Pi start up

On the raspberry pi forum it explains that during the boot process after a ‘shutdown’ or ‘halt’ demand, bootcode.bin will wait for pin 5 (GPIO 3 = IIC SCLK) to go low before enacting the restart. This line has a physical pull up resistor.

Thus a push button between pins 5 and 6 (GND) can act as a ‘restart’ command, the Pi remaining in ‘sleep’ mode until then. Asserting the ‘reset’ line (using the ‘RUN’ pad which is present on all recent models) overrides this behaviour and forces a restart (but not a tidy shutdown).

SYS “TaskManager_Shutdown”,162 performs a shutdown/restart cycle. Is there a parameter for this command that puts the Pi into sleep mode until GPIO3 is taken low?