· | 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.