CLP Debug

LaunchPad Resource Portal  This wiki is open and can be edited by all! More information available @ www.ti.com/launchpad Hardware Tools, Documentation, Schematics, etc List of available LaunchPad hardware List of available BoosterPack plug-in modules Software Tools Software Development Environments Code Composer Studio (CCS) Energia Project TivaWare for C Series Other MSP430 Software Tools Other C2000 Software Tools Resources (Tutorials, Code examples & Projects) MSP430 LaunchPad C2000 LaunchPad Tiva C Series LaunchPads Hercules LaunchPads Share your LaunchPad-based projects here! Build Your Own BoosterPack (BYOB) BoosterPack Baseline Standard

Introduction

This guide introduces the ways to debug code running on the EK-TM4C1294XL Connected LaunchPad and also how to use the EK-TM4C1294XL as a debug adapter to program and debug other Tiva C series devices. This guide will use the terms In Circuit Debug, Debug In and Debug Out. They are defined below for the purpose of this document.

In Circuit Debug

This is the standard use case and is fully supported. In this mode the USB cable is plugged into the EK-TM4C1294XL at the debug connector. The TM4C123GH6PMI device on the launchpad acts as a USB to JTAG bridge and controls the JTAG signals to the target TM4C1294NCPDTI device on the launchpad. The ARM® standard 10 pin jtag connector (U6) is not used.

Debug In

In this mode an external JTAG adapter such as a uLink or jLink or XDS100 is used to control the JTAG signals to the TM4C1294NCPDT device on the LaunchPad. This mode is fully supported. The external JTAG adapter is connected to the ARM standard 10 pin jtag connector U6.

Debug Out

In this mode the TM4C123GH6PMI device on the LaunchPad is used to drive JTAG signals out through U6 to an external board. While this mode is known to work, it is not officially supported by TI.

In Circuit Debug

This mode requires no additional clarification. See Project 0 and other pages on this wiki for more information.

Debug In

When an external JTAG adapter is connected to U6 the TM4C123GH6PMI which drives the on board JTAG signals detects the presence of the external adapter. It then places all of its JTAG signal outputs in to a high impedance state allowing them to be driven directly from the external adapter. The TM4C123GH6PMI uses an internal weak pull up resistance attached through R40 to the U6 connector. By default the associate pin of U6 is grounded by the external adapter. Thus when the on board TM4C123GH6PMI senses a ground connection is present this is the trigger to tri-state the JTAG output signals.

Debug Out

To use the EK-TM4C1294XL as a debug adapter to program and debug other Tiva C series devices several resistors must be removed. Remove the following resistors: R8, R10, R11, R15, R16.

Optionally remove R6 and R7. Removing these resistors allows the external use of the virtual serial port. To use the virtual serial port wire the off-board TX and RX signals to the test points labeled TXD and RXD. These test points are a part of X1 on the schematic and board. The transmit line of the MCU being debugged goes to TXD. The receive line of the MCU being debugged goes to RXD. NOTE: These are digital signals not RS232 signals the voltage range of these signals is 0V to 3.3V.

The sense circuit that is used to detect an external debug attachment must be disabled. There are at least two methods of doing this. The first and preferred method is to remove R40. The alternate method is to disconnect the U6 pin associated with R40 from the ground signal on the external target board. Ground or low voltage must not be seen by the TM4C123GH6PMI GPIO pin associated with R40.

Once these changes have been made a standard 10 pin ribbon cable may be used to connect the LaunchPad to any external board with a similar connector. The TM4C123GH6PMI will now drive JTAG signals out through the cable and program and debug the external target. If the external board does not have standard ARM ten pin connector then wires may be connected to the labeled pins on the right side of X1.

Restoring JTAG after Debug Out

After performing debug out if you choose to restore in circuit debug or debug in the following must be done.

• Restore the removed resistors. Or populate X1 with a standard header and jumpers. This allows for future easy transfer from In circuit to debug out mode by installing or removing the jumpers on X1.
• R40 must in place to perform Debug In.