A.11.2. JTAG

Figure A.15 shows the pinout of the JTAG connector J18 and Table A.16 list the JTAG and signals, see also Table 3.21. All JTAG active HIGH input signals have pull-up resistors, DGBRQ is active LOW and has a pull-down resistor.

Note

The term JTAG equipment refers to any hardware, typically this is RealView ICE or Multi-ICE, that can drive the JTAG signals to devices in the scan chain. All pins not listed in Table A.16 are connected to ground.

Figure A.15. JTAG connector J18

JTAG connector J18

Table A.16. JTAG signals

Signal

Pin

Description

3V3

1, 23.3V supply (and reference voltage) to JTAG interface unit

nTRST

3

Open-collector test reset (from JTAG equipment)

TDI

5

Test data in

TMS

7

Test mode select

TCK

9

Test clock

RTCK

11

Return TCK

TDO

13

Test data out

nSRST

15

Open collector system reset (bidirectional)

DBGRQ

17Debug request to processor

DBGACK

19Debug acknowledge from processor

nICEDETECT

20Detects debug device connected to baseboard. The external devices connects pin 20 to ground.

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