QUERY · ISSUE

lightsleep results in machine reset on ESP32

openby jdstroyopened 2020-03-20updated 2020-03-23

port-esp32

Hello,

I'm running this version of MicroPython on ESP32:

MicroPython v1.12-262-g19ea30bdd on 2020-03-20; ESP32 module with ESP32

And I'm observing unexpected behavior with machine.lightsleep().

I would expect the following program code:

import machine
import time
while True:
    machine.lightsleep(10)

to behave in the same way as:

import machine
import time
while True:
    time.sleep_ms(10)

However, the prior always results in a WDT reset on my platform:

>>> import machine;
>>> while True:
...     machine.lightsleep(10);
...
...
...
ets Jun  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00

This seems like a bug in machine.lightsleep(), as I can reproduce this with any value given to lightsleep, and even performing consecutive machine.lightsleep(100); calls directly without a loop.

CANDIDATE · ISSUE

PICO machine.lightsleep resets registers SLEEP_EN0 and SLEEP_EN1

closedby cpottle9opened 2024-12-29updated 2025-02-07

bugport-rp2

Port, board and/or hardware

rp2

MicroPython version

MicroPython v1.24.1 on 2024-11-29; Raspberry Pi Pico W with RP2040

Reproduction

I reproduced the problem with thonny running on a RPI 4 (not important).

I using code from my github project project RP2-PowerControl:

Download power_ctrl_2040.py and power_ctrl_abstract.py to the pico W.
Run the following code:

from machine import lightsleep
from power_ctrl_2040 import PowerCtrl
pwr = PowerCtrl()

print(pwr) # displays default values for WAKE_EN0, WAKE_EN1, SLEEP_EN0, and SLEEP_EN1

pwr.disable_while_sleeping(
    pwr.EN1_CLK_SYS_UART1, 
    pwr.EN1_CLK_PERI_UART1, 
    pwr.EN0_CLK_SYS_SRAM3,
    pwr.EN0_CLK_SYS_SRAM2
)
print(pwr) # note SLEEP_EN0 and SLEEP_EN1 changed.

lightsleep(100)

print(pwr) # back to default values

Output I see is:

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: FFFFFFFF sleep_en1: 00007FFF

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: 3FFFFFFF sleep_en1: 00007CFF

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: FFFFFFFF sleep_en1: 00007FFF

The third time pwr is printed should be the same as the second time.

Expected behaviour

The problem does not exist on earlier versions but unfortunately can't be reproduced because lightsleep breaks USB.

I coded the fix off the latest micropython. The version information for my build is:
MicroPython c73204128-dirty on 2024-12-29; Raspberry Pi Pico W with RP2040

Correct output is:

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: FFFFFFFF sleep_en1: 00007FFF

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: 3FFFFFFF sleep_en1: 00007CFF

PowerCtrl for RP2040
wake_en0:  FFFFFFFF wake_en1:  00007FFF
sleep_en0: 3FFFFFFF sleep_en1: 00007CFF

Observed behaviour

The code in my project RP2-PowerControl is intended to reduce power consumed when the RP2040 (or RP2350) are sleeping for any reason.
Specifically, both CPU cores need to be asleep and no DMA active.

This includes calls to time.sleep_ms() for instance.
But also includes all cases where either __WFI() or __WFE() are called.

Because of this defect calling machine.lightsleep() resets SLEEP_EN0 and SLEEP_EN1 to their power on values.
The expected power savings will go away.

Additional Information

The problem was introduced in commit d1423ef.

Prior to that commit machine.lightsleep save the current value of SLEEP_EN0 and SLEEP_EN1 on entry and restore them on exit.

As mentioned, I have the fix coded and will submit a pull request shortly.

Code of Conduct

Yes, I agree