MSP430

2011

Ultra-Low Power | High Integration | Easy-to-Use

“How To” Series: JTAG

Introduction

Purpose– Provide a brief but informative technical overview in “HOW-TO” use

the MSP430 JTAG interface

Objectives– Discuss What is JTAG?– Discuss how JTAG applies to MSP430 devices– Discuss Interface capabilities– Discuss Design considerations

What is JTAG? “JTAG”- Joint Test Action Group

– Originally and industry group formed to develop methodology for testing circuit board assemblies after manufacture

Industry standard IEEE Std. 1149.1-1990 Synonymous with

– Debugging, Memory programming and/or Boundary scan testing 4 or 5 wire physical interface

– TDI (Test Data In), TDO (Test Data Out), TCK (Test Clock), TMS (Test Mode Select), TRST (Test Reset) optional

No standard connector or adapter HW– Vendor-specific, often with extensions that use the JTAG interface

Reference: Wikipediahttp://en.wikipedia.org/wiki/Joint_Test_Action_Group

How JTAG applies to MSP430 devices

All MSP430 devices are debugged and primarily programmed using JTAG– Standard 4-wire JTAG– Custom 2-wire “SBW” JTAG (supported on select MSP430 devices)

MSP430 uses a 2x7 14-pin header for JTAG connectivity– Reduced pin headers used on some eZ430 HW for SBW-only

Note Boundary Scan is not supported on MSP430 devices today

In-system & BSL are options for memory programming, but only a JTAG interface can be used to debug

JTAG can be disabled to protect SW IP

Interface capabilities: 4-Wire

General Connections(see Hardware Tool’s User’s Guide and device-specific datasheets for more information)

MSP430 4-Wire JTAG Signal Implementation Overview

Devices TEST Pin 4-Wire

20-and 28-pin MSP430F1xx devices* YES YES

64-, 80-, and 100-pin MSP430F1xx/4xx devices * NO YES

MSP430F21x1 family * YES YES

14-, 20-, 28-, and 38-pin MSP430F2xx devices YES YES

64-, 80-, and 100-pin MSP430F2xx devices * NO YES 14-, 16-, 20-, 28-, and 32-pin MSP430G2xx devices YES YES MSP430F5xx/6xx devices YES YES

Pin Naming for SBW-capable devices:

RST = RST/SBWTCK

TEST = TEST/SBWTDIO

* These devices do not support the SBW option

All MSP430’s support 4-wire mode A RST connection to the JTAG

header is not required on devices that DO NOT support SBW (e.g. 100pin ‘1xx)

TEST must be connected when present the device

Interface capabilities: 2-Wire SBW

General Connections(see Hardware Tool’s User’s Guide and device-specific datasheets for more information)

MSP430 2-Wire JTAG Signal Implementation Overview

Devices TEST Pin 2-Wire SBW

20-and 28-pin MSP430F1xx devices * YES NO

64-, 80-, and 100-pin MSP430F1xx/4xx devices * NO NO

MSP430F21x1 family * YES NO

14-, 20-, 28-, and 38-pin MSP430F2xx devices YES YES

64-, 80-, and 100-pin MSP430F2xx devices * NO NO 14-, 16-, 20-, 28-, and 32-pin MSP430G2xx devices YES YES MSP430F5xx/6xx devices YES YES

* These devices do not support the SBW option

When physical fuse blow IS needed (e.g. 2xx devices):

– Header connection of TEST/VPP required – R2 is required to protect the TCK pin

When physical fuse blow IS NOT needed (e.g. all 5xx/6xx devices):

– Omit header connection to TEST/VPP– R2 = 0 Ohm

C2 must not exceed 2.2nF to assure reliable SBW communication

Design considerations JTAG pins are often multiplexed in the device

– Consider using non-JTAG functions in-application carefully to avoid conflicts with JTAG tools & communication signals

Using a larger capacitor on RST in-application is sometimes favorable to help filter noise that might cause unwanted resets

– This is acceptable in-application, but limit to 2.2nF for purposes of using JTAG

Keep routing of JTAG/RST/TEST signals as short as possible & isolated from other circuitry

– Protects against noise coupling into the application during debug– Helps limit exposure of JTAG/RST pins to unwanted spikes due to noise, ESD, etc.

When one or more JTAG pins are not used, please refer to the device-specific User’s Guide section “Connection of Unused Pins” for guidance

When programming via JTAG, keep in mind 4-wire JTAG is ~3x faster than using SBW

References

MSP430 Hardware Tools User's Guide– Describes the hardware of the Texas Instruments MSP-FET430 Flash Emulation

Tool, the primary development tool for the MSP430, as well as a broad selection of other MSP430 target boards and development platforms.

MSP430 Programming Via the JTAG Interface – Describes the functions required to erase, program, and verify the memory module

of the MSP430 using the JTAG communication port (4-wire & 2-wire “SBW”) for use when developing custom programming solutions; an example implementation is provided.

Your specific MSP430 device’s datasheet & Family User’s Guide

Thank you!