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Forum Index : Microcontroller and PC projects : CMM2 SD speeds.
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KeepIS Guru  Joined: 13/10/2014 Location: AustraliaPosts: 1351 |
I thought I'd post the results between two of my SD cards. A week ago I threw together a quick test program to test SD speeds. The idea was to test the difference between Normal and Fast modes with a few of my SD cards, and I posted that in another thread where they really don't belong. Basically I wanted to compare a lot of small file size SD write/read/del cycles, and to quickly change the sizes and number of files, along with a quick switch between Normal and Fast modes. I can select between 1 and 150 files to create/ save/ read and delete and time the result. File sizes range from 80x60 to 800x600 in 9 steps (0 to 9). I had forgotten that my Tiny NUC PC had a 64GB SanDisk in it, formatted to exFAT. So a quick comparison followed, results are interesting, either the exFAT files system is slightly slower that FAT32 or I'm seeing differences in SD card speeds, which implies that SD read write functions in CMM2 are running quite fast. FYI the code I'm using: SpdTestbasZip SD 32GB SanDisk Extreme PRO. FAT32 Normal V Fast For 1 * 800x600 image: Normal Fast Write 2.289 sec 1.921 sec Read 1.28 sec 855ms Delete 5.6ms 5.5ms For 150 * 87x67 images: Normal Fast Write 9.786 sec 8.139 sec Read 3.919 sec 2.822 sec Delete 1.567 sec 1.199 sec And the difference in fast mode between the two. SD 64GB SanDisk Extreme. exFAT SD 32GB SanDisk Extreme PRO. FAT32 For 1 * 800x600 image: Fast 64GB Fast 32GB Write 2.536 sec 1.921 Read 1.224 sec 855ms Delete 3.673ms 5.5ms For 150 * 87x67 images: Fast 64GB Fast 32GB Write 14.279 sec 8.139 Read 4.374 sec 2.882 Delete 1.671 sec 1.199 Mike. It's all too hard. Mike. |
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SimpleSafeName Senior Member  Joined: 28/07/2019 Location: United StatesPosts: 286 |
Interesting, that's good information to know. Thanks! |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1351 |
Partitions and Formatted the 64GB Extreme SD as FAT32 and rerun the tests. COL1: SD 64GB SanDisk Extreme - exFAT. COL2: SD 64GB SanDisk Extreme - Formatted FAT32 as a 32GB drive. COL3: SD 32GB SanDisk Extreme PRO. The 32GB and 64GB are both rated as V30. For 1 * 800x600 image: exFAT FAT32 32GB SD Extreme PRO FAT32 Write 2.536 sec 2.587 sec 1.921 sec Read 1.224 sec 1.243ms 855ms Delete 3.673ms 8.269ms 5.5ms For 150 * 87x67 images: exFAT FAT32 32GB SD Extreme PRO FAT32 Write 14.279 sec 10.722 sec 8.139 sec Read 4.374 sec 3.510 sec 2.882 sec Delete 1.671 sec 1.469 sec 1.199 sec Testing with 1 larger file FAT32: Delete changes from test to test and is much higher R/W times are similar. Testing with 150 small files FAT32: Times are consistent and less than exFAT format. This SD is slower than the Extreme PRO 32GB. From this small test, it appears that the speed rating of the SD is important on the CMM2. Mike. . . Edited 2020-07-05 18:36 by KeepIS It's all too hard. Mike. |
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| RC_tech Newbie  Joined: 05/07/2020 Location: GermanyPosts: 14 |
What picture format were you using? an 800x600 image has in BMP, GIF, PNG and JPG vastly different sizes. A better test would be to create simple sequential text files, write different lengths and read them back. But anyway, I don't think that storage speed is very important on the CMM2. Amiga, C64 and so on used disk drives which were much slower, and everything worked. But there's one thing: The C64 demoscene has the NUVIE video format, which are essentially lots of NUFLI images, loaded from SD card and stored in the REU. The REU (RAM Expansion Unit) is no main meory, it is organized in up to 256 blocks of 64K. But it contains a controller chip which allows to read, write or exchange RAM contents between main memory and REU memory very quickly. This way it's possible to play full motion video on the C64, with 0.985 MHz. Has somebody tried this on the CMM2? Storing lots of still images in the memory and playing them as video? Greets, RC. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1351 |
I didn't set out to test the CMM2 for typical PC usage of moving large numbers of small files, and you obviously know why that's important in HDD/SDD testing. It's just a quick way to get a relative difference in time taken for up to 150 BMP image files to be written and read back. There are other speed test programs on here for more extensive file and CPU testing. The CMM2 saves files as a BMP image, this is what was tested. Obviously the CMM2 can display other graphic file formats and these can be faster such as jpeg (smaller size and onboard HW decoder), or slower to load such as gif. Mike. It's all too hard. Mike. |
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