JTAGulator - Revision history

Hash: /* Issue discovering JTAG lines and a work-around */

2020-06-04T03:16:54Z

Issue discovering JTAG lines and a work-around

Hash: /* Issue discovering JTAG lines and a work-around */

2020-06-04T03:14:52Z

Issue discovering JTAG lines and a work-around

Hash: /* Issue discovering JTAG lines and a work-around */

2020-06-04T03:12:29Z

Issue discovering JTAG lines and a work-around

Hash at 03:11, 4 June 2020

2020-06-04T03:11:34Z

Hash at 03:09, 4 June 2020

2020-06-04T03:09:59Z

Hash at 03:07, 4 June 2020

2020-06-04T03:07:52Z

Hash at 02:50, 3 June 2020

2020-06-03T02:50:36Z

Hash: Created page with "The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by Joe Grand of [http://www.gr..."

2020-06-03T02:36:50Z

Created page with "The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by Joe Grand of [http://www.gr..."

New page

The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.
[[File:JTAGulator and Kenwood TH-D74.jpg|thumb|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout]]

@@ Line 1: / Line 1: @@
 The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.
 [[File:JTAGulator and Kenwood TH-D74.jpg|thumb|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout|alt=|none]]
-----
+=Issue discovering JTAG lines and a work-around=
 Initially hooking up the JTAGulator to the Kenwood TH-D74 amateur radio the JTAG pinout was not discovered. I figured perhaps the port I identified was incorrect or there may have been components removed disabling the JTAG port. I soldered wires to a completely different device that I verified with the components datasheet had JTAG and was indeed connected to the port I was using. Again, the JTAGulator did not identify the pinout.

@@ Line 8: / Line 8: @@
 I started running longer scans with the JTAGulator and probing each line with my oscilloscope to see what the waveform looked like. '''My hunch was correct, one of the data lines did not look like the rest!'''
-On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover" heights="200">
+On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed" heights="200">
 File:1 TRST no pullup.jpg|Top waveform is TRST line being driven by JTAGulator, notice it only drives to about 1.24V and VCC is 1.8V so needs to be closer to that.
 File:2 TRST no pullup.jpg|Bottom waveform is another line being driven by JTAGulator, notice it drives to about 1.62V and VCC is 1.8V so this is acceptable.

@@ Line 8: / Line 8: @@
 I started running longer scans with the JTAGulator and probing each line with my oscilloscope to see what the waveform looked like. '''My hunch was correct, one of the data lines did not look like the rest!'''
-On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover" heights="240">
+On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover" heights="200">
 File:1 TRST no pullup.jpg|Top waveform is TRST line being driven by JTAGulator, notice it only drives to about 1.24V and VCC is 1.8V so needs to be closer to that.
 File:2 TRST no pullup.jpg|Bottom waveform is another line being driven by JTAGulator, notice it drives to about 1.62V and VCC is 1.8V so this is acceptable.

@@ Line 8: / Line 8: @@
 I started running longer scans with the JTAGulator and probing each line with my oscilloscope to see what the waveform looked like. '''My hunch was correct, one of the data lines did not look like the rest!'''
-On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="nolines">
+On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover" heights="240">
 File:1 TRST no pullup.jpg|Top waveform is TRST line being driven by JTAGulator, notice it only drives to about 1.24V and VCC is 1.8V so needs to be closer to that.
 File:2 TRST no pullup.jpg|Bottom waveform is another line being driven by JTAGulator, notice it drives to about 1.62V and VCC is 1.8V so this is acceptable.

@@ Line 3: / Line 3: @@
 ----
-=== Issue discovering JTAG lines and a work-around ===
+===Issue discovering JTAG lines and a work-around===
 Initially hooking up the JTAGulator to the Kenwood TH-D74 amateur radio the JTAG pinout was not discovered. I figured perhaps the port I identified was incorrect or there may have been components removed disabling the JTAG port. I soldered wires to a completely different device that I verified with the components datasheet had JTAG and was indeed connected to the port I was using. Again, the JTAGulator did not identify the pinout.
 I started running longer scans with the JTAGulator and probing each line with my oscilloscope to see what the waveform looked like. '''My hunch was correct, one of the data lines did not look like the rest!'''
-On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover">
+On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="nolines">
 File:1 TRST no pullup.jpg|Top waveform is TRST line being driven by JTAGulator, notice it only drives to about 1.24V and VCC is 1.8V so needs to be closer to that.
 File:2 TRST no pullup.jpg|Bottom waveform is another line being driven by JTAGulator, notice it drives to about 1.62V and VCC is 1.8V so this is acceptable.

← Older revision		Revision as of 03:07, 4 June 2020
Line 1:		Line 1:
	The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.		The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.
−	[[File:JTAGulator and Kenwood TH-D74.jpg\|thumb\|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout\|alt=\|~~left~~]]	+	[[File:JTAGulator and Kenwood TH-D74.jpg\|thumb\|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout\|alt=\|none]]
		+	----
		+
		+	=== Issue discovering JTAG lines and a work-around ===
		+	Initially hooking up the JTAGulator to the Kenwood TH-D74 amateur radio the JTAG pinout was not discovered. I figured perhaps the port I identified was incorrect or there may have been components removed disabling the JTAG port. I soldered wires to a completely different device that I verified with the components datasheet had JTAG and was indeed connected to the port I was using. Again, the JTAGulator did not identify the pinout.
		+
		+	I started running longer scans with the JTAGulator and probing each line with my oscilloscope to see what the waveform looked like. '''My hunch was correct, one of the data lines did not look like the rest!'''
		+
		+	On both devices I tested the TRST line was pulled low using a 2.2k resistor per the recommendations in the manufacturers datasheet. The JTAGulator does not seem able to drive these lines hard enough to overcome this resistor value.<gallery mode="packed-hover">
		+	File:1 TRST no pullup.jpg\|Top waveform is TRST line being driven by JTAGulator, notice it only drives to about 1.24V and VCC is 1.8V so needs to be closer to that.
		+	File:2 TRST no pullup.jpg\|Bottom waveform is another line being driven by JTAGulator, notice it drives to about 1.62V and VCC is 1.8V so this is acceptable.
		+	File:3 TRST pullup.jpg\|Top waveform is TRST line being driven by JTAGulator along with a 1k resistor tied to VCC I added, notice it moves the signal up significantly so a low is 1V and high is 1.62V which is acceptable to the processor.
		+	File:5 TRST Overview.jpg\|Here is the test setup, you can see the test clips used to add the 1k resistor near the edge of the table to the TRST line I found by looking at each data line on the oscilloscope.
		+	File:6 TRST Overview.jpg\|Another view with the resistor at the edge of the table in focus.
		+	</gallery>

← Older revision		Revision as of 02:50, 3 June 2020
Line 1:		Line 1:
	The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.		The [http://www.grandideastudio.com/jtagulator/ JTAGulator] is an open source tool to help find On-Chip Debugging (OCD) interfaces. Designed by [[Joe Grand]] of [http://www.grandideastudio.com/ Grand Idea Studio] it can be used to find JTAG ports and UART's on embedded devices.
−	[[File:JTAGulator and Kenwood TH-D74.jpg\|thumb\|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout]]	+	[[File:JTAGulator and Kenwood TH-D74.jpg\|thumb\|JTAGulator connected to a Kenwood TH-D74 to determine JTAG pinout\|alt=\|left]]