3.1.16：VREF Config
Interface voltage Setting (VREF) is used to set the output voltage of the programmer and the level size of the programmer signal, which generally defaults to 3.3v on power-up, and can be changed by connecting to the PowerWriter® upstream software, refer to the following:
When an external voltage is selected, the target board should be connected to the programmer's power pins and ground along with the external power supply, as it is necessary to use the external input power to power the programmer interface.
Modify the default output voltage when the programmer is powered on, you need to check Save Global Save Voltage:
- When the default output voltage is to be re-modified, the settings need to be updated again once more.
- If you need to turn off this action for different application scenarios, please change the setting to external power input and do not use the power supply of the device itself to control it, as shown below:
VREF (Reference Voltage), VEXT (Extended Voltage) may jump when the chip is not successfully connected, this action is actually trying to execute POR (Power On Reset), which is used to solve the problem of connecting and unlocking when the target chip is in the following two situations:
- Target chip open protection: After some chips open protection again, the RESET pin may not be able to perform reset and can only be reset by POR, at this time, it is necessary to perform POR to communicate with the target chip.
- Target chip internal firmware disables debug port, or multiplexes RESET pin: Some chips run internal firmware that multiplexes the debug port IO, or multiplexes the RESET pin, which may also result in not being able to reset the target chip, and only attempting a POR reset.
Note: Self-output power supply can do POR, external input voltage can't do POR; however, if self-power supply exists on the board, it also can't do POR, the power supply must be controlled by PWLINK.