Affordable programmer-debugger probe by Seeed

[rei-vilo]

A programmer-debugger probe is a very useful and "must have" tool for embedded system development.

Today, there is no affordable offer.

Segger used to list the J-Link Edu mini probe at an affordable price; it is no longer the case. Price went from USD20 to USD70.

The Xiao expansion board provides the pogo pins to make the connections, alas only for some boards, SAMD, nRF52840 and RP2040. The ESP32 requires full JTAG, except the latest C-series which include the debugger.

I am not a bing fan of the fragile pogo pins featured by the Xiao Expansion Board. Once the Xiao is mounted in the final design, the SWD pads are no longer accessible unless they are rerouted. The 2x5 0.05" connector is very compact, and some variants even include power and UART RX/TX signals.

I would replace the USB connector by a SWD connector on the Xiao boards. The USB connector takes too much space and is of limited use.

The Xiao SAMD turned debugger provides DAPLink but does not support all the Xiao boards.

Seeed could take inspiration of the Raspberry Pi Debug Probe brings the best-in-class value, with its fool-proof connector, software tools suite and UART RX/TX signals

References:

• Roadmap of Seeed XIAO: You Decide What We Build Next!
• Why should we consider redesign the SWD interface on the XIAO
• The $5 programmer-debugger

[limengdu]

OpenOCD, BlackMagic Probe, DAPLink, PyOCD are a few open source solutions, which one do you think is better for us to use?

[rei-vilo]

I would go for OpenOCD, as I am using it against the boards I work with. Now, I have no experience with BlackMagic.

[limengdu]

preliminary design

[rei-vilo]

@limengdu Thank you for sharing the design. As always, some questions and some comments.

• What are the features of the board? Does it include an MCU for the toggle wheel, the display and the debugger?
• How to connect the board to a PC?
• Where is placed or connected the device under test? Does the connection rely on pgo pins?
• Is the board compatible with the new 14 + 9 form-factor of the Xiao Plus?
• I would recommend placing all the connectors, including standard IOs, extended IOs and debug pins, on the same side.
• Grove UART is fine, but what about a Grove I²C connector as well?
• I am not a big fan of RGB LEDs. I would trade them for another feature to match the targeted budget.

[CWGwaltney]

i think it is important to build the XIAO ecosystem... and to implement as many features on a board as the GPIO will permit

[limengdu]

Let me answer your questions:

1. This Debug Tool integrates SWD/JTAG debugger function, UART to TTL function and power consumption statistics, focusing on the development and debugging scenarios of all XIAO development boards.
2. Development board built-in USB-C interface, can be directly connected to the computer via cable.
   3.XIAO and Debug Tool are directly connected through the motherboard, no other wiring troubles.
   4.Support. Correction, it's a 14+8 pin design, and will lead the extra 8 GPIOs out through the row mother.
3. There may not be enough space on one side, currently XIAO is planning a consistent design language, we will use some development board standard size to design XIAO Gadget, but we will try to place the interfaces that may be used on the same side.
4. Please note that the UART is designed to match the TTL function of the Debug Tool, it is not an expansion board, and the IIC does not play any role for this board.
5. This is a single-colour LED, the cost will not be particularly affected. My vision is a very beautiful desktop ornament, lighting effects we will design extremely cool, with the choice of baud rate, I believe you will like such a delicate gadget.