I can not find the web-page, but I remember reading the BB Black and BB AI Capes were compatible, except something like a different I²C device was used and some GPIO were connected together on BB AI to provide both functions of the BB Black.
With no a fan, the heat sink is too small. The heat sink temperature rises too quickly for older software image to lower the clock speed, before the temperature is too high and the processor (SoC) stops.
This would imply, you need:
- a fan
- a bigger heat-sink
- a lower clock speed
- a newer software image
I bought a 5V 20mm fan, used nylon screws to attach it to heat-sink, soldered some header to the wires, connected the header to +3.3V and GND on P9.
This works well. However, this stops you using capes, fans have a limited life, and you need space for an air flow.
I designed and made my own Fan Cape, I used a 5V 32mm fan.
This works well. However, fans have a limited life, and you need space for an air flow.
I have not had time to investigate this.
I plan to attach a sheet of aluminium 100mm 100mm 5mm to the existing heat-sink or directly to the processor.
The sheet would have cut outs for RJ45, USB, Cape P8, and Cape P9. The first Cape would be spaced away cape through socket-plug without a cape.
However, this will make the package much bigger. A thick metal box could act as heat-sink, if you can get the heat from the processor to the box.
Similar sized system-on-chips run at 200MHz to 500MHz without need of heat-sink.
The speed throttle seems to be a software process, therefore you must be able to set the speed in software.
However, you may not have the speed for your application.
New Software Image
My beagle board came with an image which worked to throttle the clock speed. It asks/suggests you upgrade to the latest image. I, like many others, upgraded the image, only to have a system which overheated in about 30 seconds. Fortunately, this was just enough time to upgrade the image again.
However, you may not have the processor speed for your application.