drgeoff wrote: ↑
Mon Mar 19, 2018 7:32 pm
fruitoftheloom wrote: ↑
Mon Mar 19, 2018 4:16 pm
Actually I should of said "flipped" which was mentioned somewhere......my bad!
The relevance was comparing making a 2B out of a 3B to feasibly making a 2B+ out of a 3B+........
I see no relevance. Can you convince me otherwise?
Okay... The change from '2837A0 to '2837B0 is a "step change". It's a "minor" upgrade to the chip. so if the B0 stepping were to put into the old package, nobody would have noticed, absent an announcement, even though the changes to the boot ROM may have some fairly profound effects. The bigger issue here is that the actual Silicon chip has been "flipped". That is, it is in the package upside down compared to the old package. The chip has a lot of connections to the package--that ball grid array that is used to solder it to the PCB. By flipping the Silicon, the chip connections are no longer in the same places they were...at least, they aren't unless a mirror image operation was also carried out, and we have heard nothing about *that* being done.
Therefore, the assumption pretty much has to be made that the package to PCB connections are reversed in some way between the the two *package* versions (otherwise, the internal package wiring would get really, really...ugly). And that means that stuffing a '2837B0 onto a Pi2Bv1.2 PCB will not work. The connections are in the wrong places. That leads to two possible solutions, both of which are *probably* viable if the RPT wants to use them. The first is either a modified Pi3B+ PCB that doesn't connect or terminates the WiFi/BT connections or just uses a Pi3B+ PCB and doesn't even populate the WiFi/BT circuit area. The second is to have '2837B0 Silicon packed in the "old style" (that is, the one being used for the '2837A0 chip) and use that on the current Pi2Bv1.2 PCB.
The former approach would gain all the benefits of the Pi3B+ that pertain to the Pi2B (faster wired Ethernet, improved boot ROM, improved thermal management, PoE capability). The later approach would gain the improved boot ROM and perhaps a bit of a speed boost, but not much..
As I see it...is the improved boot ROM alone worth the change? I would argue that it is. Others will--obviously--differ.