ledcWrite() returns successful execution but does not take effect. #11455
Description
Board
ESP32 DEV and a Unknown esp32 board
Device Description
Board only.
Hardware Configuration
Nothing. Only oscilloscope.
Version
v3.1.3
IDE Name
Arduino IDE
Operating System
Windows10
Flash frequency
80Mhz
PSRAM enabled
no
Upload speed
921600
Description
This is a strange problem. When I use v3.1.3, after executing the following code, io5 on the oscilloscope cannot detect any waveform.
#include <Arduino.h>
bool success1 = 0;
bool success2 = 0;
void setup() {
Serial.begin(115200);
ledcAttachChannel(4, 490, 8, 0);
// ledcAttachChannel(5, 50, 10, 2);
ledcAttachChannel(5, 50, 10, 2);
// delay(21);
success1 = ledcWrite(4, 128);
success2 = ledcWrite(5, 75);
Serial.println("success1:" + String(success1) + " success2:" + String(success2));
}
void loop() {
// put your main code here, to run repeatedly:
}Once I change the timer and resolution of io5, io5 cannot output waveforms. But as long as I enable the delay function greater than 20ms in the middle, the code works fine again.
With the same code structure, this problem does not occur when I use version v1.0.6.
#include <Arduino.h>
void setup() {
ledcSetup(0, 490, 8);
ledcAttachPin(4, 0);
ledcSetup(2, 490, 10);
ledcAttachPin(5, 2);
ledcWrite(0, 128);
ledcWrite(2, 75);
}
void loop() {
}Sketch
#include <Arduino.h>
bool success1 = 0;
bool success2 = 0;
void setup() {
Serial.begin(115200);
ledcAttachChannel(4, 490, 8, 0);
// ledcAttachChannel(5, 50, 10, 2);
ledcAttachChannel(5, 50, 10, 2);
delay(21);
success1 = ledcWrite(4, 128);
success2 = ledcWrite(5, 75);
Serial.println("success1:" + String(success1) + " success2:" + String(success2));
}
void loop() {
// put your main code here, to run repeatedly:
}Debug Message
ets Jun 8 2016 00:22:57
rst:0x1 (POWERON_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
mode:DIO, clock div:1
load:0x3fff0030,len:4916
load:0x40078000,len:16492
load:0x40080400,len:4
load:0x40080404,len:3524
entry 0x400805b8
[ 1][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RX (2) successfully set to 0x400d40f4
[ 12][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_TX (3) successfully set to 0x400d40c4
[ 26][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_CTS (4) successfully set to 0x400d4094
[ 39][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RTS (5) successfully set to 0x400d4064
[ 53][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RX (2) successfully set to 0x400d40f4
[ 66][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_TX (3) successfully set to 0x400d40c4
[ 80][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_CTS (4) successfully set to 0x400d4094
[ 93][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RTS (5) successfully set to 0x400d4064
[ 107][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RX (2) successfully set to 0x400d40f4
[ 120][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_TX (3) successfully set to 0x400d40c4
[ 133][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_CTS (4) successfully set to 0x400d4094
[ 147][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type UART_RTS (5) successfully set to 0x400d4064
[ 163][D][esp32-hal-cpu.c:263] setCpuFrequencyMhz(): PLL: 480 / 2 = 240 Mhz, APB: 80000000 Hz
[ 176][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 3 successfully set to type UART_RX (2) with bus 0x3ffbdb60
[ 187][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 1 successfully set to type UART_TX (3) with bus 0x3ffbdb60
=========== Before Setup Start ===========
Chip Info:
------------------------------------------
Model : ESP32
Package : D0WD-Q6
Revision : 1.00
Cores : 2
CPU Frequency : 240 MHz
XTAL Frequency : 40 MHz
Features Bitfield : 0x00000032
Embedded Flash : No
Embedded PSRAM : No
2.4GHz WiFi : Yes
Classic BT : Yes
BT Low Energy : Yes
IEEE 802.15.4 : No
------------------------------------------
INTERNAL Memory Info:
------------------------------------------
Total Size : 379844 B ( 370.9 KB)
Free Bytes : 340444 B ( 332.5 KB)
Allocated Bytes : 32212 B ( 31.5 KB)
Minimum Free Bytes: 334904 B ( 327.1 KB)
Largest Free Block: 110580 B ( 108.0 KB)
------------------------------------------
Flash Info:
------------------------------------------
Chip Size : 4194304 B (4 MB)
Block Size : 65536 B ( 64.0 KB)
Sector Size : 4096 B ( 4.0 KB)
Page Size : 256 B ( 0.2 KB)
Bus Speed : 80 MHz
Bus Mode : QIO
