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VNC1L Programming Over USB
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The VNC1L device can be programmed from a PC USB port using an FTDI USB-serial converter device such as the FT232R, FT232BM or FT8U232AM. This is the fastest way to reprogram the VNC1L Flash memory as data can be transferred to the Vinculum device at up to 1MBaud.

The MM232R
and UM232R provide a convenient way of interfacing the FT232R to a Vinculum VNC1L design or the VDIP1 evaluation module and will allow for programmatically controlling the state of the PROG# and RESET# pins.

FTDI's standard Vinculum evaluation kits (VDRIVE1
, VMUSIC1, VF2F) all have a 6-pin header which can be interfaced to the FT232R-based TTL-232R-3V3 cable to allow firmware reflashing and require a jumper to be set to enable the bootloader at power up.

The required connections between the VNC1L and an FT232R device for programmatically controlling the PROG# and RESET# pins is shown below:


Note that CBUS Bit Bang mode must be enabled in the FT232R EEPROM for CBUS2 and CBUS3 for this to function (see AN232R-01 Bit Bang Modes for the FT232R and FT245R
for details of CBUS Bit Bang mode). To enable the bootloader, the PROG# pin must be driven low and the VNC1L must then be reset by driving the RESET# pin low then high. Run mode can be enabled by driving the PROG# pin high and then resetting the VNC1L by driving the RESET# pin low then high.

If using an FT232BM, FT8U232AM or an FT232R without using CBUS bit bang on CBUS2 and CBUS3 to programmatically control the PROG# and RESET# pins, a jumpered configuration is required as follows:


Note that for the bootloader to be active the jumper must be fitted before powering the VNC1L. If the jumper is not fitted, the VNC1L will power up in run mode with the bootloader inactive.

Both of the configurations above are supported by the VPROG application
which can be downloaded from the Vinculum web site.