The Pycom Deep Sleep Problem

For anyone that has been running into issues trying to get their Pycom WiPy, LoPy, or SiPy ESP32-based boards to enter deep sleep mode, the company has now tracked down the issue to design problems with the hardware of the boards themselves.

The Pycom WiPy 2.0 board. (📷: Alasdair Allan)

Issues around deep sleep with the boards started being raised in the company’s support forums more than a month ago after support for the mode was finally added to the Espressif IDF for the ESP32 chip.

The deep sleep issues with the Pycom boards has two different root causes. The first has to do with the DC-DC regulator used on the board.

This has a fairly easy work around; powering the board via the 3V pin using a supply that is able to deliver at least 400mA drops the deep sleep current to around 2.5mA. Unfortunately, the second design issue is a bit more problematic.

To fix this issue Pycom has gone ahead and designed a deep sleep shield that needs to be fitted to the module which will take care of powering down the module when a deep sleep command is sent. With the shield in place current consumption during deep sleep is between 7μA and 10μA depending on the wake source.

The new add-on board should be detected by the module during startup and will resolve both hardware issues, also allowing you to power the module normally.

Daniel Campora, the Pycom CTO, performing a live test of the L01 (LoPy) OEM module in deep sleep mode. (🎥: Pycom)

The company says that the design issues leading to the deep sleep problems do not exist in any of their other developer boards such such as their long anticipated FiPy board — which supports WiFi, BLE, cellular LTE-CAT M1/NB1, LoRa, and Sigfox—which should be shipping to Kickstarter backers soon, or their OEM modules.

Pycom has also committed to redesigning the WiPy, LoPy, and SiPy modules over the next few months in order to remove this deep sleep issue.

Full details of the problems can be found on the company’s support forums, along with instructions on how to order your free deep sleep shield.



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