
MOTOROLA
Chapter 14. QADC64E Enhanced Mode Operation
14-15
Programming the QADC64E Registers
Port B signals are referred to as PQB[7:0] when used as 8-bit general-purpose digital input
or output signals. It is configured as a digital input or digital output using the data direction
register, DDRQB. When Port B is configured as an input, a read of the PORTQB register
returns the actual PQB[7:0] signal values. When Port B is configured as an output, the
contents of port register PQB are driven on the port B signals. Port B can also be used as
non-multiplexed analog inputs AN[51:44]. In external multiplexed mode four signals can
be used as multiplexer analog inputs, ANw, ANx, ANy, ANz.
During a port data register read, the actual value of the signal is reported when its
corresponding bit in the data direction register defines the signal to be an input. When the
data direction bit specifies the signal to be an output, the content of the port data register is
read. PORTQA and PORTQB are not initialized by reset..
14.3.4
Port Data Direction Register
The port data direction registers (DDRQA and DDRQB) are associated with the Port A and
information. Any bit set to one in this register configures the corresponding signal as an
output. Any bit cleared to zero in this register 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.
MSB
0
123
456
7
8
9
10
11
12
13
14
LSB
15
Field PQA7 PQA6 PQA5 PQA4 PQA3 PQA2 PQA1 PQA0 PQB7 PQB6 PQB5 PQB4 PQB3 PQB2 PQB1 PQB0
SRESET
Undefined
Addr
(PORTQA) 0x30 4806; 0x30 4C06
(PORTQB) 0x30 4807; 0x30 4C07
ANALOG CHANNEL:
AN59 AN58 AN57 AN56 AN55 AN54 AN53 AN52
AN51 AN50 AN49 AN48 AN47 AN46 AN45 AN44
MULTIPLEXED ADDRESS OUTPUTS:
MA2
MA1
MA0
MULTIPLEXED ANALOG INPUTS:
ANz
ANy
ANx
ANw
Figure 14-7. Port A Data Register (PORTQA), Port B Data Register (PORTQB)
Table 14-8. PORTQA, PORTQB Bit Descriptions
Bits
Name
Description
0:7
PQA[7:0]
Port A signals are referred to as PQA when used as an 8-bit input/output port. Port A can also be
used for analog inputs (AN[59:52]), and external multiplexer address outputs (MA[2:0]).
8:15
PQB[7:0]
Port B signals are referred to as PQB when used as an 8-bit input/output port. Port B can also be
used for non-mulitplexed (AN[51:44]) and multiplexed (ANz, ANy, ANx, ANw) analog inputs.