iw2nke

Usually to run a fan at the max speed reduce the life and the MTBF. Moreover in our case the goal is to stay below a reference temperature. In winter with low temperatures probably the required forced airflow is significantly lower. Last point is the acoustic noise generated by the fans.
The fan I prefer to use has a range in power consumption from 0.5 W up to 5 W, a lot of money for a 24h/365d service.

Here some preliminary results.

The measurement conditions are Kiwi running at 1 GHz, with 14 channels used to carry the IQ stream to a wsprdaemon client.

The ambient temperature is 20° C, without any relevant airflow (artificial or natural). The board is in an open environment, without a box as you can see this photo.


For the cooling system a NMB fan model 04028DA-12R-AUF has been used: the supply voltage is 12 V and it has auxiliary wires for PWM control and tachometer.
It is usually selected in telecom carrier grade equipment. The tachometer is useful to report reduced efficiency during the lifetime or as signaling method in case of blocking.
Each level of speed has been maintained for 60 minutes to assure that not only the transition has been recorded but that a stable point was reached.

The conducted test had the purpose to show the impact of the PWM control versus temperature of the BB AI and power consumption.

A first coarse measurement starting from an high speed mode and then lowering shows that the major step is within a range comprised between 10% and 30%.


Then the fine measurement with 1% steps


and a zoom in the most promising zone as stability target: 48° C ± 2°


The PWM control is based on the AM5729 internal block and the tachometer is performed with gpiod library using the pin P8.35
To enable PWM in the P8.36 the dts shall be modified including the following code

&epwmss0 {
 status = "okay";
};
&ehrpwm0 {
 status = "okay";
 pinctrl-names = "default";
 pinctrl-0 = <&ehrpwm0_pins>;
};
&dra7_pmx_core {
 ehrpwm0_pins: ehrpwm0 {
  pinctrl-single,pins = <
   DRA7XX_CORE_IOPAD( 0x3568, PIN_OUTPUT| MUX_MODE10 ) // P8.36b
  >;
 };
};

To avoid conflicts on the same pin it is also required to modify the setting for this register under the cape_pins_kiwi group:
DRA7XX_CORE_IOPAD(0x3604, MUX_MODE15) // D7 P8.36a
The row inside the same group referring to the P8.36b must be removed.

I hope John can accept this modification in his code: these pins are unused in the BBAI when hosting the Kiwi board.

The next step is to implement the control, with alarms and controlled shutdown in case of fault of the fan, and to place all the elements inside a 14TE Eurocard cassette.

73,

GL

Here some preliminary results.

The measurement conditions are Kiwi running at 1 GHz, with 14 channels used to carry the IQ stream to a wsprdaemon client.

The ambient temperature is 20° C, without any relevant airflow (artificial or natural). The board is in an open environment, without a box as you can see this photo.


For the cooling system a NMB fan model 04028DA-12R-AUF has been used: the supply voltage is 12 V and it has auxiliary wires for PWM control and tachometer.
It is usually selected in telecom carrier grade equipment. The tachometer is useful to report reduced efficiency during the lifetime or as signaling method in case of blocking.
Each level of speed has been maintained for 60 minutes to assure that not only the transition has been recorded but that a stable point was reached.

The conducted test had the purpose to show the impact of the PWM control versus temperature of the BB AI and power consumption.

A first coarse measurement starting from an high speed mode and then lowering shows that the major step is within a range comprised between 10% and 30%.


Then the fine measurement with 1% steps


and a zoom in the most promising zone as stability target: 48° C ± 2°


The PWM control is based on the AM5729 internal block and the tachometer is performed with gpiod library using the pin P8.35
To enable PWM in the P8.36 the dts shall be modified including the following code

&epwmss0 {
 status = "okay";
};
&ehrpwm0 {
 status = "okay";
 pinctrl-names = "default";
 pinctrl-0 = <&ehrpwm0_pins>;
};
&dra7_pmx_core {
 ehrpwm0_pins: ehrpwm0 {
  pinctrl-single,pins = <
   DRA7XX_CORE_IOPAD( 0x3568, PIN_OUTPUT| MUX_MODE10 ) // P8.36b
  >;
 };
};

To avoid conflicts on the same pin it is also required to modify the setting for this register under the cape_pins_kiwi group:
DRA7XX_CORE_IOPAD(0x3604, MUX_MODE15) // D7 P8.36a
The row inside the same group referring to the P8.36b must be removed.

I hope John can accept this modification in his code: these pins are unused in the BBAI when hosting the Kiwi board.

The next step is to implement the control, with alarms and controlled shutdown in case of fault of the fan, and to place all the elements inside a 14TE Eurocard cassette.

73,

GL

Here some preliminary results.

The measurement conditions are Kiwi running at 1 GHz, with 14 channels used to carry the IQ stream to a wsprdaemon client.

The ambient temperature is 20° C, without any relevant airflow (artificial or natural). The board is in an open environment, without a box as you can see this photo.


For the cooling system a NMB fan model 04028DA-12R-AUF has been used: the supply voltage is 12 V and it has auxiliary wires for PWM control and tachometer.
It is usually selected in telecom carrier grade equipment. The tachometer is useful to report reduced efficiency during the lifetime or as signaling method in case of blocking.
Each level of speed has been maintained for 60 minutes to assure that not only the transition has been recorded but that a stable point was reached.

The conducted test had the purpose to show the impact of the PWM control versus temperature of the BB AI and power consumption.

A first coarse measurement starting from an high speed mode and then lowering shows that the major step is within a range comprised between 10% and 30%.


Then the fine measurement with 1% steps


and a zoom in the most promising zone as stability target: 48° C ± 2°


The PWM control is based on the AM5729 internal block and the tachometer is performed with gpiod library using the pin P8.35
To enable PWM in the P8.36 the dts shall be modified including the following code

&epwmss0 {
 status = "okay";
};
&ehrpwm0 {
 status = "okay";
 pinctrl-names = "default";
 pinctrl-0 = <&ehrpwm0_pins>;
};
&dra7_pmx_core {
 ehrpwm0_pins: ehrpwm0 {
  pinctrl-single,pins = <
   DRA7XX_CORE_IOPAD( 0x3568, PIN_OUTPUT| MUX_MODE10 ) // P8.36b
  >;
 };
};

To avoid conflicts on the same pin it is also required to modify the setting for this register under the cape_pins_kiwi group:
DRA7XX_CORE_IOPAD(0x3604, MUX_MODE15) // D7 P8.36a
The row inside the same group referring to the P8.36b must be removed.

I hope John can accept this modification in his code: these pins are unused in the BBAI when hosting the Kiwi board.

The next step is to implement the control, with alarms and controlled shutdown in case of fault of the fan, and to place all the elements inside a 14TE Eurocard cassette.

73,

GL