Start Conversion On External Event; Figure 28. Discontinuous Conversion Mode - Holtek HT32F52220 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F52220/HT32F52230
Discontinuous Conversion Mode
(ex: Sequence Length=8, Subgroup Length=3 )
CH2 CH4
Subgroup 0
Start of
Conversion
Single sample
End of
Conversion
Subgroup End
of Conversion
Cycle End of
Conversion

Figure 28. Discontinuous Conversion Mode

Start Conversion on External Event

An A/D converter conversion can be initiated by a software trigger, a General-Purpose Timer
Module (GPTM) event, a Basic Function Timer Module (BFTM) event or an external trigger. Each
trigger source can be enabled by setting the corresponding enable control bit in the ADCTCR
register and then selected by configuring the associated selection bits in the ADCTSR register to
start a group channel conversion.
An A/D converter conversion can be started by setting the software trigger bit, ADSC, in the
ADCTSR register for the group channel when the software trigger enable bit, ADSW, in the
ADCTCR register is set to 1. After the A/D converter starts converting the analog data, the
corresponding enable bit ADSC will be cleared to 0 automatically.
The A/D converter can also be triggered to start a group conversion by a TM event. The TM events
include a GPTM master trigger output MTO, four GPTM channel outputs CH0~CH3 and a BFTM
trigger output. If the corresponding Timer trigger enable bit is set to 1 and the trigger output or the
TM channel event is selected via the relevant TM event selection bits, the A/D converter will start
a conversion when a rising edge of the selected trigger event occurs.
In addition to the internal trigger sources, the A/D converter can be triggered to start a conversion
by an external trigger event. The external trigger event is derived from the external lines, EXTIn.
If the external trigger enable bit ADEXTI is set to 1 and the corresponding EXTI line is selected by
configuring the ADEXTIS field in the ADCTSR register, the A/D converter will start a conversion
when an EXTI line active edge determined in the EXIT Unit occurs.
Rev. 1.10
Cycle
CH7 CH5 CH6 CH3
Subgroup 1
157 of 366
CH0 CH1 CH2 CH4
Subgroup 2 Subgroup 0
November 09, 2018
Cycle
CH7