Is there an issue with the QWIIC port on recent LTR-559 Breakout Boards?

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1

I am building a clock using an Interstate75W with a 64x32 LED matrix panel, an RV3028 real time clock breakout and a BME280 environment sensor, which all work fine.

I then bought an LTR-559 light sensor breakout to control brightness of the LEDs, as the web-page description said that Micropython PicoW support was provided.

I was delighted to find that the breakout board included a QWIIC port, which was not apparent from the description, so I connected it to the I75W with a QWIIC cable.

However, the demo program (pimoroni-pico/micropython/examples/breakout_ltr559/demo.py at main · pimoroni/pimoroni-pico · GitHub) failed to provide sensible readings, and an I2C scan failed to find the device, either with or without the other boards connected. I am confident that the SDA and SCL pins are correct, as the other boards work fine.

Thinking that the LTR-559 might be faulty, I bought another one, but that failed in exactly the same way.

Then I attached a QWIIC-to-Breakout Garden adapter to the original LTR-559, and it worked correctly via the adapter!

Has anyone else had this problem, or am I doing something wrong?

2

I have an almost identical setup. I75W, RV3028, BME280, LTR-559. My LTR-559 doesn’t have a QWICC connector on it. My 3 breakouts are soldered to a proto board and connected to the I75 via the QWICC connector on this.
Breakout Garden to STEMMA QT / Qwiic Adapter (pimoroni.com)

I use the LTR-559 to adjust the brightness of my LED matrix. I display the date time; indoor / outdoor temperature and humidity; and the barometric pressure.

I have a second BME280 using the alternate i2c address that reads the outdoor conditions.

I have a couple of spare LTR-559’s here, non have a QWICC connector on them though?

3

My two LTR-559s are Pimoroni PIM413, bought from The Pi Hut recently, and they really do have a QWIIC connector on them, though it is not visible on the product description pages on either Pimoroni or Pi Hut websites.
I also used the Pimoroni Breakout Garden to STEMMA QT/Qwiic Adapter on my RV3028, though my BME280 is Adafruit, which conveniently has two Qwiic connectors on it.

4

I have no doubt that if I ordered an LTR-559 now, it would come with a QWICC connector. I have other breakouts where the QWICC was added. So far, as far as I know, I haven’t had any issues using the QWICC connector on a breakout.

5

Have you clocked that Interstate uses GP20 and GP21 for I2C?

The LTR-559 example uses GP4 and GP5 by default, so you’ll need to tell it to use the alternate pins by changing line 8 to:

i2c = PimoroniI2C(**PINS_PICO_EXPLORER)

6

Hi Hel, yes, I am using GP20 and GP21, and it works fine using the Breakout Garden / Qwiic adapter, but it doesn’t work for me using the on-board Qwiic connector, which seems to be a recent addition.
I just tried it again - it works with the cable plugged into the adapter, but not when the same cable is plugged into the Qwiic connector.

7

Took me a couple of days to get this, but just to let you know I’ve just plugged one of the new LTR-559 breakouts via Qw/ST and it’s not showing up for me either 🤔

Investigating!

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8

Confirmed wiring error on the Qw/ST connector on this batch 😭

Please drop us an email at support@pimoroni.com with your shipping address and we’ll get some replacements sorted for you!

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