mcf5282 Freescale Semiconductor, Inc, mcf5282 Datasheet - Page 543

• Manufacturer Part Number: mcf5282
• Manufacturer: Freescale Semiconductor, Inc

28.4.2.2 Port QB Digital I/O Signals
Port QB signals are referred to as PQB[3:0] when used as a 4-bit digital input/output port. In addition to
functioning as analog input signals, the port QB signals are also connected to the input of a synchronizer
during reads and may be used as general-purpose digital inputs when the applied voltages meet V
V
Each port QB signal is configured as an input or output by programming the port data direction register
(DDRQB). The digital input signal states are read from the port QB data register (PORTQB) when
DDRQB specifies that the signals are inputs. The digital data in PORTQB is driven onto the port QB
signals when the corresponding bits in DDRQB specify output. See
Direction Register (DDRQA &
28.4.3
The QADC has two external trigger signals, ETRIG2 and ETRIG1. Each external trigger input is
associated with one of the scan queues, queue 1 or queue 2. The assignment of ETRIG[2:1] to a queue is
made by the TRG bit in QADC control register 0 (QACR0). When TRG = 0, ETRIG1 triggers queue 1 and
ETRIG2 triggers queue 2. When TRG = 1, ETRIG1 triggers queue 2 and ETRIG2 triggers queue 1. See
Section 28.6.5, “Control Registers
28.4.4
In non-multiplexed mode, the QADC analog input signals are connected to an internal multiplexer which
routes the analog signals into the internal A/D converter.
In externally multiplexed mode, the QADC allows automatic channel selection through up to four external
4-to-1 multiplexer chips. The QADC provides a 2-bit multiplexed address output to the external
multiplexer chips to allow selection of one of four inputs. The multiplexed address output signals, MA1
and MA0, can be used as multiplexed address output bits or as general-purpose I/O when external
multiplexed mode is not being used.
MA[1:0] are used as the address inputs for up to four 4-channel multiplexer chips. Because the MA[1:0]
signals are digital outputs in multiplexed mode, the state of their corresponding data direction bits in
DDRQA is ignored.
28.4.5
In external multiplexed mode, four of the port QB signals are redefined so that each represent four analog
input channels. See
Freescale Semiconductor
IL
requirements.
External Trigger Input Signals
Multiplexed Address Output Signals
Multiplexed Analog Input Signals
Table
Analog Input
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3
Multiplexed
28-1.
ANW
ANX
ANY
ANZ
Table 28-1. Multiplexed Analog Input Channels
DDRQB).
“Control Registers.”
Even numbered channels from 0 to 6
Odd numbered channels from 1 to 7
Even numbered channels from 16 to 22
Odd numbered channels from 17 to 23
Channels
Section 28.6.4, “Port QA and QB Data
Queued Analog-to-Digital Converter (QADC)
IH
28-5
and