mc68331cpv20b1 Freescale Semiconductor, Inc, mc68331cpv20b1 Datasheet - Page 83

• Manufacturer Part Number: mc68331cpv20b1
• Description: Mc68331 32 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

4.6.5 Pin State During Reset
4.6.5.1 Reset States of SIM Pins
MC68331
USER’S MANUAL
It is important to keep the distinction between pin function and pin electrical state clear.
Although control register values and mode select inputs determine pin function, a pin
driver can be active, inactive or in high-impedance state while reset occurs. During
power-up reset, pin state is subject to the constraints discussed in 4.6.7 Power-On
Reset.
Generally, while RESET is asserted, SIM pins either go to an inactive high-impedance
state or are driven to their inactive states. After RESET is released, mode selection
occurs, and reset exception processing begins. Pins configured as inputs during reset
become active high-impedance loads after RESET is released. Inputs must be driven
to the desired active state. Pull-up or pull-down circuitry may be necessary. Pins con-
figured as outputs begin to function after RESET is released. Table 4-18 is a summary
of SIM pin states during reset.
Module
CPU32
QSM
GPT
Pins that are not used should either be configured as outputs, or (if
configured as inputs) pulled to the appropriate inactive state. This de-
creases additional I
ply level.
Freescale Semiconductor, Inc.
For More Information On This Product,
Table 4-17 Module Pin Functions
SYSTEM INTEGRATION MODULE
PQS[6:4]/PCS[3:1]
PGP[6:3]/OC[4:1]
DD
Go to: www.freescale.com
PGP[2:0]/IC[3:1]
PQS3/PCS0/SS
PGP7/IC4/OC5
Pin Mnemonic
PWMA, PWMB
BKPT/DSCLK
DSI/IFETCH
PQS1/MOSI
PQS0/MISO
DSO/IPIPE
PQS7/TXD
PQS2/SCK
caused by digital inputs floating near mid-sup-
PCLK
RXD
PAI
NOTE
Discrete Output
BKPT/DSCLK
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
Discrete Input
DSI/IFETCH
DSO/IPIPE
Function
RXD
4-41
4