MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
19-94
Freescale Semiconductor
19.4.6.2
External Multiplexing
The eQADC can use from one to four external multiplexers to expand the number of analog signals that
may be converted. Up to 32 analog channels can be converted through external multiplexer selection. The
externally multiplexed channels are automatically selected by the CHANNEL_NUMBER field of a
command message, in the same way done with internally multiplexed channels. The software selects the
external multiplexed mode by setting the ADC0/1_EMUX bit in either ADC0_CR or ADC1_CR
depending on which ADC will perform the conversion.
assignments for the multiplexed mode. There are 4 differential pairs, 40 single-ended, and, at most, 32
externally multiplexed channels that can be selected. Only one ADC can have its ADC0/1_EMUX bit
asserted at a time.
shows the maximum configuration of four external multiplexer chips connected to the
eQADC. The external multiplexer chip selects one of eight analog inputs and connects it to a single analog
output, which is fed to a specific input of the eQADC. The eQADC provides three multiplexed address
signals, MA0, MA1, and MA2, to select one of eight inputs. These three multiplexed address signals are
connected to all four external multiplexer chips. The analog output of the four multiplex chips are each
connected to four separate eQADC inputs, ANW, ANX, ANY, and ANZ. The MA pins correspond to the
Table 19-52. Multiplexed Channel Assignments
1
1
The two on-chip ADCs can access the same analog input pins but simultaneous conversions are not allowed. Also, when one
ADC is performing a differential conversion on a pair of pins, the other ADC must not access either of these two pins as
single-ended channels.
Input Pins
Channel Number in
CHANNEL_NUMBER Field
Analog
Pin Name
Other Functions
Conversion Type
Binary
Decimal
AN0 to AN7
Single-ended
0000_0000 to 0000_0111
0 to 7
Reserved
0000_1000 to 0000_1011
8 to 11
AN12 to AN39
Single-ended
0000_1100 to 0010_0111
12 to 39
VRH
Single-ended
0010_1000
40
VRL
Single-ended
0010_1001
41
(VRH–VRL)/2
Single-ended
0010_1010
42
75% x (VRH–VRL)
Single-ended
0010_1011
43
25% x (VRH–VRL)
Single-ended
0010_1100
44
Reserved
0010_1101 to 0011_1111
45 to 63
ANW
ANX
ANY
ANZ
—
—
—
—
Single-ended
Single-ended
Single-ended
Single-ended
0100_0xxx
0100_1xxx
0101_0xxx
0101_1xxx
64 to 71
72 to 79
80 to 87
88 to 95
DAN0+ and DAN0-
DAN1+ and DAN1-
DAN2+ and DAN2-
DAN3+ and DAN3-
Differential
Differential
Differential
Differential
0110_0000
0110_0001
0110_0010
0110_0011
96
97
98
99
Reserved
0011_0100 to 1111_1111
100 to 255
Summary of Contents for MPC5553
Page 5: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 2 Freescale Semiconductor...
Page 21: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 xvi Freescale Semiconductor...
Page 47: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 1 26 Freescale Semiconductor...
Page 163: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 4 20 Freescale Semiconductor...
Page 179: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 5 16 Freescale Semiconductor...
Page 561: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 13 38 Freescale Semiconductor...
Page 615: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 14 54 Freescale Semiconductor...
Page 707: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 17 68 Freescale Semiconductor...
Page 755: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 18 48 Freescale Semiconductor...
Page 873: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 19 118 Freescale Semiconductor...
Page 984: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 Freescale Semiconductor 21 41...
Page 985: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 21 42 Freescale Semiconductor...
Page 1019: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 22 34 Freescale Semiconductor...
Page 1129: ...MPC5553 MPC5554 Microcontroller Reference Manual Rev 5 25 90 Freescale Semiconductor...