This device is used to program various Atmel designed processors.

It has one serious fault, in the that sockets are wired back to front but otherwise it works well. The dumb wiring is the main reason for this page. I got it working fine once and now forget how it it's broken so need to rediscover the stupidity yet again.

I got the PCBA version of this device in 2019 for £47, they now cost £90 in 2022. Microchip outpace inflation like nobody else.

The key in the port is on the wrong side so you can either plug the cable in back to front (not recommend) or cut the notch off your cable and turn it around and plug it the right way around at the other end (recommended but I don't accept liability for any error). Maybe Atmel (now MCHP) should just employ competent engineers.

PS. MCHP will sell you mis-wired cables so you do not need to do the above, but having mis-wired cables in your collection may be even worse.

          SAM                          AVR
          KEY                          KEY  
TMS  TCK  TDO  TDI  SRST     GND  VTG  SRST TRST GND
 2    4    6    8    10       2    4    6    8   10
 1    3    5    7     9       1    3    5    7    9
VTG  GND  GND  TRST GND      TCK  TDO  TMS  NC   TDI

Both sockets contain the same signals just wired to
different pins (the JTAG standard and ATMEL non-standard).


PIN SAM    AVR   SWD(*) CORTEX(?)
 1  VTG    TCK   Vref   VCC/VREF
 2  TMS    GND   SWIO   SWDIO/TMS
 3  GND    TDO   GND    GND
 4  TCK    VTG   CLK    SWDCLK/TCK
 5  GND    TMS   GND    GND
 6  TDO    SRST  SWO    SWO/TDO
 7  TRST   NC    KEY    KEY
 8  TDI    TRST  NC     NC/TDI
 9  GND    TDI   GNDd   GND
10  SRST   GND   RST    nRESET

(*) Adafruit SWD adapter
(?) Adafruit Cortex SWD adapter

JTAG ATMEGA2560 ATMEGA32
VTG  VCC        VCC
GND  GND        GND
TCK  PF4        PC2
TDO  PF6        PC4
TMS  PF5        PC3
TDI  PF7        PC5