QUERY · ISSUE

ESP32_C3： timer_group: timer_init(271): HW TIMER NUM ERROR

openby iBoundaryopened 2022-10-19updated 2026-03-19

bugport-esp32

from machine import*
tim = Timer(-1)
tim.init(period=1000,callback = lambda t:print('rtos'))
E (6078630) timer_group: timer_init(271): HW TIMER NUM ERROR
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
OSError: (-258, 'ESP_ERR_INVALID_ARG')

I found out that virtual timer is not available in ESP32_C3 chip.

CANDIDATE · PULL REQUEST

esp32/machine_timer.c: Restrict timer numbers for ESP32C3 to 0 and 1.

mergedby robert-hhopened 2024-04-03updated 2024-07-23

port-esp32

The ESP32C3 has only two timers in one group. Previously trying to use timer 3 caused a core dump.

Addresses the issue uncovered in discussion #14235.

Assessment

S Sonnet · high

Both concern ESP32C3 timer hardware constraints in machine_timer.c, but they target different problems. The query reports that Timer(-1) (virtual/RTOS-based timer) fails on ESP32C3 with ESP_ERR_INVALID_ARG because virtual timers are unsupported on that chip. The candidate PR restricts hardware timer indices to 0 and 1 (preventing core dumps when timer 3 is accessed) — it does not address the virtual timer (-1) code path at all. Same file, same chip, different root causes.

Suggested action

Keep the issue open. The candidate PR partially improves timer validation on ESP32C3 but does not fix the virtual timer (-1) failure. A separate fix is needed to either detect ESP32C3's lack of virtual timer support and raise a clear Python-level error, or explicitly document/guard against Timer(-1) on that chip variant.

ESP32_C3： timer_group: timer_init(271): HW TIMER NUM ERROR

esp32/machine_timer.c: Restrict timer numbers for ESP32C3 to 0 and 1.

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