MAX14500 Datasheet, PDF (25/41 Pages) Maxim Integrated Products – Hi-Speed USB-to-SD Card Readers with Bypass

Hi-Speed USB-to-SD Card
Readers with Bypass
SD
SLOT 1
CCRD_PRST
CCLK1
CCMD1
4 CDAT1_[3:0]
SD PORT 1 SWITCHES
HCRD_PRST
HCLK1
HCMD1
HDAT1_[3:0]
SD
PORT1
4
D+
CD+
USB
CONNECTOR _D-
CD-
SD CARD INTERFACE
USB HS
CARD READER
USB
TRANSCEIVER
MAX14500–
MAX14503
USB SWITCHES
HOST PROCESSOR
BUSY
BERR
MODE = HIGH
I2C_SEL = LOW
HOST
I/O
HD+
USB
HD-
Figure 11. I2C_SEL is connected low to enable simple control and MODE = 1 to enable Card Reader mode for SD card 1.
Error Checking
In simple control, the BERR/INT output functions as
BERR and indicates if an error occurs during Card
Reader mode. If BERR asserts low to indicate an error,
the MAX14500–MAX14503 stay in Card Reader mode.
If the error clears, data transfer begins. BERR asserts if
KVBUS, V_TM, or V_SD are not present. It is recommend-
ed that MODE be pulled low when BERR indicates an
error to return the MAX14500–MAX14503 to Pass Thru
mode for the host µP to clear the error.
In I²C control, BERR/INT functions as an interrupt out-
put (INT) and asserts for errors encountered in Card
Reader mode when interrupts are not masked. To find
the source of the interrupt, read the interrupt request
registers and status register.
Busy Indication (BSY)
The BUSY output is used in simple control and I²C con-
trol to indicate when Card Reader mode is active. In
simple control, transitioning MODE high to low requests
the internal microcontroller to enable Pass Thru mode.
BUSY asserts low while in Card Reader mode and
deasserts high in Pass Thru mode.
The BSY bit in STATUS1 (0x12) behaves similarly with
I²C control. The BUSY output is represented by the BSY
bit. Requests to put the device to sleep or bypass
(Pass Thru mode) while in Card Reader mode can be
verified by checking the state of the BUSY signal or
BSY bit. The BUSY output indicates the status of the
BUSY flag in STATUS1. The BSY bit is 1 when the
BUSY output asserts low. When enabled, changes in
the busy flag cause an interrupt. In I²C control, either
the BSY bit or the BUSY output give the status of the
busy state.
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