M16C1N Datasheet, PDF (48/238 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/10 SERIES

M16C/1N Group
6. Clock Generation Circuit
6.6 Oscillation Stop Detection Function
The oscillation stop detection function detects abnormal stopping of the main clock by causes such as
opening and shorting of the XIN oscillation circuit. When oscillation stop is detected, an oscillation stop
detection interrupt is issued. When an oscillation stop detection interrupt is issued, the on-chip oscillator
in the microcomputer operates automatically and is used as the main clock in place of the XIN clock. This
allows interrupt processing.
The oscillation stop detection function can be enabled/disabled with bit 0 and bit 1 of the oscillation stop
detection register. When this bit is set to "112", the function is enabled. After the reset is released, the
oscillation stop detection function becomes disabled because the bit value is "002".
Table 6.5 lists the specification of oscillation stop detection function, Figure 6.10 shows a configuration
diagram of the oscillation stop detection circuit and Figure 6.11 shows the configuration of the oscillation
stop detection register.
Table 6.5 Specification overview of the oscillation stop detection function
Item
Specification
Oscillation stop detectable clock and XIN ≥ 2 MHz
frequency bandwidth
Enabling condition for oscillation stop When the oscillation stop detection bit (bit 0 at address 000C16)
detection function
and the oscillation stop detection interrupt enable bit (bit 1 at
address 000C16) are set to "1"
Operation at oscillation stop detection • Oscillation stop detection interrupt occurs
Notes on STOP mode, low power
Before stopping the main clock (XIN-XOUT), set the
dissipation mode, and on-chip
oscillation stop detection enable bit to "0" to disable the
oscillator mode
oscillation stop detection function. Enable main clock
(XIN-XOUT) oscillation and after the oscillation stabilizes,
set the bit to "1" again.
Notes on WAIT mode
If the peripheral function clock is stopped in WAIT mode
with the WAIT mode peripheral function clock stop bit
(bit 2 at address 000616), oscillation stop will be detected.
Do not stop the peripheral function clock in WAIT mode.
Rev.1.00 Oct 20, 2004 page 36 of 222
REJ09B0007-0100Z