configured as a differential pair, a reference to either member of the differential pair by a

sample slot results in a differential measurement using that differential pair.

AN3
AN2
AN1
AN0 V+
VREFL Channel Select
V– ADCA 12
Single-Ended vs
Crossbars allow AN0-3
to be stored in samples 4-7,
or AN4-7 to be stored in
samples 0-3
Differential
12 +
ADOFS[0:3]
13
Zero Crossing Logic
+

ADHLMT[4:7]
>
ADRSLT[0:3]
Zero Crossing
or Error Limit
Interrupt
ADLLMT[4:7]
<
12 12 +
ADOFS[4:7]
13
Zero Crossing Logic
+
ADRSLT[4:7]
12
AN7
AN6
AN5
AN4 V+
VREFL Channel Select
V– ADCB
Single-Ended vs
Differential
12
ADHLMT[0:3]
>
ADLLMT[0:3]
<
Test Data
(From CPU)
Test Data
(From CPU)
ADC2
ADC1
ADC0
End of
Scan B
Interrupt
End of
Scan A
Interrupt
IRQ Logic