M37544 RENESAS [Renesas Technology Corp], M37544 Datasheet - Page 37

• Manufacturer Part Number: M37544
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: RENESAS [Renesas Technology Corp]

Rev.1.04
REJ03B0012-0104Z
7544 Group
The oscillation stop detection circuit is used for reset occurrence
when a ceramic resonator or an oscillation circuit stops by discon-
nection. When internal reset occurs, reset because of oscillation
stop can be detected by setting “1” to the oscillation stop detection
status bit.
Also, when using the oscillation stop detection circuit, an on-chip
oscillator is required.
Figure 48 shows the state transition.
The oscillation stop detection status bit retains “1”, not initialized,
when the oscillation stop reset occurs. The oscillation stop detec-
tion status bit is initialized to “0” when the external reset occurs.
Accordingly, reset by oscillation stop can be confirmed by using
this bit.
• Oscillation stop detection status bit is initialized by the following
• The oscillation stop detection circuit is not included in the emu-
Notes on Oscillation Stop Detection Circuit
operation.
(1) External reset
(2) Write “0” data to the ceramic or RC oscillation stop detection
function active bit.
lator MCU “M37544RSS”.
Oscillation stop detection circuit
2004.06.08
page 37 of 66
Fig. 45 Structure of MISRG
b7
b0
Reserved bits (return “0” when read)
(Do not write “1” to these bits)
Oscillation stop detection status bit
0: Oscillation stop not detected
1: Oscillation stop detected
Oscillation stabilization time set bit after
release of the STP instruction
Ceramic/quartz-crystal or RC oscillation
stop detection function active bit
0: Detection function inactive
1: Detection function active
Disable (return “0” when read)
0: Set “01
1: Not set automatically
MISRG(address 0038
in prescaler 1 automatically
16
” in timer1, and “FF
16
, initial value: 00
16
”
16
)