TMPM330 - Keil

13.4 Description of Operations
13.4.1 Analog Reference Voltage
Under development
TMPM330 (rev 0.4)13 -16
TMPM330
The "H" level of the analog reference voltage shall be applied to the VREFH pin, and the
"L" level shall be applied to the VREFL pin. By writing "0" to the ADMOD1 bit,
a switched-on state of VREFH-VREFL can be turned into a switched-off state. To start AD
conversion, make sure that you first write "1" to the bit, wait for 3 μs during
which time the internal reference voltage should stabilize, and then write "1" to the
ADMOD0 bit.
13.4.2 Selecting the Analog Input Channel
How the analog input channel is selected is different depending on A/D converter
operation mode used.
(1) Normal AD conversion mode
• If the analog input channel is used in a fixed state (ADMOD0="0"):
One channel is selected from analog input pins AIN0 through AIN11 by setting
ADMOD1 to an appropriate setting.
• If the analog input channel is used in a scan state (ADMOD0="1"):
One scan mode is selected from 12 scan modes by setting ADMOD1 and
ADSCN to appropriate settings.
(2)Top-priority AD conversion mode
One channel is selected from analog input pins AIN0 through AIN11 by setting
ADMOD2 to an appropriate setting.
After a reset, ADMOD0 is initialized to "0" and ADMOD1 is
initialized to "0000." This initialization works as a trigger to select a fixed channel input
through the AN0 pin. The pins that are not used as analog input channels can be used as
ordinary input ports.
If top-priority AD conversion is activated during normal AD conversion, normal AD
conversion is discontinued, top-priority AD conversion is executed and completed, and
then normal AD conversion is resumed.
Example: A case in which repeat-scan conversion is ongoing at channels AIN0
through AIN3 with ADMOD0 set to "11" and
ADMOD1 set to 0011, and top-priority AD conversion has been
activated at AIN12 with ADMOD2=1100.
Top-priority AD
has been activated
Conversion Ch0 Ch1 Ch2 Ch12 Ch2 Ch3 Ch0
Ch
Analog/ Digital Converter