Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
31-65
Preliminary
Figure 31-39. Overlapping Consecutive Conversion Commands
31.4.6
Internal/External Multiplexing
31.4.6.1
Channel Assignment
The internal analog multiplexers select one of the 40 analog input pins for conversion, based on the
CHANNEL_NUMBER field of a Command Message.
shows the channel number assignments for the non-multiplexed mode. The 40 single-ended
channels are provided by the ADC.
Table 31-36. Non-multiplexed Channel Assignments
Input Pins
Channel Number in
CHANNEL_NUMBER Field
Analog
Pin Name
Other
Functions
Conversion Type
Binary
Decimal
AN0 to AN39
Single-ended
0000_0000 to 0010_0111
0 to 39
VRH
Single-ended
0010_1000
40
VRL
Single-ended
0010_1001
41
MUX Settle Time
and Sampling
AD Conversion
Minimum time necessary to perform a single
conversion after channel number is changed
MUX Settle Time
and Sampling
AD Conversion
Channel # Change
and Sample Start
Channel # Change
& Sample Start
(a) Command Execution Sequence for Two Non-Overlapped Commands
Conversion starts immediately after
channel # change. ADC sample time
should compensate for MUX internal
capacitance settling and for the sampling
on the sampling capacitor. If sample time
is not long enough then conversion
MUX Settle Time
& Sampling
AD Conversion
Sampling
AD Conversion
Channel # Change
and Sample Start
Channel #
(b) Command Execution Sequence for Two Overlapped Commands
MUX
Settle Time
Change
Sample
Start
Channel # changes before sampling starts leading to
more time for MUX internal capacitance to settle.
results will have reduced accuracy