6

MITSUBISHI MICROCOMPUTERS

M37733EHBXXXFP

M37733EHBFS

PROM VERSION OF M37733MHBXXXFP

PRELIMINAR

Y

Notice:

This

is not

a final

specification.

Some

parametric

limits

are

subject

to change.

BASIC FUNCTION BLOCKS

The M37733EHBXXXFP has the same functions as the

M37733MHBXXXFP except for the following:

(1) The built-in ROM is PROM.

(2) The status of bit 3 of the oscillation circuit control register 1 (address

(3) The usage condition of bit 3 of the oscillation circuit control register

1 is different.

Accordingly, refer to the basic function blocks description in the

M37733MHBXXXFP except for Figure 1 (bit configuration of the

oscillation circuit control register 1) and Figure 3 (microcomputer

internal status during reset).

In the M37733EHBXXXFP, bit 3 of the oscillation circuit control

register 1 must be “1”. (Refer to Figure 1.) The status of this bit at

a reset is “1”.

Fig. 2 How to write data in oscillation circuit control register 1 (identical with Figure 64 in data sheet “M37733MHBXXXFP”)

Reset clock prescaler

• How to reset clock prescaler

Note. “Y” is the sum of bits to be set. For example, when

setting bits 2 and 1 to “1”, “Y” becomes “6”.

Next instruction

Note. Write to the oscillation circuit control

register 1 as the flow shown in Figure 2.

Oscillation circuit control register 1

Main clock division selection bit

0 : Main clock is divided by 2.

1 : Main clock is not divided by 2.

Main clock external input selection bit

0 : Main-clock oscillation circuit is operating by itself.

Watchdog timer is used at returning from STP state.

1 : Main-clock is input externally.

Watchdog timer is not used at returning from STP state.

Sub clock external input selection bit

0 : Sub-clock oscillation circuit is operating by itself.

Watchdog timer is used at returning from STP state.

1 : Sub-clock is input externally.

Watchdog timer is not used at returning from STP state.

1 : Always “1” (“1” at reset)

Clock prescaler reset bit

Address

0

76543

2

1

0

1

Fig. 1 Bit configuration of oscillation circuit control register 1 (corresponding to Figure 63 in data sheet “M37733MHBXXXFP”)