Maxim Integrated High-Speed Microcontroller - Manual (Page 92)

High-Speed Microcontroller User’s Guide
Rev: 062210 92 of 176
EXIF .2: Ring Oscillator Mode (RGMD). Hardware will set this status bit to a 1 when the clock source
is the ring oscillator. Hardware will set this status bit to a 0 when the crystal is the clock source. Refer to
RGSL below for operation of the ring oscillator.
EXIF .1: Ring Oscillator Select (RGSL). When set to a 1 by software, the high-speed microcontroller
will use a ring oscillator to come out of Stop mode without waiting for crystal startup. This allows an
instantaneous startup when coming out of Stop mode. It is useful if software needs to perform a short
task, then return
to Stop. It is also useful if software must respond quickly to an external event. After the
crystal has performed 65,536 cycles, hardware will switch to the crystal as its clock source. The RGMD
status bit reports on this changeover. When RGSL is set to a 0, the high-speed microcontroller will delay
software execution until after the 65,536 clock crystal startup time. RGSL is only cleared by a power-on
reset and is not altered by other forms of reset.
EXIF .0: Bandgap Select (BGS). Setting this bit to a 1 will allow the use of the bandgap voltage
reference while in Stop mode. Since this function uses as much as 50mA, the bandgap is optional in Stop
mode. Setting this bit to a 0 will turn off the bandgap while in Stop mode. When BGS = 0, no power-fail
interrupt or power-fail reset will be available in Stop mode.
PCON .1: Stop Mode Select (STOP). When this bit is set, the program stops execution, clocks are
stopped, and the CPU enters power-down mode.
PCON. 0: Idle Mode Select (IDLE). Program execution halts leaving timers, serial ports, and clocks
running.