COLL-ARM20-06IDC · Adapter with Signal Smoothing

Short description

Adapter board from the 20-pin ARM debugger connector (2 × 10 pin, 2.54 mm) to 6 pin (2 × 3, 2.54 mm) for TC2030-IDC, TC2030-IDC-NL and ECV3-06-IDC. The debug lines run through series resistors; every signal is brought out individually for probing.

Application

The 20-pin connector is standard on the debugger and long since the exception on the target. This board sits in between and takes the 6-pin 2.54 mm (0.1″) connector of a TC2030-IDC, TC2030-IDC-NL or ECV3-06-IDC on the target side — the same interface that still fits on a crowded board.

Series resistors — signal smoothing

SWO, SWCLK and SWDIO each run through 39 Ω. The resistor sits directly in the signal path and matches the driver output to the line, so overshoot and ringing come out smaller. That pays off above all with longer cables and high clock rates, where the edges would otherwise start to ring. The board is marked accordingly.

The 39 Ω are a default, not a fixed value. The resistors are 0603 and can be swapped with an ordinary soldering iron. Together with the test points this closes the loop: measure, change the value, measure again — on your own board, with your own cable.

SWO is present

Alongside SWCLK and SWDIO, SWO is routed to the interface and damped as well. The trace output is therefore available — for ITM output, say, without tying up a serial port on the target. Whether it can be used is up to the target MCU and the debugger; the line is there and is not cut off.

Reset can be isolated

The reset line carries a 0 Ω resistor instead of a damping one. It can be desoldered, which separates the debugger's reset from the target — useful wherever the target circuit drives its own reset, or when you need to establish whether a reset came from the debugger or from the circuit.

Test points for the oscilloscope

Every signal is additionally brought out to its own via. There is also a bare copper area with a via as a ground pickup.

That allows a short ground connection at the probe instead of the long clip. This is the difference from a plain adapter: the ground loop of the clip creates ringing that is not present in the circuit at all. The board is small, so the distances between signal and ground point stay short.

Pin assignment

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

Pin 2 on the debugger side is not connected.

Powering the target from the debugger — solder bridge, open as shipped

The bridge is open as shipped. Pin 1 on the target side is then fed from VREF alone; the debugger reads the operating voltage of the target circuit and feeds nothing in. Left alone, nothing happens here.

Closing the bridge puts pin 19 of the debugger on the same line. Many units carry a supply voltage there — the debugger then powers the target board, which saves a second connection on small setups without their own supply. Which voltage your debugger puts on pin 19 is in its documentation; check it against the target circuit before closing the bridge.

Technical data

• Debugger side: 20-pin header, 2 × 10, 2.54 mm pitch (ARM standard)
• Target side: 6 pin, 2 × 3, 2.54 mm pitch — for TC2030-IDC, TC2030-IDC-NL and ECV3-06-IDC
• Not suitable: the CTX variants (TC2030-CTX, ECV3-06-CTX) — they end in the 10-pin 1.27 mm (0.05″) Cortex connector
• Interface: ARM Cortex SWD, SWO routed
• Series resistors 39 Ω: SWO, SWCLK, SWDIO — 0603, replaceable
• Reset line: 0 Ω, desolder to isolate
• Test points: one via per signal, plus a bare ground area with via
• Powering the target from the debugger: solder bridge, open as shipped

Everything on one board

Damping, connector conversion and test points sit on one board. Assembled from separate parts, that means several adapters in a chain — each with its own transition in the signal path, and every transition is a place where the edge you were trying to smooth takes a hit.

Relation to the ARM20-CTX

The ARM20-CTX from Tag-Connect does the same job at the interface and stays in the range. The COLL-ARM20-06IDC is the choice when signal quality matters, or when you need to measure on the debug connection itself.

Included

The adapter board only. Cables and debugger are not included; any accessory shown in product photos is there for illustration.