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OBK PWMFrequency Command Issue on Pin 17, Frequency Stuck at 2kHz

omelchuk890 993 8
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  • PWMFrequency appears fixed at 2 kHz on BL602

    #1 21688382
    omelchuk890
    Level 11  
    Posts: 70
    Rate: 10
    I needed to make WiFi control for a room heater.
    For this, I decided to use a ready-made WiFi relay module from Aliexpress, having slightly modified it.
    I planned to add a 18b20 sensor, and an output to a solid-state relay in slow PWM mode, 5-10s(0.2-0.1Hz).
    Let's leave the script out of the equation for now, and run into the main thing - the PWMFrequency command does not work at all - no matter what argument I set, 50, 100, 0.5, the PWM pin frequency remains 1.99998 kHz
    The duty cycle is adjusted by a slider via the web

    Maybe I'm doing something wrong?
    What is the range of PWM frequency adjustment?
    You can probably make a loop in the script and use variable delays to switch the pin, but this is somehow not Feng Shui :)
    Chipset: BL602
    pin 17 - PWM
    /autoexec.bat
    PWMFrequency 25
    If there are any difficulties, I will have to write everything again through the Arduino IDE on the ESP32C3 - but there will be no beautiful and convenient web...

    P.S. !!! The command works on the BK7231! But the minimum frequency is 1Hz...
    W pełni konfigurowalna automatyzacja domu - prezentacja Fox Wi-Fi Quad Input [sponsorowany]
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  • Source code limits PWM frequency to 2 kHz minimum

    #2 21689148
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14770
    Help: 659
    Rate: 12913
    I don't remember now, but we have a limit for that in source code:
    Code: C / C++
    Log in, to see the code

    I can make PR with removed check so you can see if it works
    Helpful post? Buy me a coffee.
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  • Suggesting a different PWM clock divider

    #4 21689166
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14770
    Help: 659
    Rate: 12913
    Maybe it could with different clk divider?
    Code: C / C++
    Log in, to see the code
    Helpful post? Buy me a coffee.
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  • Script workaround for integer PWM frequency control

    #5 21689211
    insmod
    Level 31  
    Posts: 1432
    Help: 168
    Rate: 455
    >>21689166
    Possible. And alternative is to use a different clk source. BL_PWM_CLK is defined to BL_PWM_XTAL_CLK which is defined to 40000000.
    If PWM_CLK_BCLK is to be used, BL_PWM_CLK would have to be 80000000. But that way minimum pwm frequency is likely to be 4000.
    Next is PWM_CLK_32K. BL_PWM_CLK is to be 32768? That way with 0 divider max frequency is 655hz? Minimum is 2hz?

    I think a script would be easier. Especially since frequency is a integer, not a float.
  • #6 21689346
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14770
    Help: 659
    Rate: 12913
    I can easily make a custom driver for that. Either with pin role (then maybe in obk core?), or configurable via autoexec.bat

    But maybe better a driver configurable in autoexec.bat

    Drive would use quick tick of OBK so it wouldn't have a great precision, but for lower frequencies it would be ok.

    How would setup look like? @omelchuk890 Specify pin, duty in % and frequency?
    Helpful post? Buy me a coffee.

