setup the pin correspondingly as an output with initial high value, output
with initial low value, output or input. Example:
echo high > /sys/class/gpio/gpio39/direction
echo in > /sys/class/gpio/gpio40/direction
Outputs can be controlled by writing to the value file like this:
echo 0 > /sys/class/gpio/gpio39/value
echo 1 > /sys/class/gpio/gpio39/value
Pin sense value can be read regardless of its direction by reading the value
file:
cat /sys/class/gpio/gpio39/value
cat /sys/class/gpio/gpio40/value
Of course user is free to write a C program to access these files instead of
using the shell examples above.
JTAG PORT
The JTAG connector allows a debugger to talk via a JTAG (Joint Test Action
Group) port directly to the core. Instructions may be inserted and executed
by the core thus allowing SAM9261 memory to be programmed with code
and executed step by step by the host software.
For more details refer to IEEE Standard 1149.1 - 1990 Standard Test
Access Port and Boundary Scan Architecture and SAM9261 datasheet.
Pin #
Signal Name
Pin #
Signal Name
1
VCC
2
VCC
3
ICE_NTRST
4
GND
5
TDI
6
GND
7
TMS
8
GND
9
TCK
10
GND
11
RTCK
12
GND
13
TDO
14
GND
15
ICE_NRST
16
GND
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