QADC64E Enhanced Mode Operation
MPC561/MPC563 Reference Manual, Rev. 1.2
14-14
Freescale Semiconductor
configures the corresponding signal as an input. The software is responsible for ensuring that DDR bits are
not set to one on signals used for analog inputs. When the DDR bit is set to one and the signal is selected
for analog conversion, the voltage sampled is that of the output digital driver as influenced by the load.
NOTE
Caution should be exercised when mixing digital and analog inputs. This
should be isolated as much as possible. Rise and fall times should be as large
as possible to minimize AC coupling effects.
There are two special cases to consider for the digital I/O port operation. When QACR0[EMUX] bit is set,
enabling external multiplexing, the data direction register settings are ignored for the bits corresponding
to PORTQA[2:0], which are the three multiplexed address output signals, MA[2:0]. The MA[2:0] signals
are forced to be digital outputs, regardless of the data direction setting, and the multiplexed address outputs
are driven. The data returned during a port data register read is the value of the multiplexed address latches
which drive MA[2:0], regardless of the data direction setting.
14.3.5
Control Register 0
Control Register 0 defines whether external multiplexing is enabled, assigns external triggers to the
conversion queues and sets up the QCLK prescaler parameter field. All of the implemented control register
fields can be read or written but reserved fields read zero and writes have no effect. Typically, they are
written once when software initializes the QADC64E and are not changed afterwards.
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
Field DDQ
A7
DDQ
A6
DDQ
A5
DDQ
A4
DDQ
A3
DDQ
A2
DDQ
A1
DDQ
A0
DDQ
B7
DDQ
B6
DDQ
B5
DDQ
B4
DDQ
B3
DDQ
B2
DDQ
B1
DDQ
B0
SRESET
0000_0000_0000_0000
Addr
0x30 4808 (DDRQA_A); 0x30 4C08 (DDRQA_B); 0x30 4809 (DDRQB_A); 0x30 4C09 (DDRQB_B)
Figure 14-8. Port
x
Data Direction Register (DDRQA and DDRQB)
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
Field
EMUX
—
TRG
—
PRESCALER
SRESET
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
Addr
0x30 480A (QACR0_A); 0x30 4C0A (QACR0_B)
Figure 14-9. Control Register 0 (QACR0)
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...