Zero Availability

[BJHenry]

Interestingly Digikey lists the Zero as obsolete.

[dlabun]

Well I'm pretty well convinced Arduino silently killed off the Zero. I am going to start designing my Zero equivalent board, should anyone be interested PM me.

[david_prentice]

I have an original "Zero Pro".  It was later called "M0 Pro".

I also have a Chinese clone "M0" i.e. without the EDBG chip.

Personally,  I find it very pleasant to have an onboard EDBG chip.    Much like STM32 Nucleo boards have an onboard ST-Link debugger.

From the Manufacturer's point  of view,   a debugger chip costs about a $1 and uses a bit of pcb real estate.
From Arduino's point of view,  it depends on how much Microchip charge for the EDBG chip.

The Zero would never be a mass market board.   Nor would it be able to compete with Nucleo as a useful development platform.    M4 Nucleos show just what good performance is possible.   i.e. much better than M0 SAMD or the M3 Due SAM3X.


Mind you,   CMSIS-DAP is provided for free by ARM.   The Chinese could put CMSIS-DAP into whatever chip they wanted.    And produce a Zero clone.

David.

[dlabun]

I'm actually very surprised there isn't any Zero clones out there alrady with an on board debug chip. Even Sparkfun and Adafruit don't include on board debugging. I've already spoken with a debugging tool manufacturer, the cost per board is extremely low so I would definitely include it.

[westfw]

I've already spoken with a debugging tool manufacturer, the cost per board is extremely low

Riiiight.  The debugger chip in the Zero is probably the most expensive component on the board; a AT32UC3A4256 that normally sells for about $8 (compared to $3-4 for the SAMD chip.)
Yeah, some of the more modern "development board with built-in-debugger" boards have cheaper chips (an ATmega32u4 on the Uno WiFi2, for instance), and if you happen to be the CHIP manufacturer, you can probably get (your own) chips really cheap.  But for a relatively small manufacturer like Arduino, I'd bet it more than doubles the (maufacturing) cost of the board.  (You'll note that none of the MKR boards include debugging.)  (OTOH, the Zero was never "inexpensive", so the debugger costs should be covered, and there's little excuse for the Board to have just disappeared from stocks)

CMSIS-DAP is provided for free by ARM.   The Chinese could put CMSIS-DAP into whatever chip they wanted.    And produce a Zero clone.

Or, you know, provide a $10 CMSIS-DAP debug probe...

[BJHenry]

The Xplain series of development boards use an ATMega32U4 as a programmer/debugger- they call it the mEDGB. The schematics and firmware are freely available, and there is even this project to make a DIY mEDGB standalone programmer.
I'm sure if you wanted to get enterprising you could design your own board with an mEDGB onboard.

[david_prentice]

A Chinese ST-Link dongle costs about $3.   You can connect it to the SWD header on a Due board but the Dupont cables get in the way of a shield.

Rowley is perfectly happy with using an ST-Link with a non-ST Target.
Keil should be happy too.

Of course Atmel Studio only supports CMSIS-DAP or JLink debugger with its proprietary chips.

You can install JLink firmware into a ST-Link dongle but Segger do not allow you to use non-ST targets.

If you use the JTAG header on Due or M0 boards the JTAG ribbon does not interfere with shields.
You need to buy a 1.27mm pitch 5x2 cable and adapter board which is as expensive as the ST-Link dongle.  e.g. adapter + cables

I believe that NXP evaluation boards have got CMSIS-DAP debugger and 1.27mm pitch 5x2 header.   So you only need the ribbon cable.

In theory,  the Microchip SNAP is both cheap and can do SWD debugging.

Regarding EDBG using a UC32 chip.   ST use their STM32F103.   NXP use their LPC.  Freescale used their K20.  ...
I would guess that any reasonably powerful chip could run the CMSIS-DAP firmware.
You would certainly AVOID using the mEDBG mega32U4.   It is too painful.

David.

[david_prentice]

Rowley works fine with ST-Link on the Due
I tried Pickit4.    Neither Rowley or AS7 worked.
I have not tried SNAP since Pickit4 failed.

I know that ATMEL-ICE works in AS7, Rowley, Keil on the Due.

Rowley connects fine to the M0 via ST-Link.   But then whinges about locked memory on the SAMD21.

I am not particularly worried about the M0 because I have the M0 Pro for development.
I presume that all the MKR owners have discovered convenient ways to develop code.

David.

[dlabun]

For the debugger only, If I was to do a pilot run of 250 boards today it would cost $2.25 for the chip (STM32) and $0.24 for the license. At 1,000 boards the chip cost drops to about $1.70.

I do have one technical issue to work out with the debugger and if we find a solution I am going to move forward with designing some boards.

[david_prentice]

I don't see the need for a debugger in a final product.

Surely you install your firmware into your product via an external programmer (or native bootloader if the chip has one)
You can install your own DFU or OTA loader for any subsequent updates.

You only need the debugger when you are developing in the first place.

Of course you may be intending your boards for a class of 250 students.   In which case you do a deal with a manufacturer for their "evaluation boards".

It would be interesting to know how many Zero / M0 Pro boards were ever manufactured.    I suspect they are quietly retiring the Zero.   But it would be better to just say so.

Incidentally,  the SAM JTAG header on ATMEL-ICE is wired backwards.   (which seems CRAZY)

David.

[dlabun]

It's been rather odd since the two Arduinos merged back together. Almost immediately they silently killed off the Nordic nRF52 based board Arduino.org was just about to release. Here we are 2-ish years later and now the Zero is MIA.

I am going to keep working on my replacement board and maybe float the idea again over the summer once I have something workable in my hands.

[westfw]

It also seems to be the case that CMSIS/DAP (the USB-level protocol for talking to SWD debug features) and/or debuggers are relatively chatty and inefficiency across USB, meaning that people see a noticeable improvement going from a debugger that only supports "full speed" USB (like the 32u4) to one that supports "high-speed" USB (like the  UC32)

The Xplain series of development boards use an ATMega32U4 as a programmer/debugger- they call it the mEDGB.

The Xplained Pro boards have the UC32 EDBG chip.
The Xplained Mini boards have the 32u4 mEDBG.
The Curiosity Nano boards have a new SAMD "nEDBG" chip.

I'm sure if you wanted to get enterprising you could design your own board with an mEDGB onboard.

Sure.  And it would probably cost about twice as much as a board without a debugger.
Those $10 development boards sold by chip vendors are nice, but they're not a very accurate indicator of how much it would cost to build a similar board on your own.  Those boards are "loss-leaders"; the next best thing to a free sample; designed to attract devotees, and partially paid for from the "sales&marketing" budget...
I do wish that the current incarnation of Arduino would show more signs of having their manufacturing arm "in good shape."  :-(