  • Custom PWM heater control script with 18B20 and SSR

    #7 21691981
    omelchuk890
    Level 11  
    Posts: 70
    Rate: 10
    >>21689346
    Now I use, as a test, the LED on the board - it is more visual.
    The frequency for the heater, or rather the PWM period, will be about 5 seconds.
    For this application, as a test, I plan to use the P regulator.
    This will be an additional module to a conventional heater, which in the absence of people will maintain the required minimum temperature, and before arrival remotely switch to the desired one. On the heater itself there is a regulator (native thermostat and thermal fuse), which will be set to maximum, so overheating does not threaten.
    I plan to implement it on 18B20 and SSR RM1A48D25.
    Another idea is to turn on and off the relay, 16A, when the SSR is off - for less sparking on the contacts.
    Now I tested such a script. There is a misunderstanding with the transitions, a feeling that in some places it works incorrectly. I have not added a sensor yet. The chip is now 7231N
    Code: text Expand Select all Copy to clipboard
    Powersave 1
// chanel 5 this time power on pwm
if $CH5==0 then setChannel 5 50
// chanel 5 this time power off pwm
setChannel 6 100
// chanel 7- its koeff from second
setChannel 7 50
// chanel 6 this time power off pwm
//if $CH6==0 then setChannel 5 0
setChannelType 5 TextField
// set label
setChannelLabel 5 Turn_On_Time
SetChannelVisible 2 0
SetChannelPrivate 2 1

mainLoop:

if $CH1==1 then "goto pwmOn" else "goto pwmOff"

// run pwm
pwmOn:
if $CH5>99 then backlog setChannel 5 100; setChannel 2 1; delay_s 1
if $CH5<1 then backlog setChannel 5 0; setChannel 2 0; delay_s 1
//if $CH5>100 then backlog setChannel 5 100; setChannel 2 1; delay_s 1;"goto mainLoop"  <- no run
//if $CH5<0 then backlog setChannel 5 0; setChannel 2 0; delay_s 1;"goto mainLoop"  <- no run
//if $CH5==0||$CH5==100 then "goto mainLoop"
setChannel 6 100-$CH5
setChannel 2 0
delay_ms $CH6*$CH7
if $CH5>0 then setChannel 2 $CH1
delay_ms $CH5*$CH7
goto mainLoop

pwmOff:
setChannel 2 0
delay_s 1
goto mainLoop

    It's still inexpensive here, $3 each, I bought new modules, maybe if I can flash them, I'll do it on them.
    OBK PWMFrequency Command Issue on Pin 17, Frequency Stuck at 2kHz
    OBK PWMFrequency Command Issue on Pin 17, Frequency Stuck at 2kHz

  • Timer-based PWM with hidden status channel

    #9 21692095
    omelchuk890
    Level 11  
    Posts: 70
    Rate: 10
    The CHL at the end of the marking is confusing.
    If it is really 7238, then I think it is good, your team has implemented their support.
    Regarding the topic - I had to "hide" the channel, otherwise there is a constant sending of the status.
    Considering that the bit depth is not needed to be large, I think 100-200 is enough, and it is possible to implement this on timers.
    Primary check, for minimum/maximum - if true, then we do not start the counter, we simply set the output to the desired state.
    otherwise
    The counter is maximum, we start from low.
    A call, for example, every 40 ms, these are two periods of network voltage, counter check, decrement.
    if the desired value is reached, the output is in a high state, we count to 0, the procedure is reset.

    I don't use tasmota, esphome (there seems to be a slow PWM) and other stuff - only hardcore in the form of mqtt and node-red :) Also a voice assistant from Yandex via node, and Arduino IDE for peripherals
    And devices that thanks to you were flashed and linked to my zoo :)
    I really like your web!!!
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Topic summary

LABEL_AI_GENERATED
The discussion centers on a BL602-based WiFi relay module where the PWMFrequency command on pin 17 appears stuck at about 2 kHz regardless of the requested value. Source code excerpts show a hard lower limit of 2000 Hz in the PWM initialization path, and another reference confirms the same 2 kHz to 800 kHz constraint in the BL602 PWM driver. Possible workarounds discussed include changing the PWM clock source/divider, but the frequency range remains limited by the driver implementation. For the intended heater control use case, a slow PWM period of about 5 seconds is needed, so a custom driver or timer-based software PWM via autoexec.bat was proposed as a more suitable solution. Later messages mention testing on a different chip, hiding the channel to reduce status traffic, and considering a low-resolution timer-driven control scheme for SSR and relay switching.
AI summary based on the discussion. May contain errors.
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