spaceman5
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Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Sun Aug 25, 2019 5:36 am

Hi


I have a question about RPi's hardware.

Is the Micro-SD Card slot connected to the SoC directly, or via some Controller Chip?

If it's with a Controller chip, what is the chip?


Thank you

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rpdom
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Sun Aug 25, 2019 11:43 am

Directly.

spaceman5
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Sun Aug 25, 2019 12:07 pm

Interesting.
Thank you for the answer.

BTW, what is the fastest micro-SD card that it supports?

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rpdom
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Sun Aug 25, 2019 12:23 pm

All micro SD cards are supported. Some may be faster than others. The Pi 4 has a much faster SD interface than previous models.

spaceman5
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Mon Aug 26, 2019 4:29 pm

rpdom wrote:
Sun Aug 25, 2019 12:23 pm
All micro SD cards are supported. Some may be faster than others.
I understand.

The purpose of my question, is to buy the fastest microSD card that RPi 4B supports,
but not faster than that.

A faster card than RPi's max speed will work, as you say,
but will cost much more, yet this extra speed will not be utilized..

So for this reason, it will help to know what the SoC can get to..


If anyone knows this information, or did an experiment to test it,
please write, it will be useful information for many people.

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FTrevorGowen
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Mon Aug 26, 2019 8:01 pm

spaceman5 wrote:
Mon Aug 26, 2019 4:29 pm
rpdom wrote:
Sun Aug 25, 2019 12:23 pm
All micro SD cards are supported. Some may be faster than others.
I understand.

The purpose of my question, is to buy the fastest microSD card that RPi 4B supports,
but not faster than that.

A faster card than RPi's max speed will work, as you say,
but will cost much more, yet this extra speed will not be utilized..

So for this reason, it will help to know what the SoC can get to..
...
It will also depend what you mean by "fastest" eg. fastest control/data transfer rate (communication interface mode), fastest read, fastest write (will also depend on the type of read/write AIUI). For example it's been discovered that the "overall performance" of (some) "faster" A2 cards can be worse than "slower" A1's. Why do you wish to "buy the fastest" (or what do you think you'd gain by doing so)? For most folks "best value" Gb/buck" is likely to be more important (or, to put it another way, there are other potential "bottlenecks" in overall performance of a Pi ...) And remember, the uSDHC card is not the only storage device and for quite a lot of the time a Pi will not be reading or writing to/from it ie. processing will be RAM-based (much faster).
Trev.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, A+ and a B2) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

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Imperf3kt
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Mon Aug 26, 2019 11:30 pm

spaceman5 wrote:
Mon Aug 26, 2019 4:29 pm

The purpose of my question, is to buy the fastest microSD card that RPi 4B supports,
but not faster than that.

A faster card than RPi's max speed will work, as you say,
but will cost much more, yet this extra speed will not be utilized..
In my experience, the difference in price is almost quite literally, pennies.
Get the best card you can, you might decide to reuse it later on a device that does make use of the extra speed.
There are other benefits too such as increased life - would you rather buy two 16GB cards that last 10,000 write cycles each for $10 or one 16GB card that lasts 100,000 write cycles for $15?

*Numbers not based on any data.*
Currently A1 cards from SanDisk are the recommended choice.
55:55:44:44:4C
52:4C:52:42:41

spaceman5
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Tue Aug 27, 2019 4:42 am

Imperf3kt wrote:
Mon Aug 26, 2019 11:30 pm
In my experience, the difference in price is almost quite literally, pennies.
Between the Sandisk Ultra (White) and Sandisk Ultra (Red) - A1, you are right, the difference is negligible.
But between the Sandisk Ultra (Red) - A1 and the Sandisk Extreme (Red+Gold) A2, the price doubles.

Imperf3kt wrote:
Mon Aug 26, 2019 11:30 pm
Currently A1 cards from SanDisk are the recommended choice.
A nice table that summarizes A1 and A2 specification:
https://havecamerawilltravel.com/photog ... eed-class/

fruitoftheloom
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Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Tue Aug 27, 2019 4:47 am

spaceman5 wrote:
Sun Aug 25, 2019 12:07 pm
Interesting.
Thank you for the answer.

BTW, what is the fastest micro-SD card that it supports?


http://www.pidramble.com/wiki/benchmarks/microsd-cards
Retired disgracefully.....
This at present is my daily "computer" https://www.asus.com/us/Chrome-Devices/Chromebit-CS10/


spaceman5
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Joined: Sun Aug 25, 2019 5:26 am

Re: Is the Micro-SD Card Slot Connected to the SoC Directly, or via a Controller Chip?

Tue Aug 27, 2019 8:15 am

BTW fruitoftheloom,
do you maybe know some webpage that shows Temperature measurements of the RPi 4B,
while doing various operations/states?


I created a thread asking about it, but haven't got a reply with an answer for that yet..

It's here, If you have any info to give:
https://www.raspberrypi.org/forums/view ... ?p=1526359


Thank you

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