implement PWT buzzer driver The piece implemented here is the low-level driver component; there will also be a higher-level buzzer melody player service, to be implemented in RiViera land, that will be the sole caller of PWT API functions provided by the present driver.

# modem services config: voice only
GPRS=0
SRVC=0

# this is a phone handset config
MMI=2
R2D_STATE=1

# small B&W UI version on D-Sample B&W R2D framebuffer
R2D_EMBEDDED_LCD=8
UI_CONFIG=smallbw