deveopmen
Rev.B2 for proof reading
A-D Converter
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
292
(a) Resolution select function
8/10-bit mode select bit of A-D control register 1 (bit 3 at address 0397
16
, 01D7
16
)
When set to 10-bit precision, the low 8 bits are stored in the even addresses and the high 2 bits in the odd
addresses. When set to 8-bit precision, the low 8 bits are stored in the even addresses.
(b) Sample and hold
Sample and hold are selected by setting bit 0 of the A-D control register 2 (address 0394
16
, 01D4
16
) to
“
1
”
. When sample and hold are selected, the rate of conversion of each pin increases. As a result, a 28
AD
cycle is achieved with 8-bit resolution and 33
AD
with 10-bit resolution. Sample and hold can be
selected in all modes. However, in all modes, be sure to specify before starting A-D conversion whether
sample and hold are to be used.
(c) Trigger select function
Can appoint start of conversion, by a combination of setting of trigger select bit (bit 5 at address 0396
16
,
01D6
16
) and external trigger request cause select bit (bit 5 and bit 6 at address 0394
16
, 01D4
16
), as
follows.
Table 1.24.7. Trigger select function setting
Trigger select bit="1"
Trigger select bit=
"0"
External trigger cause select bits
00
01
10
A-D0
Software trigger
AD
TRG
Timer B2 OFCOI
(Note)
Group 2 channel 1 interrupt
A-D1
Software trigger
AD
TRG
Timer B2 OFCOI
(Note)
Group 3 channel 1 interrupt
Timer B2 OFCOI : Timer B2 occurrence frequency counter overflow interrupt
Note :Valid in three-phase PWM mode.
(d) Two circuit same time start (software trigger)
Two A-D converters can start at the same time by setting simultaneous start bit (bit 7 of address 0394
16
)
to
“
1
”
.
During the A-D circuit of either of A-D0 and A-D1 are operated, do not set
“
1
”
to the simultaneous start bit.
Do not set to "1" when external trigger is selected. When using this bit, do not set A-D conversion start
flag (bit 6 of address 0396
16
, 01D6
16
) to "1".
(e) Replace function of input pin
Setting "1" to A-D channel replace select bit of A-D0 control register 2 (ADS:bit 4 at address 0394
16
) can
replace channel of A-D0 and A-D1. A-D conversion reliability is confirmed by replacing channels.
When ADS bit is "1", a corresponding pin of A-D0 register i is selected by analog input port select bits of
A-D1 control register 2 (bits 2 and 1 at address 01D4
16
). In this case, A-D0 control register 0 and A-D1
control register 0 must be set to same value.