h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 507

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

• Clearing with the RES pin
• Clearing with the STBY pin
Setting Oscillation Stabilization Time after Clearing Software Standby Mode: Bits STS2 to
STS0 in SBYCR should be set as described below.
• Using a crystal resonator
• Using an external clock
Table 16.2 Operating Frequency and Standby Time
Note:
Software Standby Mode Application Example: Figure 16.2 shows an example in which a
transition is made to software standby mode at the falling edge on the NMI pin, and software
standby mode is cleared at the rising edge on the NMI pin.
In this example, an NMI interrupt is accepted with the NMIEG bit in SYSCR cleared to 0 (falling
edge specification), then the NMIEG bit is set to 1 (rising edge specification), the SSBY bit is set
to 1, and a SLEEP instruction is executed, causing a transition to software standby mode.
Software standby mode is then cleared at the rising edge on the NMI pin.
STS2
0
1
When the RES pin is driven low, clock oscillation is started. At the same time as clock
oscillation starts, clocks are supplied to the entire LSI. Note that the RES pin must be held low
until clock oscillation stabilizes. When the RES pin goes high, the CPU begins reset exception
handling.
When the STBY pin is driven low, a transition is made to hardware standby mode.
Set bits STS2 to STS0 so that the standby time is more than the oscillation stabilization time.
Table 16.2 shows the standby times for operating frequencies and settings of bits STS2 to
STS0.
A PLL circuit stabilization time is necessary. Refer to table 16.2 to set the standby time.
: Recommended setting time
*
STS1
0
1
0
1
This setting must not be used in the flash memory version.
STS0
0
1
0
1
0
1
0
1
Standby Time
8192 states
16384 states
32768 states
65536 states
131072 states
262144 states
Reserved
16 states*
10 MHz
0.8
1.6
3.2
6.5
13.1
26.2

1.6
20 MHz
0.4
0.8
1.6
3.2
6.5
13.1

0.8
Rev. 2.00, 03/04, page 475 of 534
33 MHz
0.2
0.4
0.9
1.9
3.9
7.9

0.4
Unit
ms

µs