Operation - Toshiba TLCS-90 Series Data Book

TOSHIBA
ADREG
(FFEEH)
MSB
7 6
5 4 3 2
LSB
o
AID conversion result register (Read only)
Fig. 3.9 (3) AID Conversion Result Register
TMP90C840
3.9.2 Operation
(1) Analog reference voltage
The high analog reference voltage is applied to the VREF pin, and the
low analog reference voltage is applied to the AGND pin.
The reference voltage between VREF and AGND is divided by 2S6 by
connecting ladder resistance, and compared with the analog input
voltage for
AID
conversion.
(2) Analog input channels
For the AI D convers ion, one of the six ana log input channe Is (ANO
(PSO) to
&~S
(PSS» is selected by the register ADMOD2-0 (ADCH).
ADCH is initialized to "000" by resetting, whereby the ANO pin
18
selected.
The pins not used for the analog input can be used for ordinary input
(PS).
(3) Selection of
AID
conversion speed
Normally, the AID converter is used in the high-speed conversion mode
that completes the operation in 95 states (19
~s
@fc=lOMHz).
When using an oscillation frequency of more than 10MHz, set the
register ADMOD4 (ADes) to "1" and obtain the conversion speed of 190
states (38
~s,
@fc=10MHz).
ADCS is initialized to "0" by resetting, by which the
AID
converter
turns to the high-speed conversion mode.
(4) Starting
AID
conversion
The
AID
conversion is started by writing "1" into the register ADMOD3
(ADS). When the
AID
conversion is started, the ADMODS (ADBF) flag is
set to "1", indicating that the conversion is in progress.
(S)
AID
conversion end and interrupt
When the
AID
conversion is completed, the ADMOD6 (EOCF) flag is set to
"1", indicating that the
AID
conversion is completed. Then the ADBF
flag is cleared to "0" to generate the interrupt INTAD.
INTAD (interrupt by the
AID
converter) is controlled by the interrupt
enab Ie flag INTEL 7 (IET2), also used for INTT2 (interrupt by Timer
2). Either INTAD or INTT2 is selected by the INTER3 (ADIS) flag. To
generate INTAD interrupt, both IET2 and ADIS should be set to "1".
Both INTAD and INTT2 jump to the same vector address (0040H), but can
be distinguished by the ADIS flag.
When IN TAD is latched, the INTAD status cannot be cleared by software.
MPU90-127