Overview

When working with Simplelink connected MCU Launchpads, it is common to need to connect multiple boards to the same host in order to perform wireless communications among them.

This application note describes the necessary hardware modifications to connect these boards to the same JTAG scan chain and the necessary configurations in Code Composer Studio to properly acknowledge this mixed setup.

References

• XDS Target Connection Guide - Multiple Devices
• Target Configuration - Custom Configurations
• Multi-core debug with CCS
• Debugging with Multiple Debug Probes

The procedure

In order to aggregate two or more boards, a few customizations to both hardware and software must be made.

Hardware

The Hardware modification is needed to chain the devices according to the schematics shown in the Multiple Devices section of the XDS Target Connection Guide - check the section References above.

Isolation jumpers

As shown in the photograph below, the Simplelink Connected MCU Launchpads have jumpers that isolate several connections and conveniently expose the four JTAG signals: TDI, TDO, TCK and TMS. In addition, the Reset signal is also exposed and is useful for flash programming operations.

One additional convenience feature of the latest Launchpad models is that these signals can also be exposed via the boosterpack connector. In order to do that, some soldering skills and jumpers or 0Ω SMD resistors are required.

• As shown in the first photograph below, the jumper pads are designed for 0603 resistors (Vishay P/N CRCW06030000Z0EB), but they can also be fitted with 0805 resistors (Vishay P/N CRCW08050000Z0EB) as shown in the second photograph below.

Interconnections

All interconnections must be done with the wires as short as possible to prevent delays, crosstalk and noise.

• Remove the TDO JTAG isolation jumper of the first Launchpad.
  • If an external Debug Probe will be used, remove all JTAG isolation jumpers of this Launchpad.
• Remove all the JTAG isolation jumpers of the second Launchpad.
• Interconnect the signals TMS, TCK and Reset across all Launchpads.
• Connect a wire between the lower TDO pin (closer to the device) to the lower TDI pin (closer to the device) of the second Launchpad.
• Connect a wire between the upper TDO pin (closer to the XDS110) to the lower TDO pin (closer to the device) of the second Launchpad.

The following table summarizes the connections:

If three or more Launchpads are needed, simply extend the connections between TDO → TDI and, at the last Launchpad, connect its TDO → TDO of the XDS110.

Software

The only software aspect that is required to configure the multi-device system is the Target Configuration File (.ccxml), which is configured following the steps shown in the Target Configurations - Custom Configurations page - check the section References above. This file must describe how the connections and the order of devices is arranged in hardware.

Create a new target configuration file, add the first device on the scan chain and click on the tab Advanced to add the other device(s).

Once there, click on the button Add to add the second device.

On the Devices tab, use the Filter selection by to reduce the number of options and select the second device.

Once all the other devices are added, highlight the Debug Probe entry at the top of the tree and make sure the configuration options are compatible with all devices in the scan chain. Click Save to keep all changes.

Once the Debugger is launched, it should show all the devices in the Debug view.

Resources

Code Composer Studio
Related Technical Documents
TI E2E Technical Forums

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Last updated: May 17 2022 13:23 Central Time