![](http://datasheet.mmic.net.cn/120000/M37920FCCHP_datasheet_3558847/M37920FCCHP_68.png)
M37920FCCGP, M37920FCCHP
M37920FGCGP, M37920FGCHP
PRELIMINAR
Y
Notice:
This
is not
a final
specification.
Some
parametric
limits
are
subject
to change.
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER FLASH MEMORY VERSION
MITSUBISHI MICROCOMPUTERS
68
Trigger
A-D conversion can be started by software trigger or by an external
input trigger.
Software trigger is selected when bit 5 of A-D control register 0 is “0”
and an external trigger is selected when it is “1”. When a software
trigger is selected, A-D conversion is started when bit 6 (A-D conver-
sion start bit) is set to “1.”
When an external trigger is selected, the polarity of a trigger input
can be selected by bit 5 of the A-D control register 1. When bit 5 =
“0”, a falling edge is selected, and when bit 5 = “1”, a rising edge is
selected.
A-D conversion starts when the A-D conversion start bit is “1” and the
ADTRG input changes from “H” to “L” (or “L” to “H.”) In this case, the
pins that can be used for A-D conversion are AN0 to AN2 because the
ADTRG pin is multiplexed with an analog voltage input pin, AN3. If an
Fig. 64 Bit configuration of A-D control register 0
external trigger is selected, even when the A-D conversion is com-
pleted, the A-D conversion start bit keeps “1”. Also, a retrigger can be
available even when A-D conversion is in progress.
VREF connection
Whether to connect the reference voltage input (VREF) with the resis-
tor ladder network or not depends on bit 6 of the A-D control register
1. The VREF pin is connected when bit 6 is “0” and is disconnected
when bit 6 is “1” (High impedance state).
When A-D conversion is not performed, current from the VREF pin to
the resistor ladder network can be cut off by disconnecting resistor
ladder network from the VREF pin.
Before starting A-D conversion, wait for 1
s or more after clearing
bit 6 to “0”.
A-D control register 0
Address
1E16
76543210
Analog input select bits
(Valid in the one-shot and repeat modes.)
0 0 : Select AN0
0 1 : Select AN1
1 0 : Select AN2
1 1 : Select AN3
Must be “0”.
A-D operation mode select bits
0 0 : One-shot mode
0 1 : Repeat mode
1 0 : Single sweep mode
1 1 : Repeat sweep mode
Trigger select bit
0 : Software trigger
1 : External trigger due to ADTRG input
A-D conversion start bit (Note 7)
0 : Stop A-D conversion
1 : Start A-D conversion
A-D conversion frequency (
φAD) select bit 0
0
76543210
A-D sweep pin select bit
(Valid in the single sweep mode and repeat sweep mode.)
0 : AN0, AN1
1 : AN0–AN3
Must be “0”.
Resolution select bit
0: 8-bit mode
1: 10-bit mode
A-D conversion frequency (
φAD) select bit 1
External trigger polarity select bit
(Valid when external trigger is selected.)
0: Falling edge
1: Rising edge
VREF connection select bit
0 : VREF is connected.
1 : VREF is not connected.
“0” at read.
(2 pins)
(4 pins)
A-D control register 1
Address
1F16
A-D conversion frequency (
φAD) select bit
Bit 1
0
1
0
1
Bit 0
φAD
f2/4
f2/2
f2
1
f1 (Selectable only in 8-bit mode)
0