AN1740 Freescale Semiconductor / Motorola, AN1740 Datasheet - Page 29

• Manufacturer Part Number: AN1740
• Description: Applications Using the Analog Subsystem on MC68HC05JJ/JP Series Microcontrollers
• Manufacturer: Freescale Semiconductor / Motorola

Channel Select
Bus
AN1740
MOTOROLA
TCMP
TCAP
PB4
AN4
V
PB1
AN1
PB2
AN2
PB3
AN3
OTHER CONNECTIONS TO PB1 THROUGH PB4 HAVE BEEN OMITTED FOR CLARITY
SS
CHANNEL SELECT BUS
NOTE:
(VREF) • (MUX1) • (MUX2) • (MUX3) • (MUX4)
V
–
AOFF
+
V
DD
The VREF, MUX1, MUX2, MUX3, and MUX4 bits in the AMUX register
control which signals or pins are connected to the channel select bus.
The MUX1:MUX4 bits can select any or all PB1:PB4 pins with no
interlocks and connect them to the channel select bus. When none of the
MUX1:MUX4 bits are set, the channel select bus is connected to either
the internal V
MUX1:MUX4 bit is set again, then it opens the V
regardless of the state of the VREF bit.
The simple channel multiplexers do not include any automatic break-
before-make or make-before-break control of multiple simultaneous
changes. Therefore, the user must control the multiplexers in the proper
sequence to avoid shorting two channels together during the transition.
Unless the user has determined that switching transients are not a
VREF
MUX1
MUX2
MUX3
MUX4
V
SS
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 12. Analog Channel Bus
Go to: www.freescale.com
DD
(VREF) • (MUX1) • (MUX2) • (MUX3) • (MUX4)
or V
SS
depending on the state of the VREF bit. If any
TO COMPARATOR INPUT BUS
DD
Analog Signal Multiplexers
or V
DENOTES
INTERNAL
ANALOG V
SS
VREF
MUX1
MUX2
MUX3
MUX4
AMUX
Application Note
connection
SS
29