Chapter 3: Hardware
CAN-Engine
3-4
3.3
Am186ES PIO lines
The Am186ES has 32 pins available as user-programmable I/O lines. Each of these pins can be used as a
user-programmable input or output signal, if the normal shared function is not needed. A PIO line can be
configured to operate as an input or output with or without a weak pull-up or pull-down, or as an open-drain
output. A pin’s behavior, either pull-up or pull-down, is pre-determined and shown in the table below.
After power-on/reset, PIO pins default to various configurations. The initialization routine provided by
TERN libraries reconfigures some of these pins as needed for specific on-board usage, as well. These
configurations, as well as the processor-internal peripheral usage configurations, are listed below in Table
3.1.
PIO
Function
Power-On/Reset status
CAN-Engine Pin No.
CAN-Engine Initial
P0
Timer1 in
Input with pull-up
J2 pin 20
Input with pull-up
P1
Timer1 out
Input with pull-down
J2 pin 29
Input with pull-down
P2
/PCS6/A2
Input with pull-up
J2 pin 24
Input with pull-up
P3
/PCS5/A1
Input with pull-up
J2 pin 15
Input with pull-up
P4
DT/R
Normal
J2 pin 38
Input with pull-up Step 2
P5
/DEN/DS
Normal
J2 pin 30
Input with pull-up
P6
SRDY
Normal
J2 pin 35
Input with pull-down
P7
A17
Normal
U3 pin 22
A17
P8
A18
Normal
U3 pin 23
A18
P9
A19
Normal
J2 pin 10
A19
P10
Timer0 out
Input with pull-down
J2 pin 12
Input with pull-down
P11
Timer0 in
Input with pull-up
U7 EE pin 5
Input with pull-up
P12
DRQ0/INT5
Input with pull-up
J2 pin 5
Output for LED/EE/HWD
P13
DRQ1/INT6
Input with pull-up
J2 pin 11
Input with pull-up
P14
/MCS0
Input with pull-up
J2 pin 37
Input with pull-up(ET)
P15
/MCS1
Input with pull-up
J2 pin 23
Input with pull-up
P16
/PCS0
Input with pull-up
J1 pin 19
/PCS0
P17
/PCS1
Input with pull-up
J2 pin 13
CAN, ADC, CF select
P18
CTS1/PCS2
Input with pull-up
J2 pin 22
Input with pull-up
P19
RTS1/PCS3
Input with pull-up
J2 pin 31
Input with pull-up
P20
RTS0
Input with pull-up
J2 pin 27
Input with pull-up
P21
CTS0
Input with pull-up
J2 pin 36
Input with pull-up
P22
TxD0
Input with pull-up
J2 pin 34
TxD0
P23
RxD0
Input with pull-up
J2 pin 32
RxD0
P24
/MCS2
Input with pull-up
J2 pin 17
Input with pull-up
P25
/MCS3
Input with pull-up
J2 pin 18
Input with pull-up
P26
UZI
Input with pull-up
J2 pin 4
Input with pull-up*
P27
TxD1
Input with pull-up
J2 pin 28
TxD1
P28
RxD1
Input with pull-up
J2 pin 26
RxD1
P29
/CLKDIV2
Input with pull-up
J2 pin 3
Input with pull-up*
P30
INT4
Input with pull-up
J2 pin 33
Input with pull-up
P31
INT2
Input with pull-up
J2 pin 19
Input with pull-up
* Note: P26 and P29 must NOT be forced low during power-on or reset.
Table 3.1 I/O pin default configuration after power-on or reset