ALFAT-OM-337 GHI Electronics, ALFAT-OM-337 Datasheet - Page 13

• Manufacturer Part Number: ALFAT-OM-337
• Description: Memory IC Development Tools ALFAT USB / SD to UART / SPI OEM BOARD
• Manufacturer: GHI Electronics

Specifications of ALFAT-OM-337

• Rohs: yes
• Product: SD OEM Board
• Tool Is For Evaluation Of: SD, SDHC, MMC Cards, USB drives
• Memory Type: Flash
• Operating Supply Voltage: 3.3 V
• Description/function: OEM board offers a seamless way to access files on SD & MMC cards and on USB memory drives
• Interface Type: I2C, SPI, UART, USB
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Part # Aliases: GHI-ALFAT-OM-337

4. ALFAT access interface
ALFAT is controlled through UART, SPI or I2C serial interfaces. 2 pins are sampled on
power up to determine the interface. The pins are SPI_SSEL and SPI_MOSI.
On power up, the system should hold ALFAT in reset state until the power is stable. This is
done by holding reset pin low. Then, pins SPI_SSEL and SPI_MOSI must be set to the
desired serial interface, UART, SPI, I2C or even to force the boot loader. The boot loader is
needed for firmware updates. Those pins have internal pull-down resistor so an
unconnected pin is considered low. After pins are set, the reset pin must be set to high
state to allow ALFAT to boot up. Note that the reset pin is NOT 5V tolerant.
ALFAT needs about 30 milliseconds to sample these pins from the time reset pin goes high
then it needs a bit more to initialize the system. We recommend a 50 milliseconds delay
before sending any commands to ALFAT. If the selected interface is SPI, these pins can
be change to their appropriate SPI functions; otherwise, it is safe to leave the pins in the
same state used on power-up.
UART interface uses three hardware signals:
Note: ALFAT access reference code library, available with ALFAT's downloads, provides an
example how to use UART interface.
4.1. Selecting the access interface
4.2. UART Interface
GHI Electronics
Rev. 1.13
•
•
•
UART_TX signal to send data out from ALFAT.
UART_RX signal to receive data to ALFAT.
UART_BUSY signal. This should be monitored while sending data to ALFAT. When
it is high, no more data should be transmitted to ALFAT till it gets low.
SPI_SSEL SPI_MOSI
high
high
low
low
high
high
low
low
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Boot loader
Interface
UART
I2C
SPI
ALFAT access interface
ALFAT SoC Processor
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