User guide
20 CY3687 MoBL-USB FX2LP18 Development Kit User Guide, Doc. # 001-68582 Rev. *B
Development Board
The MoBL-USB loader determines the EEPROM size by first initiating an I
2
C transfer to address
Alignment not proper between these 2 lines.
If the above transfer does not return an ACK pulse, the MoBL-USB loader initiates a second I
2
C
transfer, this time to address 10100001 (1010=EEPROM, sub-address 001). If an ACK is returned
by the I
2
C device, the MoBL-USB loader writes two EEPROM address bytes to initialize the internal
EEPROM address pointer to ‘0’.
If neither transfer returns an ACK pulse, the MoBL-USB Development Board does not connect to
USB. MoBL-USB requires a 0xC2 format EEPROM to connect. Three MoBL-USB startup
sequences, and the associated settings for SW1 and SW2, are as follows:
1. Safe Mode:SW2 = SAFE, SW1 = either position
This setting selects the EEPROM located in socket U5. Since the MoBL-USB chip comes out of
reset disconnected from USB, an EEPROM is required to connect to the USB. The ‘Safe’
EEPROM is used for this purpose. The ‘Safe’ EEPROM contains simple firmware that connects
to the USB and responds to descriptor requests with the Cypress VID and the MoBL-USB PID.
‘Safe’ mode is used to allow the development board to enumerate when no action other than a
USB connect is required. For example, the ‘safe’ setting could be used if one of the other
EEPROMs on the board is accidentally programmed with malfunctioning firmware. Once it is run-
ning, SW2 can be switched to the LG-SM position to allow 8051 programming or other access to
the other EEPROMs. The source firmware for this EEPROM is located in the
<Installed_directory>\<Version>\Firmware\Connect directory. The actual EEPROM
image is stored in the LP18_safe.iic file.
2. C2 Load Small EEPROM:SW2 = LG-SM, SW1 = SMALL
This setting selects the EEPROM located in socket U8. The I
2
C EEPROM address pins for this
socket are strapped to ‘000’. This socket only supports single-byte address EEPROMs. This
EEPROM is pre-programmed at manufacturing with simple firmware which connects to USB and
responds to descriptor requests with the Cypress VID (0x04B4) and the MoBL-USB Development
Kit PID (0x0086). This VID/PID is associated with a driver which automatically downloads the Keil
debug monitor to the development board. The source firmware for this EEPROM is located in the
<Installed_directory>\<Version>\Firmware\Connect directory. The actual EEPROM
image is stored in the LP18_dvk.iic file.
3. C2 Load Large EEPROM:SW2 = LG-SM, SW1 = LARGE
This setting selects the EEPROM located in socket U8. The I
2
C EEPROM address pins for this
socket are strapped to ‘001’. This socket only supports double-byte address EEPROMs. This
EEPROM is pre-programmed at manufacturing with the bulkloop example firmware
(VID=0x04B4, PID=0x1004). The source firmware for this EEPROM is located in the following
directory:
<Installed_directory>\<Version>\Firmware\bulkloop.
The actual EEPROM image is stored in the bulkloop.iic file. Note that if an EEPROM is con-
nected to the SCL and SDA lines, but does not contain an 0xC2 formatted EEPROM, the device
does not connect to USB. Therefore, it cannot be programmed. Always connect to the SAFE
EEPROM if you are not using one of the programmed EEPROMs. See the MoBL-USB datasheet
or MoBL-USB Technical Reference Manual for additional information on supported EEPROM for-
mats.