The following information was astracted from
UFS_Overview_20150821_r0.pdf
M1CCL02-082_Toshiba_UFS_Memory_Overview_for_LGMC_20151022m(S).pdf
M1PCA00-010_TOSHIBA_UFS_Ver2.0_Application_Note_Rev0.1.pdf
151024_Samsung_Flash_Memory.pdf
UFS (Universal Flash Storage)
UFS = SATA High Speed + SCSI Standardization + eMMC Low Power
JEDEC defines UFS as the next generation mobile storage spec
UFS Serial Interface
- the demand for speed and cost has led to parallel communication links becoming deprecated in favor of serial links.
- Speed:
- Clock skew reduces the speed of every link.
- Crosstalk creates interference between the parallel lines
- Cost: The decreasing cost of integrated circuits
UFS AsyncCommand & Command Queuing
- Set it and forget it
- Optimal for multi processing
- Support multiple CMD queuing Maximize parallel programming
- Better throughput through better NAND utilization
- Re-Ordering.
- Command queue execution sequence can be changed by considering NAND interleaving
- Numberof active NAND chips per time is improved
- Suitable for UFS because UFS protocol is a multi-thread, asynchronous protocol
UFS has better features than eMMC
| Items | eMMC | UFS |
|---|---|---|
| Transfer scheme | Sync | Async |
| Command Queue | No(Yes for eMMC5.1) Packed Commands | Yes 32-Queue Depths |
| State | State Transition | Stateless |
| Interface | Parallel/Half-Duplex | Serial / Full-Duplex |
| Priority | No | SCSI Command Priority Higher-Priority LU |
| Abort Scheme | HPI | Task Management Scheme |
| Features | Legacy eMMCFunctions | Same with eMMC |
| Command Set | Legacy eMMCCommands | SCSI Commands |
| Partitions | Boot/RPMB/User Area | 8-LU(including Boot)/ RPMB |
UFS : Simple PCB routing and cost save
Functional Comparison for HW Perspective
| Item | eMMC5.0 | UFS2.0 |
|---|---|---|
| HostI/F Speed | DDR400Mhz | 3Ghzx2Lane(6Ghz) |
| HostSignal Type | CMOS | LVDS |
| I/Oswing Level | 1.8V | 240mV |
| Comm.Type | HalfDuplex | FullDuplex |
| I/OError Detection | CRC16/512Byte | CRC16/272Byte |
| BufferControl | Busysignal | Uniprosupport, RTT |
| Sector Size | 512 Byte | 4096 Byte (RPMB512Byte) |
| RPMB | O | O |
| #Lun | 4 | 8 |
| Boot Partition | O | O |
| Fast Boot | O | O |
| Command Queue | X | O |
| Concurrent Ops. | X | O |
| Secure Trim/Erase | O | O |
| Other eMMC features | O | O |
| Command Protocol | eMMC | SCSI |
New feature list for each standard ver
Memory I/F Trend on Mobile Application