Is the Qwiic Shield supposed to work on the Arduino MEGA2560 R3? Mine works fine on all my Unos, but not on the MEGA. I chained up 4 devices, plugged them in the Qwiic Shield and ran an I2C Scanner sketch. On the Unos, all devices were found; on the MEGA, none were found. In both cases, the last device in the chain showed it was receiving power. I then used the Qwiic to male-jumpers cable to connect directly to the MEGA (Yellow-SCL, Blue-SDA, Red-3.3V, Black-GND). This worked fine, but it defeats the neat-and-tidy advantage of the Qwiic system.
Thanks,
Bill
Hi Bill,
Unfortunately, the Qwiic Shield runs the SDA and SCL lines to A4 and A5. This works fine on an Uno, but other Arduinos like the Mega don’t have the I2C bus on those two pins. This is an issue we are aware of and we have a revision request submitted but there is no ETA on when that will be completed.
While not ideal, you could either just run a green-wire or jumper wire solution on the Qwiic Shield from A4 and A5 to SDA and SCL or you could tap into the HV side of the level shifting circuit and re-route that to the SDA and SCL pins on the Qwiic Shield. Tapping into that would require soldering to the surface mounted resistors so it might be more hassle than it is worth. If you intend to go that route, I would recommend referring to the Eagle board and schematic files available for download from the “Documents” tab on the product page.
I hope this helps explain the issue and gives you some options to work around this incompatibility issue.
They used to literally advertise it as being compatible with links to buy a MEGA on the Qwiic breakout product page. Which we did, thinking it would be workable or would likely be workable with a MEGA off the shelf or with minor modifications. You could go with a Ruggeduino at least, which lets you select that it will still work with A4 and A5 without having to change anything. Those are are about $100 USD though, a bit expensive for a single MEGA but do have some advantages over a standard one.
The whole Qwiic setup is still a bit clunky overall in terms of parts that are available and issues with the ones that are. Crimping the pins to make connectors is a huge pain to have to do but custom length or material wires are not available easily and certainly not from Sparkfun. We have been working with some suppliers to be able to source them for in house use in quantity in silicone at least.
Would still be nice if they were gold plated and not tin plated.
Would also be nice if turning off the terminating resistors wasn’t necessary to do for EVERY single Qwiic part by literally using a razor blade to cut the traces.
Thanks all. Jumping SCL and SDA to A5 and A4 works for now.