One card, no compatibility lottery. The SAPSAN 32 GB U3 microSD card was selected for Flipper Zero, uConsole, and Raspberry Pi users. Instead of trusting the symbols printed on the card, we verified its full capacity, data integrity, and real operation with Flipper Zero and uConsole.
U3 instead of the typical U1
Many basic 32 GB cards are still rated U1. SAPSAN is U3, which means a minimum sequential write speed of 30 MB/s in a compatible UHS mode - three times the minimum performance class of U1 at 10 MB/s. This provides more headroom when flashing an operating system and transferring data. Flipper Zero uses an SPI interface, so we confirmed its compatibility in a separate test.
Tested by SAPSAN, not merely described
As part of our internal testing, we installed the stable Momentum mntm-012 firmware on the card. Flipper Zero booted correctly and recognized FAT32 and 29.10 GiB of capacity. The card is sold without Momentum preinstalled - the installation was used solely to test compatibility.
Flipper Zero: positive result
- SPI write for 256-1024 B blocks: 262-307 KiB/s,
- SPI read for 256-1024 B blocks: 410-551 KiB/s,
- official minimum write speed required by Flipper Zero: 260 KiB/s.
Full capacity: zero errors
F3 wrote and read back 29.03 GB of data, or 60,873,440 sectors. Result: 0 lost, 0 corrupted, 0 changed, and 0 overwritten sectors. Average throughput during this full test through a USB 2.0 reader was 20.76 MB/s when writing and 29.68 MB/s when reading. This confirms the actual capacity of the storage medium, not merely the controller declaration.
uConsole: system test
We booted ClockworkPi Bookworm from the card directly in uConsole. The device negotiated UHS-I SDR104 mode at 200 MHz, while a fio 3.33 direct I/O test on a 1 GiB file achieved 36.93 MiB/s write and 89.19 MiB/s read.
- 4K random read: 2,400 IOPS,
- 4K random write: 523 IOPS,
- after the workload: 0 MMC, CRC, I/O, and ext4 errors.
The test confirmed not only successful system boot, but also stable card operation under sustained and random workloads.
Applications
- Flipper Zero - firmware, applications, files, and databases,
- uConsole - operating system storage; compatibility confirmed with ClockworkPi Bookworm,
- Raspberry Pi and other devices supporting microSDHC.
Specifications
| Capacity | 32 GB, 29.10 GiB visible in testing |
| Format | microSDHC |
| Interface | UHS-I |
| Speed class | Class 10, U3 |
| Model | MMSZ32GU3FXE4-T0 |
| Country of manufacture | Taiwan |
Package contents: 1 × SAPSAN 32 GB U3 microSD card, without preinstalled firmware.