------------------------------------------
Partitions Info:
------------------------------------------
nvs : addr: 0x00009000, size: 20.0 KB, type: DATA, subtype: NVS
otadata : addr: 0x0000E000, size: 8.0 KB, type: DATA, subtype: OTA
app0 : addr: 0x00010000, size: 1280.0 KB, type: APP, subtype: OTA_0
app1 : addr: 0x00150000, size: 1280.0 KB, type: APP, subtype: OTA_1
spiffs : addr: 0x00290000, size: 1408.0 KB, type: DATA, subtype: SPIFFS
coredump : addr: 0x003F0000, size: 64.0 KB, type: DATA, subtype: COREDUMP
------------------------------------------
Software Info:
------------------------------------------
Compile Date/Time : Jun 10 2025 20:29:37
Compile Host OS : windows
ESP-IDF Version : v5.3.2-584-g489d7a2b3a-dirty
Arduino Version : 3.1.3
------------------------------------------
Board Info:
------------------------------------------
Arduino Board : ESP32_DEV
Arduino Variant : esp32
Arduino FQBN : esp32:esp32:esp32:JTAGAdapter=default,PSRAM=disabled,PartitionScheme=default,CPUFreq=240,FlashMode=qio,FlashFreq=80,FlashSize=4M,UploadSpeed=921600,LoopCore=1,EventsCore=1,DebugLevel=verbose,EraseFlash=none,ZigbeeMode=default
============ Before Setup End ============
[ 697][V][esp32-hal-uart.c:421] uartBegin(): UART0 baud(115200) Mode(800001c) rxPin(3) txPin(1)
[ 706][V][esp32-hal-uart.c:510] uartBegin(): UART0 not installed. Starting installation
[ 716][V][esp32-hal-uart.c:575] uartBegin(): UART0 initialization done.
[ 731][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type LEDC (12) successfully set to 0x400d1964
[ 743][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 4 successfully set to type LEDC (12) with bus 0x3ffb8df0
[ 753][I][esp32-hal-ledc.c:166] ledcAttachChannel(): LEDC attached to pin 4 (channel 0, resolution 8)
[ 762][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type LEDC (12) successfully set to 0x400d1964
[ 773][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 5 successfully set to type LEDC (12) with bus 0x3ffb8e10
[ 784][I][esp32-hal-ledc.c:166] ledcAttachChannel(): LEDC attached to pin 5 (channel 2, resolution 10)
success1:1 success2:1
=========== After Setup Start ============
INTERNAL Memory Info:
------------------------------------------
Total Size : 379844 B ( 370.9 KB)
Free Bytes : 337836 B ( 329.9 KB)
Allocated Bytes : 34468 B ( 33.7 KB)
Minimum Free Bytes: 332160 B ( 324.4 KB)
Largest Free Block: 110580 B ( 108.0 KB)
------------------------------------------
GPIO Info:
------------------------------------------
GPIO : BUS_TYPE[bus/unit][chan]
--------------------------------------
1 : UART_TX[0]
3 : UART_RX[0]
4 : LEDC[0][0]
5 : LEDC[0][2]
============ After Setup End =============
Other Steps to Reproduce
No response
I have checked existing issues, online documentation and the Troubleshooting Guide
- I confirm I have checked existing issues, online documentation and Troubleshooting guide.
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P-R-O-C-H-Y commentedon Jun 10, 2025
Hi @zhengyangliu, can you please retest the "master" or latest 3.2.0 version? Thanks
zhengyangliu commentedon Jun 10, 2025
I tried 3.2.0 and the problem still exists. Now it won't work if I change it to the same resolution. It will only work if I add a delay.
P-R-O-C-H-Y commentedon Jun 10, 2025
Thanks for re-testing. I will give it a try tomorrow and keep you updated about the issue.
zhengyangliu commentedon Jun 10, 2025
I also tested esp32s3 and it didn't have this problem.
Looking forward to your work.
P-R-O-C-H-Y commentedon Jun 11, 2025
@zhengyangliu I am still investigating where the problem is, but I found out if you use channels from different LEDC groups the error does not occur.
P-R-O-C-H-Y commentedon Jun 11, 2025
I was able to reproduce the issue using ESP-IDF directly. I will report it to them.
P-R-O-C-H-Y commentedon Jun 11, 2025
It also work if you use 2 LOW Speed channels -> 8-15. The issue only appears if 23 HIGH speed channels are used (0-7).
zhengyangliu commentedon Jun 11, 2025
@P-R-O-C-H-Y Thank you very much for your additional testing work. This should make it easier to locate this bug. It looks very much like a hardware bug of the chip, but I can be sure that I cannot trigger this problem using the 1.x core.
Because I am not very familiar with the register configuration of esp32, I can't find the problem code by myself. I really hope this bug can be fixed soon.
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