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| en:iot-open:practical:hardware:sut:esp32:emb1a_1 [2024/04/09 12:52] – [Steps] pczekalski | en:iot-open:practical:hardware:sut:esp32:emb1a_1 [2024/04/09 12:55] (current) – [FAQ] pczekalski |
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| **The fan rotates itself. Why?**: It is connected via the MOS FET transistor that tends to saturate when the GPIO (35) is not controlling it. So, to ensure the fan is stopped, bind a PWM channel to it and force the duty cycle set to 0. | **The fan rotates itself. Why?**: It is connected via the MOS FET transistor that tends to saturate when the GPIO (35) is not controlling it. So, to ensure the fan is stopped, bind a PWM channel to it and force the duty cycle set to 0. |
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| **The fan is not rotating?**: Besides possible configuration and programming errors, it is essential to understand that setting duty cycle, e.g. to 1, won't start spinning: a minimum value (a threshold) causes rotation. Moreover, the relation between rotation speed, air pressure and duty cycle controlling the fan is not linear. | **The fan is not rotating?**: Besides possible configuration and programming errors, it is essential to understand that setting duty cycle, e.g. to 1, won't start spinning: a minimum value (a threshold) causes rotation. Moreover, the relation between rotation speed, air pressure and duty cycle controlling the fan is not linear. You may also be a victim of the common coding mistake of using a GPIO number instead of the channel number (first parameter) in the ''ledcWrite'' function: use the PWM channel number! |
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| **What is the maximum number of channels?**: the MCU we use here is ESP32-S3, so it has 8 PWM channels. You can use timers and software implementation of the PWM signal if you need more, but that is a bit tricky and may not be as precise as hardware PWM implementation. | **What is the maximum number of channels?**: the MCU we use here is ESP32-S3, so it has 8 PWM channels. You can use timers and software implementation of the PWM signal if you need more, but that is a bit tricky and may not be as precise as hardware PWM implementation. |
