My ESP-01 boots up fine when GPIO0, GPIO1, GPIO2, & GPIO3 are not connected to anything (floating) - they are all pulled up high internally.
However, I wish to control a relay with the ESP-01. The way I have done that is by connecting the GPIO pin to the base (via a 1k resistor) of a BJT NPN transistor, and the transistor drives the negative relay coil to ground.
But I think where the problem is is the fact that I connected the GPIO pin to the base of an NPN resistor, and this base is +0.7V from the collector (GND). Therefore, when booting up, the ESP-01 sees a "low" at the GPIO pin (transistor base) thus goes into one of the other modes instead of the operation mode.
How do other people handle this?