In SERIAL mode the VLS signer runs on a
Discovery kit with STM32F413ZH MCU
connected by a serial usb cable to the CLNHOST.
The CLNHOST can be any general purpose unix computer capable of
running a lightning node and some associated services.
The TXOHOST can be any general purpose unix computer capable of
running a bitcoind and a txood oracle.
In development and testing the CLNHOST and TXOHOST may be the same host.
Optional instructions for Intel NUC8 Demo Unit Setup
Steps: