Other projects • Re: Pi 5 16GB SDRAM test

I have the datasheet but can't post it here due confidentially clauses, but this family of Micron ram chips are LPDDR4x with a backward compatibility setting to operate in LPDDR4 specifications.

I hadn't gone looking for the datasheet. I was just going by what Mouser et al are advertising it as on their product pages. No secret sauce for MT53E family parts anyway as the datasheets are widespread.

You need to connect to the debug UART connector on the Pi 5 that is between the HDMI sockets. https://datasheets.raspberrypi.com/debu ... cation.pdf has the pinout. Settings are 115200 8N1 3.3V. It will display the results of the RAM probing. The debug output is always enabled for Pi 5 due to the dedicated UART and doesn't require any special configuration unlike older Pi models.

Code:

RPi: BOOTSYS release VERSION:e02d33b3 DATE: 2023/12/06 TIME: 18:29:25BOOTMODE: 0x06 partition 0 build-ts BUILD_TIMESTAMP=1701887365 serial 00000000 boardrev d04170 stc 918175AON_RESET: 00000003 PM_RSTS 00001000RP1_BOOT chip ID: 0x20001927PM_RSTS: 0x00001000part 00000000 reset_info 00000000PMIC reset-event 00000000 rtc 00000000 alarm 00000000 enabled 0uSD voltage 3.3VInitialising SDRAM 'Micron' 32Gb x2 total-size: 64 Gbit 4267DDR 4267 1 0 64 152

Awesome thanks so much I'll try get this to work

I hope you get 16GB RAM to work. The previous thread

https://forums.raspberrypi.com/viewtopi ... 6#p2100966

indicated that as of Apr 2023 there were no known 16GB parts suitable for the Pi 5. Over time available RAM chips have changed as have revisions of the Pi 5.

In the thread

https://forums.raspberrypi.com/viewtopic.php?t=369585

It was observed the memory bandwidth of the 8GB Pi 5 was significantly lower than the 4GB model. The way I understood it was that 8GB simply takes longer to refresh. If so, then one might expect a 16GB model to be even slower. It would be interesting to know.

Statistics: Posted by ejolson — Tue Jun 11, 2024 4:32 am

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