GMS30C7201 Datasheet, PDF (274/352 Pages) Hynix Semiconductor – 60MHz operation frequency Low power consumption

Slow AMBA Peripherals
13.8 Synchronous Serial Interface
The SPI is a high-speed synchronous serial port for communicating to external devices. The SPI
in this document is for MMC.
As with any other SPI device, the SPI-MMC circuit consists of the following four signals:
• CS
Host to card chip select signal
• SPICLK
Host to card clock signal
• MOSI
Host to card data signal
• MISO
MMC to host data signal
SPI-MMC is byte-orientated and every command, response and data block is built with a byte
(8-bit). SPI-MMC messages are built from command, response and data-block tokens. All
communication between CP and MMC is controlled by the CP (master).
Serial data transmission through SPI starts when the chip-select (CS) is asserted (ie. when the
CS goes to LOW) and ends when the chip-select is released (ie. when the CS goes to HIGH).
Every MMC token transferred on the data signal is protected by CRC bits. But MMC offers a
non-protected mode that enables a system built with reliable data links to exclude the hardware
or firmware required for implementing the CRC generation and verification functions.
In the non-protected mode, the CRC bits of the command, response and data tokens are still
required in the tokens; they are, however, defined as “don’t care” for the transmitters and are
ignored by the receivers.
MMC is initialized in the non-protected mode. The CP can turn this option on and off using the
CRCONOFF command (CMD39). We assume that CRC is processed by software.
13.8.1 Input and output signals
Figure 13-4: Block diagram of the SPI-MMC on page 13-47 shows the input and output
signals of the SPI-MMC circuit. Remember that the APB is an internal peripheral bus.
13-46
GMS30C7201 Data Sheet