M37754 Mitsubishi, M37754 Datasheet - Page 57

• Manufacturer Part Number: M37754
• Description: SINGLE-CHIP 16BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

lower, “0” is stored into that register.
Be sure to perform only read to the A-D register of which channel is
selected as an A-D converter, and perform only write to the A-D reg-
ister of which channel is selected as a comparator. Additionally, do
not write to the comparator function select register and the A-D reg-
ister while an A-D converter or a comparator is operating.
Port direction register’s bits corresponding to pins to be A-D con-
verted must be “0” (input mode) because analog input ports are mul-
tiplexed with port P7.
Figure 71 shows the bit configuration of the A-D control register 0
(address 1E
selected with bit 7 of the A-D control register 0 and bit 4 of the A-D
control register 1.
When bit 4 (frequency select flag 1) of the A-D control register 1 is
“0”,
Whether to connect the reference voltage input (V
Figure 69 shows the comparator function select register (address
64
spectively. Each channel can be selected as either an A-D converter
or a comparator. When the bit is “0”, the channel corresponding to it
functions as a 10-bit or an 8-bit A-D converter. When the bit is “1”, the
channel functions as a comparator.
When selecting an A-D converter, an input voltage to a selected ana-
log input pin is A-D converted and the result is stored into the A-D
register.
When selecting a comparator, D-A conversion is performed to the
value of which high-order 8 bits are the value stored in an even ad-
dress of the A-D converter and of which low-order 2 bits are “10
Then, this D-A converted value is compared with the voltage sup-
plied to an analog input pin. After the comparison, when the voltage
supplied to an analog input pin is higher, “1” is stored into the com-
parator result register (address 66
An operation clock (
control register 0 is “0”,
trol register 0 is “1”.
When the frequency select flag 1 is “1”,
frequency select flag 0 is “0”,
select flag 0 is “1”. The last case is used when
lection is available only in 8-bit resolution mode.
comparator uses a capacity coupling amplifier.
Bit 3 of A-D control register 1 is used to select whether to regard the
conversion result as 10-bit or as 8-bit data. The conversion result is
regarded as 10-bit data when bit 3 is “1” and as 8-bit data when bit 3
is “0”.
When the conversion result is used as 10-bit data, the low-order 8
bits of the conversion result is stored in the even address of the cor-
responding A-D register and the high-order 2 bits are stored in bits 0
and 1 at the odd address of the corresponding A-D register. Bits 2 to
7 of the A-D register odd address are “000000
When the conversion result is used as 8-bit data, the high-order 8
bits of the 10-bit A-D conversion result are stored in even address of
the corresponding A-D register. In this case, the value at the A-D
register’s odd address is “00
AD
AD
16
in high-speed running (f(X
during A-D conversion must be 250 kHz or more because the
) bit configuration. Bits 7 to 0 correspond to channels 7 to 0 re-
AD
becomes Pf
16
) and the A-D control register 1 (address 1F
8
AD
when bit 7 (frequency select flag 0) of the A-D
) of an A-D converter or a comparator can be
AD
becomes Pf
16
IN
” when read.
AD
) >
16
becomes
1
) shown in Figure 70. When it is
> 12.5 MHz). However, this se-
4
AD
when bit 7 of the A-D con-
becomes Pf
1
2
” when read.
when the frequency
1
is forcibly used as
REF
M37754M8C-XXXGP, M37754M8C-XXXHP
) with the lad-
2
16
when the
).
2
.”
der network or not depends on bit 5 of the A-D control register 1. The
V
5 is “1” (High impedance state).
When A-D or D-A conversion is not performed, current from the V
pin to the ladder network can be cut off by disconnecting ladder net-
work from the V
Before starting A-D or D-A conversion, wait for 1 s or more after
clearing bit 5 to “0”.
Fig. 69 Comparator function select register bit configuration
Fig. 70 Comparator result register bit configuration
REF
Note: Do not access with the SEB or CLB instruction.
7
M37754S4CGP, M37754S4CHP
7
6
pin is connected when bit 5 is “0” and is disconnected when bit
6
5
5
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
4
4
3
3
REF
2
2
pin.
1
1
MITSUBISHI MICROCOMPUTERS
0
0
Comparator result register
“0” : ANi input level is lower than set digital value
“1” : ANi input level is higher than set digital value
AN
AN
AN
AN
AN
AN
AN
AN
Comparator function select register
“0” : Select A-D converter
“1” : Select comparator
AN
AN
AN
AN
AN
AN
AN
AN
0
1
2
3
4
5
6
7
pin comparator result bit
pin comparator result bit
pin comparator result bit
pin comparator result bit
pin comparator result bit
pin comparator result bit
pin comparator result bit
pin comparator result bit
0
1
2
3
4
5
6
7
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
pin comparator function select bit
Address
66
16
Address
64
16
REF
57