Z86E30/E31/E40
Z8 4K OTP Microcontroller
Zilog
SCLK/TCLK Divide-by-16 Select (D0). This bit of the
SMR controls a divide-by-16 prescaler of SCLK/TCLK.
The purpose of this control is to selectively reduce device
power consumption during normal processor execution
(SCLK control) and/or HALT mode (where TCLK sources
counter/timers and interrupt logic).
PCON further helps lower EMI (i.e., D7 (PCON) = 0, D1
(SMR) = 1). The default setting is zero.
STOP-Mode Recovery Source (D2, D3, and D4). These
three bits of the SMR register specify the wake up source
of the STOP-Mode Recovery (Figure 32). Table 12 shows
the SMR source selected with the setting of D2 to D4. P33-
P31 cannot be used to wake up from STOP mode when
programmed as analog inputs. When the STOP-Mode Re-
covery sources are selected in this register then SMR2
register bits D0, D1 must be set to zero.
1
External Clock Divide-by-Two (D1). This bit can elimi-
nate the oscillator divide-by-two circuitry. When this bit is
0, the System Clock (SCLK) and Timer Clock (TCLK) are
equal to the external clock frequency divided by two. The
SCLK/TCLK is equal to the external clock frequency when
this bit is set (D1=1). Using this bit together with D7 of
Note:If the Port2 pin is configured as an output, this output
level will be read by the SMR circuitry..
SMR2 D1 D0
0
0
SMR2 D1 D0
SMR2 D1 D0
VDD
0
1
1
0
P20
P23
P20
P27
SMR D4 D3 D2
0
0
0
SMR D4 D3 D2 SMR D4 D3 D2 SMR D4 D3 D2
SMR D4 D3 D2
SMR D4 D3 D2
VDD
0
0
0
0
1
1
1
0
1
1
0
0
1
0
1
1
1
0
1
1
1
P20
P20
P30
P31
P32
P33
P27
P23
P27
To POR
RESET
Stop-Mode Recovery Edge
Select (SMR)
To P33 Data
Latch and IRQ1
MUX
P33 From Pads
Digital/Analog Mode
Select (P3M)
Figure 32. STOP-Mode Recovery Source
DS97Z8X0500
P R E L I M I N A R Y
45
ZILOG [ ZILOG, INC. ]
