What are the options for loading program code into the STM32L072RB?

[JCoti]

I planned to use the ST-LINK V3SET interface, with the 14 pin target JTAG interface (Table 6 in UM2448 Rev 1), but the JTAG signals/pins/functions are not listed in the datasheets or CubeMX pin configurator. 

Does this part not have the JTAG interface? Are the only options for loading code through serial peripherals, for example USB in DFU mode?

[waclawek.jan]

The default interface to program (and debug) the STM32 is SWD (a 2-signal interface). JTAG (4-signal) is not supported on the Cortex-M0/M0+-based mcus ('F0, 'L0), but that's no drawback, JTAG is rarely used with these chips as it provides no benefit as far as debugging/programming goes, and costs 2 pins more.

The built-in bootloader allows to use the "serial peripherals", as you've said; this varies from chip to chip, for the painful details refer to AN2606.

JW

[JCoti]

Thank you! I presume the ST-LINK interface is an appropriate means of connecting a PC to the target SWD pins?

[Tesla DeLorean]

Yes, the ST-LINK predominantly uses SWD connectivity in the NUCLEO and DISCO boards.