To program ESP-07S/12F
You will need a FT232R USB to serial programmer (3.3V only). Check the back of the board for the programming pins and align them with the FT232R side pins (Tx, DTR, RTS, Vcc, Rx, Gnd). The pins on the back are not labelled, however, the square pin in GND. This is a tricky flashing as you will need to align the pins of FT232R with the pads on the PCB on a 45 degree with steady hands and push down (as shown below). You might need to try this multiple times to get a solid connection. Then you can flash the firmware. No need to put the ESP in programming mode, the FT232R takes care of that.