Enviro-pHAT Interrupt Access?


#1

I have a Pi0W with an Enviro-pHat on the pi-bus running on Stretch. The I2C probe software (i2cdetect) sees all the devices on the pHAT. On the Enviro-pHat, are either of INT1 (pin 11) or INT2 (pin 9) on the LSM303D connected to any of the GPIO pins on the Raspberry Pi expansion bus? If so, what are the pi-bus pin numbers? Are the interrupt lines hardware setup for Active High or Active Low interrupts? Can I use interrupts to signal when a change in Acceleration/Magnetic Field/Temp changes (e.g. use GPIO edge interrupts)? The project is designed to use changes in acceleration to signal a wake up event.


#2

Have a look at this. https://pinout.xyz/pinout/enviro_phat#
It looks like for the most part it just uses i2c.


#3

If you check the product page for just about any Hat or pHat Pimoroni makes, there is a link to the pinout. ;)


#4

Thank you. I have looked at the pi-bus pin out; but without a schematic it is hard to tell if there are jumpers or other means to connect chip capabilities to the pi. One can hope that some of these capabilities may be just a jumper away from realization ;-)!


#5

My understanding is, if its not shown on the pinout, its not physically wired to a PIN. You might be able to do it yourself, likely won’t be easy though.
There are boards like this though that have those pins accessable, https://www.pololu.com/product/2127


#6

Indeed, the interrupts are not physically wired to any pins on the header.

Making any real use of interrupts on the Pi is difficult, anyway, you wouldn’t be achieving anything like the ultra-low-power sleep modes you could accomplish on a micro-controller…


#7

Thank you! This is very helpful.


#8

Also, thanks for the observation on low power. All engineering seems to be a series of tradeoffs; right now the cost vs performance vs latency vs power drain seems to favor the Pi0W for the intended application.


#9

My apologies for the plethora of replies. It says I can edit a previous reply, but I do not see the “quote reply” button the pop-up pane suggests. In any event, Wish I’d found the Pololu board earlier. It is exactly what I was hoping for in the Enviro-pHat. Perhaps a small wiring hat is in order to map the Pololu board onto a piHat is in order. Thanks again!


#10

I’ve used boards like this, https://shop.pimoroni.com/products/protozero with great success.


#11

Thank you. An excellent starting point.


#12

Here are some of my projects if you want to have a look see, https://1drv.ms/f/s!AjOYwiwlwDtpgUMsp2qnevKpGEHb
So far I’ve been using the Adafruit version of what I posted above. I only just got my hands on the Pimoroni version and haven’t put one to good use yet. If you use a stacking header you can put it between your Pi and pHat or Hat. More than one if you want, I used two Proto Hats in one project. There wasn’t room on one for all I wanted to hook up.
I’ve added RTC breakout boards to a few of my projects with the Proto hats.


Blue colored board in the middle. I just solder the header to the Proto Hat, then cut the excess protruding pins on the back side off. Then use jumper wire to connect it up to the GPIO.