The problem with this call, in my opinion, is it forces you to specific a pin which will now be used as an input and an edge mode which I don't require for my application. In other words, I needed to retain the state of variables in SRAM which this call allows. I didn't want that to happen on every wakeup from sleep. I would have used the deep sleep version but due to the way the puck starts up it causes a flicker in the e-paper display. Ultimately this is the call I was looking for. This call is exactly the same as the previous one with the addition of a seconds argument. System.sleep(uint16_t wakeUpPin, uint16_t edgeTriggerMode, long seconds)

For that we need the last variant of sleep call. Notice, however, that there is no option to pass a timeframe. Unlike the deep sleep call your code will continue to run when the Photon wakes up having preserved all variables in SRAM. This is great for applications where the press of a button or flip of a switch is meant to wake up the device. This call will put the STM32 into stop mode and wait for an external interrupt to wake it up. System.sleep(uint16_t wakeUpPin, uint16_t edgeTriggerMode) If your application does a lot of one time setup or has a lot of stuff stored in memory keep reading as this call might not be the best for you because you'll have to do it all again when the Photon wakes up. This is the function that will give you the most power saving bang for your buck. Don't expect it to pick up where it left off. It stops execution of code and waits for the specified number of seconds to pass and then starts running your code from the beginning of the setup() function. With the SLEEP_MODE_DEEP option passed as the first argument the Photon will put the STM32 into standby mode (more on this below). This call is closer to what we are looking for. System.sleep(SLEEP_MODE_DEEP, long seconds) I would have preferred something like System.sleepWiFi() to make it more explicit. While the WiFi module is sleeping, nothing else is. In my opinion the function is a bit of a misnomer. If your RGB LED is active it will begin to breath white indicating it is no longer connected to the network. All this call does is shut down the BCM WiFi module for the time specified.

The problem is, it returns immediately and continues executing code. Grab the stats, make this call with 300 seconds as the argument and wait for it to return.

This is the call I tried in my hockey puck code. So let's look at a couple of the calls from the documentation. The System.sleep() calls encapsulate BOTH of these modules which is where my confusion came from. The two main modules that make up the Photon are the STM32 chip (the main microcontroller) and the BCM (WiFi chip).

Raspberry pi sleep mode