PB2 (pin 28) is actually the BOOT1 pin. The Bootloader Document (AN2606) says that the STM32F105xx/107xx bootloader is activated by applying pattern1, which is Boot0(pin) = 1 and Boot1(pin) = 0.
The original Gotek leaves it floating, which might explain why some Goteks seem hard to program.
Probably the best thing would be to use a pull-down resistor and bring the pin to a header (or at least a test point), just in case.
PB2 (pin 28) is actually the BOOT1 pin. The Bootloader Document (AN2606) says that the STM32F105xx/107xx bootloader is activated by applying pattern1, which is Boot0(pin) = 1 and Boot1(pin) = 0.
The original Gotek leaves it floating, which might explain why some Goteks seem hard to program.
Probably the best thing would be to use a pull-down resistor and bring the pin to a header (or at least a test point), just in case.