Texas Instruments XDS110 User Manual page 24

Functional Description and Operation
How to do a debug reset (Test-Logic-Reset) with the XDS110 (JTAG and cJTAG):
For JTAG:
dbgjtag -f @xds110 -r
For cJTAG:
dbgjtag -f @xds110cjtag -r
dbgjtag puts the XDS110 probe and connected targets into the JTAG test-logic-reset (TLR) state. To do
this, it both toggles the nTRST pin on the debug header and executes a JTAG state transition to TLR
through the TMS and TCK pins. Thus, if a target device does not have an nTRST pin, this command still
puts it into TLR through the JTAG state transistion.
The -r command can be used in conjunction with other commands. For example:
dbgjtag -f @xds110 -S integrity -r
The -r command is always done first. In this case, dbgjtag puts the probe and target into TLR before
executing the scan integrity test.
How to use the XDS110 GPIO pins:
The XDS110 includes 4 GPIO pins on the AUX connector that can be controlled by the user. dbgjtag
includes a command to configure, write, and read these GPIO pins:
dbgjtag -f @xds110 -Y gpiopins, config=number, write=number, read=boolean, mask=number
The GPIO pins are accessed by reading and writing the lower four bits of the number value. GPIO 3 and
GPIO 2 are inputs into the XDS110. GPIO 1 and GPIO 0 are outputs from the XDS110. GPIO 1 and GPIO
0 are initially configured as inputs (hiZ). The user must configure these as outputs to enable these pins.
config=number sets the direction of each GPIO. Writing a b'1' for a GPIO configures it as an output.
Writing a b'0' for a GPIO configures it as an input. Only GPIO 1 and GPIO 0 can be configured as outputs.
write=number sets the output level of the GPIO pins configured as outputs. Writing a b'0' to a GPIO sets
the output level low. Writing a b'1' to a GPIO sets the output level high.
read=boolean selects if the command also reads the current value of the GPIO pins. "boolean" may be
either "yes" or "no". If "yes," the value of the pins is read and displayed.
mask=number provides a bit mask to limit which GPIOs are to be affected. If a GPIO bit is set to b'0' in
the mask, that GPIO is not affected by the config, write, or read commands. If not supplied, all pins are
affected by the other commands.
Using the -v (verbose) command with the -Y gpiopins command modifies the output to display the current
config value and always read the pins, and display the result.
Examples:
dbgjtag -f @xds110 -Y gpiopins, config=0x3, write=0x0
Configure GPIO 3 and GPIO 2 as inputs and GPIO 1 and GPIO 0 as outputs. Set the values of GPIO 1
and GPIO 0 both to b'0'.
dbgjtag -f @xds110 -Y gpiopins, config=0x3, write=0x3, mask=0x2
The mask limits the operations to GPIO 1. Configure GPIO 1 as an output and set its value to b'1'. The
configuration and values for the other three GPIOs are not affected.
dbgjtag -f @xds110 -Y gpiopins, read=yes
Read the current value of the GPIO pins.
dbgjtag -f @xds110 -Y gpiopins -v
Display both the configuration and current value of the GPIO pins (following other output displayed by the
verbose mode).
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XDS110 Debug Probe
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SPRUI94 – January 2017
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