How can I add flash programming capabilities to a custom-design board witg the SAME70 or SAMV71? For example, with the UC3-A3 (AVR32), I just expose TDI, TDO, TCK, TMS, RESET, GND/VDD, and voila: I connect a JTAG programmer and done. This option seems to be unavailable with the SAME70/V71.

What would be the equivalent for these SAM Cortex-M7 microcontrollers? The datasheet is non-explicit at best. I would seem that I need to connect the SWD interface as shown in Figure 60-1 or 60-2 of the SAME70 datasheet. However, every reference to this SWD feature (including the description of the SWD tag in electronics.SE.com !!) mention debug and test only. The evaluation board uses EDBG via USB, but that does not seem like a viable option for a custom design.

Any tips or pointers will be appreciated!

  • 1
    \$\begingroup\$ Pretty much any MCU with SWD is going to be able to program the flash memory by means of that - the specific algorithm by which a debug channel can cause flash writes varies by brand and model (for example sometimes you load a stub of code into RAM along with data and execute it, or call a factory ROM routine, or do a special sequence of memory write operations) but it is usually handled by existing software tools, you don't have to implement the details yourself. \$\endgroup\$ Nov 30 '19 at 5:20

Have a look at the schematic for the SAME70 Xplained PCB. The header marked "JTAG" contains the necessary signals for programming without the secondary CPU.

However, as the fine print in the MCU manual mentions, JTAG functionality is only for factory testing, and the SW-DP is what you would use with something like the JLINK. Image below is from the eval board user manual.

enter image description here

From the MCU datasheet:

The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level. It integrates a permanent pulldown resistor of about 15 kΩ to GND, so that it can be left unconnected for normal operations.

The JTAG Debug Port TDI, TDO, TMS and TCK is inactive. It is provided for Boundary Scan Manufacturing Test purpose only.


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