RiccardoMoretti wrote: ↑
Tue Jun 25, 2019 11:38 am
All good many thanks, I just wasn't sure of the power management chip (MxL7704) but I did find a picture of the Pi and I saw the part number from there, just would have been nice to see that on the schematic
I agree. It may not be that useful for most people but is useful for some, but not that useful when the parts are proprietary and datasheets are not available.
Knowing what parts were originally used and what is actually fitted has been useful in identifying some issues which have arisen when parts have changed. This was the case when a replacement regulator made a Pi much more sensitive to small 5V drops than it previously was.
It also allows people to double-check that everything is how it should be, identify issues there may be, as might have been the case with the PoE HAT issue.
Knowing the part numbers is also useful for figuring out what the lowest voltage a Pi can run at is, though that's complicated by not having full circuit diagrams as well as not having datasheets.
Talking of 'wanting to know': Can anyone read the part number of the Boot Eeprom on a Pi 4 ?
I'm guessing it's the chip near the GPIO on the rear of the board given the solder pad jumpers -
https://raspi.tv/wp-content/uploads/201 ... _700-1.jpg
Thoygh it might be one of the two 8-legged chips to the lower left of the VIA USB chip -
https://raspi.tv/wp-content/uploads/201 ... 4B_700.jpg
I was thinking the Boot Eeprom could be used to hold Videocore bare metal code, so one can have an entirely embedded Pi system bootable without any SD Card or anything else connected. But to pursue that it would be useful to know its write-erase lifetime and for that one needs to know the part number. I haven't so far found a photo which I can read that on, and that's not even included on the schematics.
One thing which does intrigue me on the Pi 4B schematic is what "WB_VBAT" is used for ?
Could "WB" be Watch Battery ? Or Something