The version of the IoT board I just got has no J4. Looking at the schematic SWDIO and SWCLK are not routed to the edge connectors. So how does one connect a debugger?
The connector is under the board. For more details look at the store page for the Nano 33 IoT under Programming and Debugging Port.
You can likely use the Sparkfun ISP Pogo Adapter to connect to the pads without soldering directly onto the PCB.
Most Arduino users do not use a debugger but use printf debugging.
Thanks for posting.
I looked at the store page and the only underside photo does not show J4 that I can find. I think some of the other boards like MKR WiFi 1010 have 6 large solder pads though they are not marked. My IoT board does not have these 6 pads.
J4 is not marked and there are not 6 but 5 dots. Just left of the Arduino logo. They are in a 2x3 configuration, one middle pin missing.
You can download the Eagle ZIP file and then drop the *.brd file here to look a the signal traces.
Search for SWC and SWD to get the to serial wire debug lines. The other signals are 3.3, GND and Reset.
Thanks a whole case of cold ones. I was having problems finding a viewer.
For the next poor slub in my tracks here are the pics. One is the front/top layer and the other is the bottom/back. I included both so my work can be verified. Actually 2nd pic is in next post. Newbie dweebs are only allowed one pic.
Front / top layer
I do this for burning the bootloader, but I don't think it's feasible to hold the adapter in place by hand while doing anything more than the shortest debugging session. You lose use of one hand and must be very careful to hold the adapter steady because the slightest movement will cause a pogo to lose its tenuous alignment on the pad. A jig would be ideal though. But it sounds like captainaubrey is fine with soldering to the pads, and that's a quick and simple solution.
Sometimes the supertech took a day off so I had to do a bit of soldering to keep the debug/integration going. I hated tacking wires onto those chips with the 0.4mm pin pitch, especially if I had to raise a lead. But no guts, no glory.