Many SCM systems need external storage devices to store all kinds of data . At present, there are EEPROM,NOR,SLC NAND,SD card ,TF Card, etc . They each have their own advantages , Comprehensive comparison , There is nothing more cost-effective than SD NAND 了 , It can not only support 128MB~4GB, And support SPI Interface , It can meet different application scenarios . compatible SPI NOR Pad size , Occupy PCB When the area is close, it can provide higher density storage , And the unit storage cost is lower . standard SD The protocol makes it easier for users to apply , It saves users the time and trouble of writing drivers . Tradition SLC NAND Users need to do bad block management and ECC adapter ,SD NAND Built in bad block management and ECC Be able to handle automatically , Users no longer need to do management , This is for those who do not have bad block management and ECC The single chip microcomputer with processing ability is very friendly . And SD,TF Card compared to ,SD NAND Have higher environmental tolerance , It's solved SD,TF The card is easy to loose and the golden finger is easy to oxidize .

   CS Creational SD NAND Support at the same time SPI And SD Interface , Mainstream capacity 128MB,512MB,4GByte,6*8mm Small size of , Transmission bandwidth 4-bit, Compared with reading and writing speed SPI NAND faster , The maximum write speed can reach Class 10 Level , It can meet most application scenarios .

SDIO Deal with the SPI A comparison of agreements

   SDIO Deal with the SPI The agreement is relatively ,SDIO Protocol reading and writing SD NAND Faster , Plus its support 4 Line mode , It is using 4 Two data lines , Send... At the same time 4Bits data , Data transmission efficiency is even higher , Occupied at the same time IO More mouth , about IO Users with insufficient mouth will be limited .SPI Mode only takes two IO mouth ,MISO and MOSI, Used as input and output of data respectively , about IO Less talkative users are more friendly .

SD NAND How to work in SPI In mode

   When SD NAND After power on , Only those sent for the first time CMD0 Command can be selected SD NAND Working in SPI In mode . It means , When SD NAND be in SPI In mode , Only by re energizing , To choose again SD Card communication mode , Namely choice SDIO Mode or SPI Pattern , otherwise SD NAND Will always be in SPI In mode . also ,SPI Mode of SD NAND I won't support it V2.0 New commands after version .

Switching between card identification mode and data transmission mode

   And SDIO agreement ,SPI Mode of SD NAND There are also two working modes — Card identification mode and data transmission mode . The process of state machine is as follows ：

initialization SD NAND

SPI Initialization in mode SD NAND The state machine of is as follows ：

Host reads SDNAND Data in

SPI In mode , It still supports reading single block data or multiple blocks of data , The sequence diagram is as follows .

Read single block data

Read multiple pieces of data

Host to SD NAND Write data

Just like reading data , The host can also choose to SD NAND Write a single block of data or multiple blocks of data , The sequence diagram is as follows .

Write a single block of data

Write multiple pieces of data

matters needing attention

1、 Working in SPI Mode of SD NAND There are no longer speed levels , Will be treated as class 0 The speed level of ;

2、SPI Mode not supported SDIO Some commands in mode ;

3、SPI Patterns and SDIO The same command in mode , May have different functions .

CS The advantages of creation

1. CS Yes Flash The ability of controller software and hardware development , Can quickly respond to market demand ;

2. CS There is a smooth upstream industrial chain support , Ensure stable Wafer supply ;

3. CS There are high-quality packaging and testing supporting , Ensure high-quality output .

4. CS Internal firmware can be customized .

5. CS Provide original technical support ,STM32 Reference routine .

6.  Fast delivery （ For small batches in the early stage , We have enough stock ）. In view of the industry 、 Medical care 、 vehicle 、 Customers in power and other industries , We give priority to supply , Free from your worries .

7. more SD NAND Details can be found at ： Chip mounted T card -SD NAND Flash The two generation - Weldable SD card - Patch able TF card -512MB