4 ms·

The spec limits ambient temperature to -44–55°C. As the low temperate range of the regular Pis was the major limiting factor for use in industrial applications

The spec limits ambient temperature to -44–55°C. As the low temperate range of the regular Pis was the major limiting factor for use in industrial applications (0–50), is there some module that goes further? Think of devices deployed in a street cabinet in summer heat f.ex., those have to endure much higher temps.

l1k 7y ago
We use the Raspberry Pi Compute Module, not the regular Raspberry Pi. The Compute Module is basically a SO-DIMM slot with the BCM2835 or BCM2837 SoC plus eMMC and LP-DDR2 RAM. The Compute Module is spec'ed at -25 to 80°C, versus 0 to 50°C on the regular Raspberry Pi. We did extensive testing in the climate chamber and felt that going down to -40°C is safe. The BCM2837 normally runs at 1200 MHz and the firmware starts downclocking when the core temperature exceeds 80°C. Once it reaches 85°C, the frequency is reduced to 600 MHz. It will be further reduced to 300 MHz when going beyond that. In our testing we found that the CPU is eventually halted when it becomes too hot, but can be rebooted without any issues once it has cooled down. If you know that ambient temperature regularly exceeds 55°C, it may be necessary to install cooling in the cabinet together with the RevPi. Since you're mentioning street cabinets, our customer Nicolai Buchwitz of Enda KG regularly installs our products in street cabinets for monitoring of hydrogen fuelling stations: https://twitter.com/NicolaiBuchwitz/status/1112727820042727424 https://twitter.com/NicolaiBuchwitz/status/11127278200427274... https://youtu.be/4iaInDiEiQg?t=338 https://youtu.be/4iaInDiEiQg?t=338
- cfstras 7y ago
  Awesome, thanks for the info! Does the hardware watchdog work when halted because of over-temp?
  - l1k 7y ago
    You mean the watchdog integrated into the BCM2835? That's a good question, we haven't tested that yet, but I've added it to the todo list now. One particular product in the Revolution Pi lineup called "Connect" has an additional hardware watchdog which is also capable of resetting attached devices via a relay. That one works even when the BCM2835 has locked up completely. However, the CPU needs to have cooled down a bit to reboot successfully.

l1k 7y ago

We use the Raspberry Pi Compute Module, not the regular Raspberry Pi. The Compute Module is basically a SO-DIMM slot with the BCM2835 or BCM2837 SoC plus eMMC and LP-DDR2 RAM. The Compute Module is spec'ed at -25 to 80°C, versus 0 to 50°C on the regular Raspberry Pi. We did extensive testing in the climate chamber and felt that going down to -40°C is safe. The BCM2837 normally runs at 1200 MHz and the firmware starts downclocking when the core temperature exceeds 80°C. Once it reaches 85°C, the frequency is reduced to 600 MHz. It will be further reduced to 300 MHz when going beyond that. In our testing we found that the CPU is eventually halted when it becomes too hot, but can be rebooted without any issues once it has cooled down. If you know that ambient temperature regularly exceeds 55°C, it may be necessary to install cooling in the cabinet together with the RevPi. Since you're mentioning street cabinets, our customer Nicolai Buchwitz of Enda KG regularly installs our products in street cabinets for monitoring of hydrogen fuelling stations: https://twitter.com/NicolaiBuchwitz/status/1112727820042727424 https://twitter.com/NicolaiBuchwitz/status/11127278200427274... https://youtu.be/4iaInDiEiQg?t=338 https://youtu.be/4iaInDiEiQg?t=338

cfstras 7y ago
Awesome, thanks for the info! Does the hardware watchdog work when halted because of over-temp?
- l1k 7y ago
  You mean the watchdog integrated into the BCM2835? That's a good question, we haven't tested that yet, but I've added it to the todo list now. One particular product in the Revolution Pi lineup called "Connect" has an additional hardware watchdog which is also capable of resetting attached devices via a relay. That one works even when the BCM2835 has locked up completely. However, the CPU needs to have cooled down a bit to reboot successfully.