
Functional Description and Application Information
General Purpose I/O - PTB[0…2]
MM912F634
Freescale Semiconductor
124
4.17
General Purpose I/O - PTB[0…2]
The three multipurpose I/O pins can be configured to operate as documented in the table below.
The alternate function of PTB2, PTB1 and PTB0 can be configured by selecting the function in the corresponding module (e.g.
TIMER). The selection with the highest priority will take effect when more than one function is selected.
4.17.1
Digital I/O Functionality
All three pins act as standard digital Inputs / Outputs with selectable pull-up resistor.
4.17.2
Alternative SCI / LIN Functionality
For alternative serial configuration and for debug and certification purpose, PTB0 and PTB1 can be configured to connect to the
internal LIN and / or SCI signals (RxD and TxD).
Figure 34 shows the 4 available configurations.
Figure 34. Alternative SCI / LIN Functionality
4.17.3
Alternative PWM Functionality
As an alternative routing for the PWM channel (0 or 1) output, the PortB 2 (PTB2) can be configured to output one of the two
configured in the Port B Configuration Register 2 (PTBC2).
Table 144. General purpose I/O - Operating modes
Priority
Function
PTB2
PTB1
PTB0
Chp/Pg
1 (H)
2.5 V Analog Input
AD2
AD1
AD0
4.18/124
2
Timer Input Capture / Output Compare
TIMCH2
TIMCH1
TIMCH0
4.17/111
3
LIN / SCI - Rx / Tx (PTB0…1) or PWM (PTB2)
PWM
Tx
Rx
4.13/91
4 (L)
5.0 V Input Output
PTB2
PTB1
PTB0
current
Serial
Communication
Interface (SCI)
LIN Physical
Layer Interface
4 Channel Timer
Module
PTB0/AD0/TIM0CH0/Rx
PTB1/AD1/TIM0CH1/Tx
PTB2/AD2/TIM0CH2/PWM
LIN
TIM0CH3
Rx
Tx
Rx
Tx
Serial
Communication
Interface (SCI)
LIN Physical
Layer Interface
4 Channel Timer
Module
PTB0/AD0/TIM0CH0/Rx
PTB1/AD1/TIM0CH1/Tx
PTB2/AD2/TIM0CH2/PWM
LIN
TIM0CH3
Rx
Tx
Rx
Tx
Serial
Communication
Interface (SCI)
LIN Physical
Layer Interface
4 Channel Timer
Module
PTB0/AD0/TIM0CH0/Rx
PTB1/AD1/TIM0CH1/Tx
PTB2/AD2/TIM0CH2/PWM
LIN
TIM0CH3
Rx
Tx
Rx
Tx
Serial
Communication
Interface (SCI)
LIN Physical
Layer Interface
4 Channel Timer
Module
PTB0/AD0/TIM0CH0/Rx
PTB1/AD1/TIM0CH1/Tx
PTB2/AD2/TIM0CH2/PWM
LIN
TIM0CH3
Rx
Tx
Rx
Tx
Mode 0 (default)
Mode 1 (external SCI)
Mode 2 (external LIN)
Mode 3 (observe)