ARM JTAG connector information

The CodeWarrior Ethernet TAP ARM® JTAG probe has a 20-pin connector which automatically supports target system signal levels from 1.8V to 3.3V.

The following figure shows the pin assignments of the probe ARM JTAG connector.

Figure 1. Ethernet TAP probe ARM JTAG connector pin assignments

The following table lists ARM JTAG signal names, direction, pin numbers, descriptions, and drive capabilities for the probe ARM JTAG connector.

Table 1. Ethernet TAP probe ARM JTAG signal directions
ARM JTAG pin	Signal mnemonic	Signal direction	Description
1	VTREF	From target system	2MOhm pull-down, plus 0.01uF load
2	VSUPPLY	- n/a -	VSUPPLY is not used by the Ethernet TAP
3	TRST	From Ethernet TAP probe connector	50mA driver
4	GND	- n/a -
5	TDI	From Ethernet TAP probe connector	50mA driver
6	GND	- n/a -
7	TMS	From Ethernet TAP probe connector	50mA driver
8	GND	- n/a -
9	TCK	From Ethernet TAP probe connector	50mA driver
10	GND	- n/a -
11	RTCK	From target system	17pF load
12	GND	- n/a -
13	TDO	From target system	17pF load²
14	GND	- n/a -
15	SRST	Bi-directional	Open-drain. 100Ohm to ground when asserted by Ethernet TAP, 22pF load when not asserted¹
16	GND	- n/a -
17	DBGRQ	From Ethernet TAP probe connector	50mA driver
18	GND	- n/a -
19	DBGACK	From target system	17pF load²
20	GND	- n/a -

The table below provides a general description of each ARM JTAG signal and the operational requirements.

Note: All ARM JTAG signals must meet accepted standards for ARM JTAG signal design. To ensure proper and stable operation between the Ethernet TAP probe for ARM JTAG and the target system, the ARM JTAG signals must meet the requirements listed in the following table.

Table 2. Ethernet TAP probe ARM JTAG signal recommendations and requirements
ARM JTAG pin	Signal mnemonic	Requirement
1	VTREF	Must be wired to the target system. The Ethernet TAP probe uses this signal to determine if power is applied to the target. The signal is also used as a voltage reference for the signals driven by the Ethernet TAP probe (TRST, TDI, TMS, TCK, SRST, DBGRQ). VTREF should be connected to target Vcc through a 1KOhm pull-up.
2	VSUPPLY	May be wired to the target processor. The Ethernet TAP probe does not currently use this signal.
3	TRST	Must be wired to the target system. The Ethernet TAP probe drives the TRST output with up to 50 mA. Note: TRST must not be connected to SRST. The probe must be able to independently assert these two signals.
4	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
5	TDI	Must be wired to the target system. The Ethernet TAP probe drives the TDI output with up to 50 mA. The TDI trace run should be kept as short as possible and maintain a "two-signal-width" spacing from any other parallel dynamic signal trace.
6	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
7	TMS	Must be wired to the target system. The Ethernet TAP probe drives the TMS output with up to 50 mA. The TMS trace run should be kept as short as possible and maintain a "two-signal-width" spacing from any other parallel dynamic signal trace.
8	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
9	TCK	Must be wired to the target processor. The Ethernet TAP probe drives the TCK output with up to 50 mA. The TCK trace run should be kept as short as possible and maintain a "two-signal-width" spacing from any other parallel dynamic signal trace.
10	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
11	RTCK	May be wired to the target processor. The Ethernet TAP probe does not require this signal.
12	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
13	TDO	Must be wired to the target processor. TDO is an output from the target processor and an input to the Ethernet TAP probe. The TDO trace run should be kept as short as possible and maintain a "two-signal-width" spacing from any other parallel dynamic signal trace. TDO should have a series termination resistor located near the target processor.
14	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
15	SRST	Must be wired to the target processor. The Ethernet TAP probe drives the SRST output with up to 50 mA. During reset, the probe drives SRST to ground through a 100Ohm resistor. Note: TRST must not be connected to SRST. The probe must be able to independently assert these two signals.
16	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
17	DBGRQ	May be wired to the target processor. The Ethernet TAP probe does not currently use this signal.
18	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.
19	DBGACK	May be wired to the target processor. The Ethernet TAP probe does not currently use this signal.
20	GND	Must be wired to the target system. GND is connected directly to the ground inside the Ethernet TAP probe.