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Quad SPI (QSPI; different to but has same abbreviation as Queued-SPI described in § Intelligent SPI controllers) goes beyond dual SPI, adding two more I/O lines (SIO2 and SIO3) and sends 4 data bits per clock cycle. Again, it is requested by special commands, which enable quad mode after the command itself is sent in single mode.
Before a register access, PHY devices generally require a preamble of 32 ones to be sent by the MAC on the MDIO line. The access consists of 16 control bits, followed by 16 data bits. The control bits consist of 2 start bits, 2 access type bits (read or write), the PHY address (5 bits), the register address (5 bits), and 2 "turnaround" bits.
DataFlash usually had higher capacities than EEPROM in the early days, [when?] and it still provides faster access times. DataFlash capacities in small packages range from 128 kB to 8 MB, while SPI EEPROM capacities in similar packages range from 1 kB to 8 MB . Flash chips are tuned for page access, rather than the byte access used with EEPROM.
EEPROM or E 2 PROM (electrically erasable programmable read-only memory) is a type of non-volatile memory. It is used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems , or as a separate chip device, to store relatively small amounts of data by allowing individual bytes to be erased and ...
Serial flash is a small, low-power flash memory that provides only serial access to the data - rather than addressing individual bytes, the user reads or writes large contiguous groups of bytes in the address space serially. Serial Peripheral Interface Bus (SPI) is a typical protocol for accessing
An example SPI with a master and three slave select lines. Note that all four chips share the SCLK, MISO, and MOSI lines but each slave has its own slave select. Chip select (CS) or slave select (SS) is the name of a control line in digital electronics used to select one (or a set) of integrated circuits (commonly called "chips") out of several connected to the same computer bus, usually ...
SFI has CPU, APIC, Memory Map, Idle, Frequency, M-Timer, M-RTC, OEMx, Wake Vector, I²C Device, and a SPI Device table. SFI provides access to a standard ACPI XSDT (Extended System Description Table). XSDT is used by SFI to prevent namespace collision between SPI and ACPI. It can access standard ACPI tables such as PCI Memory Configuration ...
V pp - Programming mode voltage. This must be connected to the MCLR pin, or the V pp pin of the optional ICSP port available on some large-pin-count PICs. To put the PIC into programming mode, this line must be in a specified range that varies from PIC to PIC. For 5 V PICs, this is always some amount above V dd, and can be as high as 13.5 V.