Microsd Slot - Digilent ZYBO Reference Manual

ZYBO™ FPGA Board Reference Manual
Two on-board status LEDs provide visual feedback on traffic flowing through the port: the transmit LED (LD9) and
the receive LED (LD8). Signal names that imply direction are from the point-of-view of the DTE (Data Terminal
Equipment), in this case the PC.
The FT2232HQ is also used as the controller for the Digilent USB-JTAG circuitry, but the USB-UART and USB-JTAG
functions behave entirely independent of one another. Programmers interested in using the UART functionality of
the FT2232 within their design do not need to worry about the JTAG circuitry interfering with the UART data
transfers, and vice-versa. The combination of these two features into a single device allows the ZYBO to be
programmed, communicated with via UART, and powered from a computer attached with a single Micro USB
cable.
7

MicroSD Slot

The ZYBO provides a microSD slot (J4) for non-volatile external memory storage as well as booting the Zynq. The
slot is wired to Bank 1/501 MIO[40-47], including Card Detect. On the PS side peripheral SDIO 0 is mapped out to
these pins and controls communication with the SD card. The pinout can be seen in Table 4Error! Reference
ource not found.. The peripheral controller supports 1-bit and 4-bit SD transfer modes, but does not support SPI
mode. Based on the Zynq TRM, SDIO host mode is the only mode supported.
The SD slot is a powered from 3.3V, but is connected through MIO Bank 1/501 (1.8V). Therefore, a TI TXS02612
level shifter performs this translation. The TXS02612 is actually 2-port SDIO port expander, but only its level shifter
function is used. The connection diagram can be seen on Figure 6. Mapping out the correct pins and configuring
the interface is handled by the ZYBO board definition file.
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Figure 5. USB-UART bridge.
Signal Name Description
SD_D0 Data[0]
SD_D1 Data[1]
SD_D2 Data[2]
SD_D3 Data[3]
SD_CCLK Clock
SD_CMD Command
SD_CD Card Detect
Table 4. MicroSD pinout.
Zynq Pin SD Slot Pin
MIO42 7
MIO43 8
MIO44 1
MIO45 2
MIO40 5
MIO41 3
MIO47 9
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