Is it possible to load code using a USB-TTL directly to D0, D1 pins?

Official Hardware Nano Family Nano Matter
1

I had a look at the Nano Matter and apparently it uses ATSAM-D11-D14A-MUT as USB-Bridge,
As far as I understood its function is to be used as USB-TTL to MGM240's UART.
I'm asking myself some questions :

  1. Why using a so sophisticated chip (ATSAMD) for a such simple function ? Wouldn't be FT232RL simpler ?
  2. Wanting to upload code without the ATSAMD, could I use a USB-TTL connected directly to Nano Matter D0 and D1 pins ?
2

A lot depends on the capabilities/features of the micro on the board. With an UNO, the bootloader - once programmed into the chip - can program a new piece of code using the hardware serial port.

Newer micros can be programmed using a dedicated high speed serial interface (not a UART). Some also support debugging too. In order to program and debug, a more sophisticated chip like one of the SAMD series is used.

In order to use one of the FT232 type devices, the target micro needs to have the ability to write to its own internal flash memory under software control.

I've no experience of the micro used in the Nano Matter so can't comment on whether it has the ability to write to its own internal flash memory under software control.

3

Thanks for your reply.
It makes sense using a SAMD series for debugging functions.
However, assuming that I don't need debug , (and SAMD as well) I'm going to try to upload code using MISO/MOSI pins as I successfully did with the UNO board.

Regards,

4

I don't think you will succeed. The Nano Matter is very different from the UNO, and as I see, the MCU on the Matter has no ISP interface to be programmed via SPI. The SWDIO interface is used for debugging AND programming of the MCU.

5

A small paragraph of the datasheet for the micro used on the nano matter says:

The MGM240S supports hardware debugging via 4-pin JTAG or 2-pin serial-wire debug (SWD) interfaces. It is recommended to expose the debug pins in your own hardware design for firmware update and debug purposes.

It implies that the way to program the device is via the SWD interface.

However it may be possible to program the chip via other interfaces IF the chip has instructions that allow it to write to it's own flash memory.

You would also need a bootloader program programming into the chip. This would still need the use of the SWD interface to get the first piece of code into the chip.

10

Thanks everybody for your valuable answers which have improved my knowledge about this fantastic board.

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