FeatherS3 Hard Crash When Setting RTC

[sco1]

CircuitPython version and board name

Adafruit CircuitPython 10.0.3 on 2025-10-17; FeatherS3 with ESP32S3

Code/REPL

import rtc
import time
from adafruit_featherwing import tft_featherwing_35


r = rtc.RTC()
r.datetime = time.struct_time((2019, 5, 29, 15, 14, 15, 0, -1, -1))
print("set RTC")

print("pre-init")
fw = tft_featherwing_35.TFTFeatherWing35V2()
print("post-init")

Behavior

Auto-reload is off.
Running in safe mode! Not running saved code.

You are in safe mode because:
CircuitPython core code crashed hard. Whoops!
Hard fault: memory access or instruction error.
Please file an issue with your program at github.com/adafruit/circuitpython/issues.
Press reset to exit safe mode.

Description

I've been working on bumping my Skyportal lib from CP 9.2.2 to 10.0.3 and have run into this hard fault during initialization of the device. I believe I have narrowed it down to the initialization step where the RTC is set from a timestamp provided by AIO, but seems to be reproduced with the simpler example above.

Other hopefully relevant information:

• FeatherS3 + FeatherWing V2 w/TSC2007
• Board updated to 10.0.3 using the web installer
• Libraries sourced from the version 10.x bundles

Additional information

No response

[dhalbert]

If you don't do fw = tft_featherwing_35.TFTFeatherWing35V2() does it still go into safe mode?

[sco1]

I don't think I have it narrowed down as well as I thought. On a freshly flashed device my sample code does not put the device into safe mode, but the behavior returns once I try running my actual library.

I'm going to close this for now until I can come up with a minimal reproduction that works from scratch on a fresh flash. My apologies for the noise.

[sco1]

Finally had some time to poke at this some more. I've come up with a new example that I apologize is not quite so minimal but it seems to consistently crash a freshly flashed device. I'm not sure if it's all needed but wanted to start by recreating what is being run by the project.

Not instantiating tft_featherwing_35.TFTFeatherWing35V2() appears to prevent the crash.

I can't tell if it's a red herring or not but it seems like if I run this while connected to the serial port it crashes hard and no longer even shows up as a drive in Windows, but if I am not connected then it reboots into safe mode.

import adafruit_requests
import rtc
import socketpool
import ssl
import time
import wifi
from adafruit_featherwing import tft_featherwing_35
from collections import OrderedDict

from secrets import secrets


TIME_SERVICE = f"https://io.adafruit.com/api/v2/{secrets['aio_username']}/integrations/time/strftime"
TIME_SERVICE_FORMAT = r"%Y-%m-%d %H:%M:%S.%L %j %u %z %Z"


def build_url(base: str, params: dict[str, t.Any]) -> str:
    param_str = "&".join(f"{k}={v}" for k, v in params.items())
    return f"{base}?{param_str}"


def urlencode(url: str) -> str:
    encoded_chars = []
    for c in url:
        if any((c.isalpha(), c.isdigit(), (c in ("-", ".")))):
            encoded_chars.append(c)
        else:
            encoded_chars.append(f"%{ord(c):02X}")

    return "".join(encoded_chars)

def struct_time_from_timestr(timestr):
    comps = timestr.split()

    year, month, day = (int(n) for n in comps[0].split("-"))
    year_day, week_day = int(comps[2]), int(comps[3])

    time_str = comps[1].split(".")[0]
    hour, minute, second = (int(n) for n in time_str.split(":"))
    is_dst = -1

    return time.struct_time((year, month, day, hour, minute, second, week_day, year_day, is_dst))


wifi.radio.connect(secrets["ssid"], secrets["password"])
print("Wifi connected")

pool = socketpool.SocketPool(wifi.radio)
session = adafruit_requests.Session(pool, ssl.create_default_context())
print("Session created")

adaIO_params = OrderedDict(
    [
        ("x-aio-key", secrets["aio_key"]),
        ("tz", "America/New_York"),
        ("fmt", urlencode(TIME_SERVICE_FORMAT)),
    ]
)
query_url = build_url(TIME_SERVICE, adaIO_params)

print(f"Querying local time for 'America/New_York'")
resp = session.get(query_url)
timestr = resp.text
print("Obtained time from Ada IO")

new_time = struct_time_from_timestr(timestr)
r = rtc.RTC()
r.datetime = new_time
print("RTC Set")

fw = tft_featherwing_35.TFTFeatherWing35V2()
print("Featherwing init")

The terminal output:

Adafruit CircuitPython 10.0.3 on 2025-10-17; FeatherS3 with ESP32S3
>>> 
soft reboot

Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
Hello World!
Wifi connected
Session created
Querying local time for 'America/New_York'
Obtained time from Ada IO
RTC Set
Featherwing init

Code done running.

After this the device & serial connections stop responding.

For context, I originally developed my project for the PyPortal (hence Skyportal), but moved to the FeatherS3 to alleviate RAM constraints a bit, and also because it's fun to tinker. Because the Feather doesn't have some of the helper functionality that's baked into the PyPortal instance (e.g. web session, touchscreen, etc.), I made a compatibility layer so the two could share the main bulk of the project code.