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VPROG VNC1L Reflasher Hardware Considerations
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In order for the VNC1L to be reprogrammed, the device must be powered up with its bootloader active. This is done by powering the chip up with the PROG# pin tied low. The PROG# pin may be controlled in two ways:

·Manually by a jumper  
·FT232R CBUS pins can be used to programatically set the VNC1L chip into program mode  

NOTE: If the firmware in the VNC1L should become corrupted, the device is only recoverable via the UART and bootloader. All VNC1L designs should provide access to the UART, PROG# and RESET# pins to allow for device recovery.

The VPROG application attempts to set program mode using CBUS2 of an FT232R device (connected to PROG# on the VNC1L) and then reset the VNC1L to run mode using CBUS3 (connected to RESET# on the VNC1L). For the PROG# pin to be controlled programatically, the FT232R device is required because it uses the CBUS bit bang mode which is only available on the FT232R. Other FTDI USB-serial devices may be used to reprogram the VNC1L using the VNC1L Reflasher application, but program mode must be set using a jumper.

To use CBUS bit bang mode on the FT232R it must be enabled in the EEPROM (see AN232R-01 Bit Bang Modes for the FT232R and FT245R
). An example suitable MProg configuration for an FT232R device to be used in this way is shown below. MProg is available as a free download from the FTDI web site.


An example block diagram of how to connect an FT232R device to the VNC1L is shown below.