5 ms·

It's a neat way to teach people how to program distributed systems at this scale but I don't understand why they wouldn't use the Raspberry Pi Compute Moudle in

by bradfa 9y ago

It's a neat way to teach people how to program distributed systems at this scale but I don't understand why they wouldn't use the Raspberry Pi Compute Moudle instead of normal Raspberry Pis. Using the Compute Modules would, I'd think, make for a much easier to integrate system, even possibly allowing higher density of processors per unit volume.

danielvf 9y ago
Raspberry Pi Compute Modules don't have ethernet built in - that would require quite a non-standard networking system, wouldn't it?
- srcmap 9y ago
  Any comments on using Pi Zero as base line module? Supposedly only $5 per PCB from https://www.adafruit.com/product/2885 Power and network can go thru usb. (usbnet)
  - stan_rogers 9y ago
    You'd need to buy them one at a time.
  - squeaky-clean 9y ago
    Like stan_rogers says, you're limited to buying them one at a time from pretty much any retailer. And it's been this way for years, so it doesn't seem like it will change anytime soon. You can find more on eBay, but then they're usually priced $15-20 each and it would still be difficult to buy them in the hundreds.
- bradfa 9y ago
  The Broadcom SoC doesn't have Ethernet built in, it's a USB connected Ethernet on the normal Pis. The USB bus from the SoC is brought out onto the SODIMM connector on the Compute Module so one could easily add Ethernet on the carrier board if needed. The Ethernet used on the normal Raspberry Pi 3 is a Microchip/SMSC LAN9514 USB hub/Ethernet part: http://www.microchip.com/wwwproducts/en/LAN9514 http://www.microchip.com/wwwproducts/en/LAN9514 There are likely other methods of networking, if one wanted to avoid paying for a USB/Ethernet adapter chip for each Compute Module. Such as running a USB gadget on each Compute Module within Linux and have all the Compute Modules connected as USB devices to a USB SS host. If you used USB SuperSpeed hub chips and did the network switching on a non-Raspi SuperSpeed host within Linux (software defined networking!), this could likely easily get high-ish speed (ie: 100+ Mbps) networking working cost effectively, as the SuperSpeed hubs should allow upstream to run at USB SS rates while downstreams all run at USB HS rates, 7 port USB SS hubs aren't that expensive of chips. Microchip sell the USB5807 7-port USB SS hub chip for about $5, which is only slightly more than the LAN9514, as then you'd only need one hub for every 7 Compute Modules instead of one LAN9514 (or similar) per Compute Module. http://www.microchip.com/wwwproducts/en/USB5807 http://www.microchip.com/wwwproducts/en/USB5807

by bradfa 9y ago

danielvf 9y ago

Raspberry Pi Compute Modules don't have ethernet built in - that would require quite a non-standard networking system, wouldn't it?

srcmap 9y ago
Any comments on using Pi Zero as base line module? Supposedly only $5 per PCB from https://www.adafruit.com/product/2885 Power and network can go thru usb. (usbnet)
- stan_rogers 9y ago
  You'd need to buy them one at a time.
- squeaky-clean 9y ago
  Like stan_rogers says, you're limited to buying them one at a time from pretty much any retailer. And it's been this way for years, so it doesn't seem like it will change anytime soon. You can find more on eBay, but then they're usually priced $15-20 each and it would still be difficult to buy them in the hundreds.
bradfa 9y ago
The Broadcom SoC doesn't have Ethernet built in, it's a USB connected Ethernet on the normal Pis. The USB bus from the SoC is brought out onto the SODIMM connector on the Compute Module so one could easily add Ethernet on the carrier board if needed. The Ethernet used on the normal Raspberry Pi 3 is a Microchip/SMSC LAN9514 USB hub/Ethernet part: http://www.microchip.com/wwwproducts/en/LAN9514 http://www.microchip.com/wwwproducts/en/LAN9514 There are likely other methods of networking, if one wanted to avoid paying for a USB/Ethernet adapter chip for each Compute Module. Such as running a USB gadget on each Compute Module within Linux and have all the Compute Modules connected as USB devices to a USB SS host. If you used USB SuperSpeed hub chips and did the network switching on a non-Raspi SuperSpeed host within Linux (software defined networking!), this could likely easily get high-ish speed (ie: 100+ Mbps) networking working cost effectively, as the SuperSpeed hubs should allow upstream to run at USB SS rates while downstreams all run at USB HS rates, 7 port USB SS hubs aren't that expensive of chips. Microchip sell the USB5807 7-port USB SS hub chip for about $5, which is only slightly more than the LAN9514, as then you'd only need one hub for every 7 Compute Modules instead of one LAN9514 (or similar) per Compute Module. http://www.microchip.com/wwwproducts/en/USB5807 http://www.microchip.com/wwwproducts/en/USB5807