Boundary-Scan Test Interface

16

The boundary-scan interface conforms to the IEEE Std. 1149.1 – 1990, Standard Test Access Port and Boundary-Scan Architecture. (Refer to this standard for an explanation of the terms used in this section and for a description of the TAP controller states.) The Intel® StrongARM® SA-1100 Microprocessor (SA-1100) supports only JTAG continuity testing.

16.1Overview

The boundary-scan interface provides a means of driving and sampling all the external pins of the device irrespective of the core state. This function permits testing of both the device’s electrical connections to the circuit board and (in conjunction with other devices on the circuit board having a similar interface) testing the integrity of the circuit board connections between devices. The interface intercepts all external connections within the device, and each such “cell” is then connected together to form a serial shift register (the boundary-scan register). The whole interface is controlled via five dedicated pins: TDI, TMS, TCK, nTRST, and TDO. Figure 16-1shows the state transitions that occur in the TAP controller. Note that all SA-1100 signals participate in the boundary scan. However, in the case of the PWR_EN pin, the contents of the scan latches are not placed on the pin. This is to prevent a scan operation from turning off power to the SA-1100.

Figure 16-1. Test Access Port (TAP) Controller State Transitions

Test-Logic Reset

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

 

 

 

 

 

 

tms=1

 

 

 

 

 

 

 

 

 

tms=0

Run-Test/Idle

 

 

 

Select-DR-Scan

 

 

 

Select-IR-Scan

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=0

 

 

 

 

tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Capture-DR

 

 

Capture-IR

 

 

 

 

 

tms=1

 

tms=0

 

tms=1

 

tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Shift-DR

 

 

 

Shift-IR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1 tms=0

 

 

 

 

tms=1 tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Exit1-DR

 

 

 

Exit1-IR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

 

 

 

 

 

tms=1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=0

 

 

 

 

tms=0

 

 

 

 

 

 

Pause-DR

 

 

Pause-IR

 

 

 

 

tms=0

 

tms=1 tms=0

tms=0

 

tms=1 tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Exit2-IR

 

 

 

 

 

 

Exit2-DR

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

 

 

 

tms=1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Update-DR

 

 

 

 

Update-IR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tms=1

 

tms=0

 

 

tms=1

 

 

tms=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SA-1100 Developer’s Manual

16-1

Page 361
Image 361
Intel SA-1100 manual Boundary-Scan Test Interface, Test Access Port TAP Controller State Transitions