An external pulldown reset switch, connected to the RST solderpad, will reset the board, just like pressing the RST button. But an external pulldown bootselect switch, connected to the BOOT solderpad, has no function ? What do I miss ?
The schematic is here if that helps?
So, the onboard Boot button works?
But your added Boot button doesn’t?
Is your switch a momentary switch?
Thanks.
Onboard BOOT button works, added does not. Momentary, but held down during reset.
The schematics show 2* 4k7 resistors in the USER_SW circuit. Pulling down external will result in 1.65V at R4 instead of 0V with the SW_BOOT switch. Which seems insufficient to be detected as low.
Perhaps the solderpad should have been labeled as SW_C, ie. the third user switch.
A workaround for me is to set GPIO 22 as FUNC_SIO, input and pulled up. Then, when the switch is detected, call reset_usb_boot(0,0) from pico/bootrom.h. The board then resets and enters the USB programming mode.