Using available ports on a device for end-product testing


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The MIPI Debug Working Group has standardized a way to utilize functional interfaces for debug or test. This technology is called MIPI NIDnTSM (Narrow Interface for Debug and Test). It allows better debug support in production or near-production mobile terminal units.

NIDnT technology defines low pin count, reliable and high-performance debug interfaces that can be used in deployed mobile terminal units. These interfaces provide access to basic debug, trace of application activity, and HW test capability by reusing already existing functional interfaces.

In some cases, these interfaces are accessible at the packaged boundary of a mobile terminal. This technology provides the means to use functional interfaces for either functional or debug purposes. One or more functional interfaces (e.g., MMC card slot for trace and USB for basic debug) may be used to provide debug capability. It should be noted, however, that NIDnT technology does not aim to replace current technologies such as debugging via a serial interface (e.g., GDB using a UART, or on-device debug agent).

Table 1 Summary of Test/Debug Capabilities Supported by NIDnT
Capability Interface with Single-Ended Electricals Interface with Differential Electricals
Basic Debug

2-pin (Min-Pin) Debug

  • IEEE 1149.7
  • ARM(R) Serial Wire Debug (SWD)
  • UART
  • Vendor Defined Single-Ended Debug

4-pin High-Speed Debug

  • Vendor Defined Differential Debug
5-pin Legacy Debug
  • IEEE 1149.1
6-pin Modified Legacy Debug
  • Modified IEEE 1149.1 Standard with return clock (deprecated)

Single-Ended Trace

  • MIPI Parallel Trace Interface (MIPI PTI)
  • Vendor Defined Single-Ended Trace

High-Speed Trace

  • MIPI High-Speed Trace Interface (MIPI HTI)
  • Vendor Defined Differential Trace
User Defined Vendor Defined Single-Ended Vendor Defined Differential

The current version of the NIDnT Specification addresses the reuse of the following interfaces:  microSD, USB (USB 2.0 and USB Type-C), and Display (HDMI and DisplayPort (DP)).

Note: This specification is available to only to MIPI Alliance members. For information about MIPI Alliance membership, visit Join MIPI.