Operation Mode Control Circuit; Machine Cycle; Single-Clock Mode - Toshiba TLCS-870/C Series Manual

8 bit microcontroller
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Timing Generator Control Register
7
6
TBTCR
(0036H)
(DVOEN)
(DVOCK)
Selection of input to the 7th stage
DV7CK
of the divider
Note 1: In single clock mode, do not set DV7CK to "1".
Note 2: Do not set "1" on DV7CK while the low-frequency clock is not operated stably.
Note 3: fc: High-frequency clock [Hz], fs: Low-frequency clock [Hz], *: Don't care
Note 4: In SLOW1/2 and SLEEP1/2 modes, the DV7CK setting is ineffective, and fs is input to the 7th stage of the divider.
Note 5: When STOP mode is entered from NORMAL1/2 mode, the DV7CK setting is ineffective during the warm-up period after
release of STOP mode, and the 6th stage of the divider is input to the 7th stage during this period.
2.2.2.2

Machine cycle

Instruction execution and peripheral hardware operation are synchronized with the main system clock.
The minimum instruction execution unit is called an "machine cycle". There are a total of 10 different
types of instructions for the TLCS-870/C Series: Ranging from 1-cycle instructions which require one
machine cycle for execution to 10-cycle instructions which require 10 machine cycles for execution. A
machine cycle consists of 4 states (S0 to S3), and each state consists of one main system clock.
1/fc or 1/fs [s]
Main system clock
State
S0

2.2.3 Operation Mode Control Circuit

The operation mode control circuit starts and stops the oscillation circuits for the high-frequency and low-
frequency clocks, and switches the main system clock. There are three operating modes: Single clock mode,
dual clock mode and STOP mode. These modes are controlled by the system control registers (SYSCR1 and
SYSCR2). Figure 2-6 shows the operating mode transition diagram.
2.2.3.1

Single-clock mode

Only the oscillation circuit for the high-frequency clock is used, and P21 (XTIN) and P22 (XTOUT)
pins are used as input/output ports. The main-system clock is obtained from the high-frequency clock. In
the single-clock mode, the machine cycle time is 4/fc [s].
(1)
NORMAL1 mode
In this mode, both the CPU core and on-chip peripherals operate using the high-frequency clock.
The TMP86PM29BUG is placed in this mode after reset.
5
4
3
2
DV7CK
(TBTEN)
8
0: fc/2
[Hz]
1: fs
S1
S2
S3
Machine cycle
Figure 2-5 Machine Cycle
Page 13
1
0
(TBTCK)
(Initial value: 0000 0000)
S0
S1
S2
TMP86PM29BUG
R/W
S3

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