Blog Post Actions
Group Actions
Engagement
  • Author Author: ralphjy
  • Date Created: Date Created
  • Views 1159 views
  • Likes 7 likes
  • Comments 2 comments
Related
Recommended

RP2040 SD Card SPI Benchmark Revisited

ralphjy

For Pi Day, I tried benchmarking the SD card interface on a new SparkFun RP2040 mikroBUS Development Board that I had just gotten - RP2040 SD Card SPI Benchmark.

I was somewhat disappointed in the results - around 140KB/Sec Write and Read.

 commented that he had been able to achieve around 2MB/Sec using a Pi Pico with a hand wired interface to an SD card socket.  I had used the benchmark example that was included with the SDFat library and he had used a somewhat customized program that tweaked the SPI clock frequency and the processor voltage.  He gave me a copy to try and while my results improved, they were still far short of his.  With this program I got around 250KB/Sec.

Of course there are quite a few variables in play.  I am using a SanDisk Ultra 16GB SD card and he is using a SanDisk Extreme Plus 32GB.  I would not have expected my card to be the limiting factor and he also got over 1.5MB/Sec using a ONN (Walmart brand) 32GB card.

The boards are certainly different - The SparkFun board uses SPI1 for the SD card and Bill used SPI0 in his setup.  Maybe I need some extra configuration?

I realized that I have another SD card setup, a Xiao expansion board, and I also happen to have a Xiao RP2040 that I haven't tried.  I checked the schematic and the expansion board uses SPI0 for the SD card.

So, time for some experiments...

Here's the expansion board setup.

image

And the results.  I included a standard Xiao (SamD21 - M0) on the same expansion board for reference.

Board Processor Bench Test  SPI interface Write KB/s  Read KB/s SD Card
Pi Pico RP2040 Modified 0 2010 2100 Sandisk Extreme Plus 32GB
Sparkfun MikroBus RP2040 Stock 1 143 143 SanDisk Ultra 16GB
Sparkfun MikroBus RP2040 Modified 1 255 255 SanDisk Ultra 16GB
Xiao + Expansion SamD21 Stock 0 369 355 SanDisk Ultra 16GB
Xiao RP2040 + Expansion RP2040 Stock 0 476 479 SanDisk Ultra 16GB
Xiao RP2040 + Expansion RP2040 Modified 0 769 768 SanDisk Ultra 16GB

I guess it just shows me that if it really mattered, I should test the SD card speeds in a specific configuration.  I should probably try some other SD cards in my RP2040 configurations (I don't have an Extreme Plus).  Maybe I should try to wire an SD socket to a Pico and see if I can reproduce Bill's results Relaxed.