COLL-ARM20-10-IDC · 20-pin ARM to TC2050-IDC, JTAG/SWD

Short description

Adapter board between the 20-pin ARM debug header (2 × 10, 2.54 mm) and the ten-pin IDC connector of the TC2050 Plug-of-Nails™ cables. With series resistors, plug-in jumpers for supply and nTRST, measuring points and the pinout printed on the board.

Connections

Full pin assignment: further down this page.

Compatible: SEGGER J-Link, Keil ULINK, ST-LINK/V2 and the other debuggers using the classic 20-pin 2.54 mm ARM connector.

Not, or not directly, compatible

• 12-pin — Lattice HW-USBN-2B: through the adapter board TC-LATTICE-10
• 14-pin, 2 × 7, 2 mm — Xilinx Platform Cable II: through the adapter board TC2050-XILINX
• 14-pin, 2 × 7, 2.54 mm (0.1″) — Renesas E1 / E2 / E8a / E20: through the adapter board TC-RENESAS

Easily confused: There is also a 20-pin Cortex connector on 1.27 mm (IAR I-Jet, Keil ULINK Pro, SEGGER J-Trace) — same pin count, half the pitch.

Application

Your debugger has the classic 20-pin ARM header — J-Link, ULINK, many older tools — while your board carries the ten-pin Tag-Connect footprint. This board sits in between. It replaces the TC2050-ARM2010 and carries the same assignment, with changes that save time at the bench.

Series resistors — signal smoothing

Every signal line carries a series resistor. They damp reflections on long lines and unterminated ends — the most common reason for a debugger losing the connection unpredictably. The technical term for this is series termination; what is at stake is signal integrity on the run between debugger and target. 0603 package, so they can be swapped where your setup calls for different values.

Five values are included

Ten resistors each in 22 Ω, 27 Ω, 33 Ω, 39 Ω and 43 Ω come with the board — 0603 package, the same as fitted. That lets you match the damping to your own circuit without ordering anything first: measure, swap the value, measure again.

Jumpers instead of a soldering iron

Two decisions come up again and again with this adapter: whether pin 5 is ground or carries the supply from the debugger, and whether nTRST is brought out on pin 9. On the original these are solder bridges. Here they are plug-in jumpers — change them over instead of desoldering, even at a populated bench. As shipped, the jumper for pin 5 is on GND (better signal integrity) and pin 9 is open.

Pinout printed on the board

Both modes are in the silkscreen — JTAG and SWD. Whoever holds the adapter sees which signal is on which pin without looking for a datasheet.

Measuring points

Every signal line has a via for a probe tip, plus a bare ground plane with a via for the short ground connection. That way you measure on the running setup instead of hunting along the cable.

Pinout

Which signal sits where, and what is in the signal path:

Pins 2 and 17 on the debugger side are not connected. Pin 5 on the cable side is selected with a three-position jumper: VCC, open or GND. As shipped it is on GND — the better choice for signal integrity, as long as the target board brings its own supply.

Technical data

• Cable side: 10-pin IDC, 2.54 mm — for TC2050-IDC and TC2050-IDC-NL
• Series resistors: 0603 package, replaceable
• Reset: 0 Ω, can be desoldered to break the line
• Jumpers: pin 5 (VCC / open / GND), pin 9 (nTRST)
• Measuring points: one via per signal, plus a bare ground plane

How it relates to the TC2050-ARM2010

Same task, same assignment. What differs: the series resistors, the plug-in jumpers, the printed pinout and the measuring points.

Included

The adapter board and the resistor set: ten each of 22 Ω, 27 Ω, 33 Ω, 39 Ω and 43 Ω in 0603 package. Cable and debugger are not included.