Asking a very slightly different question here. If using an ESP8266, with esp8266_pwm, how can we define a fully autonomous ESPHome device, that sets the fan speed according to the value of a DHT22 temperature sensor? In other words, keep the speed control completely within the ESPHome device, rather than depending on an HA automation.
Here is my final YAML code. I have omitted MED, HIGH, and MAX template definitions for brevity.
For my use, OFF = 0%, LOW = 25%, MED = 50%, HIGH = 75%, and MAX = 100%.
I’m certain there will be some temperature range tweaking in my future.
switch:
- platform: template
id: fan_speed_off
turn_on_action:
- logger.log:
format: "The temperature sensor reports value %.1f, fans OFF"
args: [ 'id(rack_temp_f).state' ]
- output.turn_off:
id: fan_power
- fan.turn_off:
id: fan_pwm
- platform: template
id: fan_speed_low
turn_on_action:
- logger.log:
format: "The temperature sensor reports value %.1f, fans LOW"
args: [ 'id(rack_temp_f).state' ]
- fan.turn_on:
id: fan_pwm
speed: 25
- output.turn_on:
id: fan_power
temperature:
id: rack_temp_f
name: "Rack Temperature"
unit_of_measurement: "°F"
filters:
lambda: |-
return (x * 1.8) + 32.0;
on_value_range:
- below: 75.0
then:
switch.turn_on: fan_speed_off
- above: 75.1
below: 77.0
then:
switch.turn_on: fan_speed_low
#
# fan_power is a relay switching 12VDC fan power on and off
# pwm_output is a speed control line to the PWM fan
#
output:
- platform: gpio
pin: D5
id: fan_power
- platform: esp8266_pwm
pin: D6
frequency: 20000 Hz
id: pwm_output
#
# The fan object
#
fan:
- platform: speed
id: fan_pwm
name: "Rack Fan PWM"
output: pwm_output
speed_count: 100
restore_mode: ALWAYS_OFF
Could it be the Mosfet you picked? I believe that for current to flow at the Mosfet’s rated capacity you have to turn it on with the right voltage. Many Mosfets still turn on at 3.3V but they are not able to provide the full current the fan may require. By picking a Mosfet that is compatible with 3.3V logic you should be ok, or you need an extra transistor (for example) in between to increase the voltage. Hopefully I relayed this correctly as I researched this a while back.
Edit: I found that the IRF520 requires 10V to be fully (max current) switched on. In my projects I ended up using an SMD mosfet mounted on a small adapter perfboard as I could not find through hole mosfets with enough current that had a 3.3V logic level gate threshold.
Hi fellow @corvy, Did you achieve smooth fan speed control with the slider ?
Or do you only have 3 speeds and fan off ?
I have exactly the same stuff as you i.e. ESP32 with esphome and a board with irf520
Are you able to help me ?
Thank you
The gate barely let’s any current through at 3.3v or 5v. Telling people that the irf520 accepts those logic levels is horrible advice and it’s just wrong. You may be able to get a crappy little fan to work when it uses very little current but when someone needs to conduct multiple amps through that fet they won’t be able to and it’s going to be a nightmare for them troubleshooting it because you told them flat out wrong information.
I‘m having the same issue like you with no speed control if using 20kHz.
I’m using D1 Mini which has ESP8266, 12V fan and mosfet.
I got nearly 12V on my fan regardless of duty cycle.
Because datasheet offers max pwm frequency for esp8266 is 1kHz I‘m thinking to replace it by using esp32.
If I measure directly on pwm pin with my rms multimeter it shows 1,65V at 50% duty cycle and 20kHz so I‘m not sure this is really the problem.
Anyhow I haven’t an oscilloscope so I don‘t know exactly how the waveform looks like.
So did you replace your esp8266 with esp32 and did that fix your problem ?
If you can’t get any speed control, switching to an esp32 isn’t going to change anything. The hardware pwm on the esp32 has a better resolution(technically) and it’s better in certain cases where it’s “noisy” the hardware pwm is better, but for most things you can’t see the differences with the human eye. The fact that you have no speed control suggests you have something wired wrong, the code is wrong, the hardware is wrong. So, your using a mosfet? That’s really helpful. What’s the Vgs? min/max? is it logic level? are you using another transistor as a gate driver? 9 times out of 10 this is because you’re using the wrong fet and the gate can’t be driven by an esp board alone, the 3.3v wont open the gate or will only barely open the gate.
I just made a measurement with a scope and now I can tell you that 20kHz with D1 Mini (ESP 8266EX) is not the problem…
Here you have a measurement directly on the pin where I set up 20kHz pwm (50us) and 50% duty cycle.
what type of fan is this? have you had these fets working anywhere else? There’s lots of knock off components out there. I’m not familiar with that gate driver, have you tried bypassing it? Are you able to drive the load with just the fet and esp board? might be “process of elimination” time.
So for me it looks like the inductive load or the fan itself is the issue here ?!
Should I try another fan or is fast switching with 20kHz impossible with such a simple 2 pin fan ?
Maybe because of the electronic (to commutate the motor wires) on the fan they aren’t made for pwm and allways a constant voltage is needed ?
Good morning,
I use an esp32-s3 to control three 12V 4pin fans(noctua nf-p14s). is it possible to reduce the RPM to almost zero or 100? That would reduce the noise at night.
