25 A/D CONVERTER (ADC10)
25-4
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
A/D Conversion Mode Setting
25.3.3
The A/D converter provides two conversion modes that can be selected using ADMS/ADC10_TRG register: one-
time conversion mode and continuous conversion mode.
1. One-time conversion mode (ADMS = 0)
The A/D converter performs A/D conversion for all analog inputs within the range from the start channel speci-
fied by ADCS[2:0]/ADC10_TRG register to the end channel specified by the ADCE[2:0]/ADC10_TRG register
once and then stops automatically.
2. Continuous conversion mode (ADMS = 1)
The A/D converter repeatedly performs A/D conversion for the channels in the range specified by ADCS[2:0]
and ADCE[2:0] until stopped with software.
At initial reset, the A/D converter is set to one-time conversion mode.
Trigger Selection
25.3.4
Select a trigger source to start A/D conversion from among the three types listed in Table 25.3.4.1 using ADTS[1:0]/
ADC10_TRG register.
3.4.1 Trigger Selection
Table 25.
ADTS[1:0]
Trigger source
0x3
External trigger (#ADTRIG)
0x2
Reserved
0x1
T8 Ch.2
0x0
Software trigger
(Default: 0x0)
1. External trigger (#ADTRIG)
The signal input to the #ADTRIG pin is used as a trigger. To use this trigger source, the I/O port pin must be
configured for the #ADTRIG input using the port function select bit (see the “I/O Ports (GPIO)” chapter). An
A/D conversion starts when a Low level of the #ADTRIG signal is detected.
Note: When using an external trigger to start A/D conversion, ensure to maintain the Low period of the
trigger signal input to the #ADTRIG pin for two or more C33 PE Core operating clock cycles.
2. T8 Ch.2
The underflow signal of T8 Ch.2 is used as a trigger. Since T8 underflow cycle can be programmed with flex-
ibility, this trigger source is effective when periodic A/D conversions are required. For more information on
timer settings, see the “8-bit Timers (T8)” chapter.
3. Software trigger
Writing 1 to ADCTL/ADC10_CTL register with software serves as a trigger to start A/D conversion.
Sampling Time Setting
25.3.5
The analog signal input sampling time in this A/D converter is configured with ADST[2:0]/ADC10_TRG register.
In the S1C33L26, do not alter ADST[2:0] from the default value (0x7).