EVB-USB5734 Datasheet, PDF (15/37 Pages) Microchip Technology – EVB-USB5734 Evaluation Board User’s Guide

To select the SPI device, set the Config. Select switch (SW7) to the SPI position. The
blue “SPI” LED will light. Note that the CFG_BC (Configuration Battery Charge) and
CFG_Non-Rem (Configuration Non Removable) options are now de-selected. All con-
figuration in SPI mode is done by the SPI.
Note: If the SPI Flash is not properly programmed or has an invalid signature, the
USB5734 will default to internal defaults even if the SPI Flash is selected.
FIGURE 2-4:
SPI SELECT
The pull-up resistors (R42 and R58) on the SPI device’s Write Protect (WPn) and Hold
(HOLDn) pins must be populated in order to use external flash. The pull-up resistor
(R61) on the SPI_CE_N pin of the USB5734 must also be populated in order to select
60MHz SPI operation, as opposed to 30MHz operation. Additionally there must be a
jumper placed across the J10 SPI CE# EN header in order to enable the SPI
device.The external flash can be programmed using the Microchip ProTouch2 MPT
software tool which can be downloaded from the Microchip website at
http://www.microchip.com/ProTouch.
Note: Refer to the Protouch MPT User Manual on using this software to program
the configuration.
2.4.2 SMBus
If a SPI Flash device is not found, the firmware checks if the SMBus is enabled. To
select SMBus configuration, set the Config. Select switch to the Strap position. The
green “Strap” LED will light.
The SMBus interface must have correct pull-up resistors applied by external circuitry
to function properly. The USB5734 can operate in SMBus Slave or I2C Bridging mode.
To operate in SMBus Slave mode, install a jumper across pins 1 and 2 of the J5 and
J27 SMBus headers. These jumpers are required in order to enable SMBus communi-
cation. To operate in I2C Bridging mode instead, the J5 and J27 SMBus headers must
be left open.
Note: If the USB5734 is configured for SMBus Slave operation, the DUT will wait
indefinitely for data from the SMBus interface and will not enumerate until
instructed by the SMBus interface.
 2015 Microchip Technology Inc.
DS50002350B-page 15