This happened a lot sooner than I would have guessed! I thought the 4 was gonna get milked for many more years. It'll still be around no doubt but the speed bump is appreciated.
Interesting to see the emergence of a southbridge chip in SBC land. RPI4 using a Via USB3 controller and a dedicated Broadcom ethernet chip is somewhat against the grain of most embedded chips, which tend to have all this io on package. Here Broadcom now has a single chip that bundles a bunch of the io needs together, and takes back the business from Via, which is a tailored step forward to combine functions. But it's still a secondary chip, which is fairly unusual.
On the upside, it means less pins on the main core. And it physically helps fan out the io, can be placed closer to io connectors. I went looking for a chip identification for RPI4, but didn't find it; I'm curious whether old chips had discrete PHY or whether they were builtin, and what the situation is with the new southbridge.
Around the start of this year they were saying the Raspberry Pi 5 would be released next year, so it’s about a quarter or two earlier than previously expected.
Part of the reason for the separate IO chip is that it can use an older silicon process (40nm) than the main chip (16nm) which makes it easier to have robust GPIO pins.
Interesting to see the emergence of a southbridge chip in SBC land. RPI4 using a Via USB3 controller and a dedicated Broadcom ethernet chip is somewhat against the grain of most embedded chips, which tend to have all this io on package. Here Broadcom now has a single chip that bundles a bunch of the io needs together, and takes back the business from Via, which is a tailored step forward to combine functions. But it's still a secondary chip, which is fairly unusual.
On the upside, it means less pins on the main core. And it physically helps fan out the io, can be placed closer to io connectors. I went looking for a chip identification for RPI4, but didn't find it; I'm curious whether old chips had discrete PHY or whether they were builtin, and what the situation is with the new southbridge.