2 months agoPosted by nsanfa 35 points 4 replies
Currently I am working on a project that uses the memory AT25SF321. In some devices the flash operates at 40MHz perfectly and in other devices the flash does not work properly at clock frequencies higher than 33MHz (same hardware and firmware).
For instance, when I read the manufacturer and device ID at 40MHz I get the correct response (0x1F, 0x87, 0x01) from some devices and from others I get 0x0F, 0xC3, 0x81. Bit wise it seems to be a shift, like the flash is not handling correctly the timing at the start of the response. If I reduce the clock frequency to 30MHz the flash works perfectly.
The ID (on the chip) of a "faulty" flash and of one that works properly are the same: "adesto1949 25SF321 SSHD".