NEC V850E/MA1, User Manual

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CHAPTER 12 A/D CONVERTER
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User’s Manual U14359EJ4V0UM
12.4.2 Operation mode and trigger mode
Various conversion operations can be specified for the A/D converter by specifying the operation mode and trigger
mode. The operation mode and trigger mode are set by the ADM0 and ADM1 registers.
The following shows the relationship between the operation mode and trigger mode.
Setting Value Trigger Mode Operation Mode
ADM0 ADM1
Analog Input
1 buffer xx010xxxB 000x0xxxB Select
4 buffers xx110xxxB 000x0xxxB
A/D trigger
Scan xxx00xxxB 000x0xxxB
ANI0 to ANI7
1 buffer xx010xxxB 00100xxxB Select
4 buffers xx110xxxB 00100xxxB
1 trigger
Scan xxx00xxxB 00100xxxB
1 buffer xx010xxxB 00110xxxB Select
4 buffers xx110xxxB 00110xxxB
Timer trigger
4 trigger
Scan xxx00xxxB 00110xxxB
1 buffer xx010xxxB 01100xxxB Select
4 buffers xx110xxxB 01100xxxB
External trigger
Scan xxx00xxxB 01100xxxB
ANI0 to ANI3
(1) Trigger mode
There are three types of trigger modes that serve as the start timing of A/D conversion processing: A/D
trigger mode, timer trigger mode, and external trigger mode. The ANI0 to ANI3 pins are able to specify all of
these modes, but the ANI4 to ANI7 pins can only specify the A/D trigger mode. The timer trigger mode
consists of the 1-trigger mode and 4-trigger mode as the sub-trigger modes. These trigger modes are set by
the ADM1 register.
(a) A/D trigger mode
This mode starts the conversion timing of the analog input set to the ANI0 to ANI7 pins, and by setting
the ADCE bit of the ADM0 register to 1, starts A/D conversion. The ANI4 to ANI7 pins are always set in
this mode.
(b) Timer trigger mode
Specifies the conversion timing of the analog input set for the ANI0 to ANI3 pins using the values set to
the timer C compare register. This mode can only be specified by pins ANI0 to ANI3.
This register creates the analog input conversion timing by generating the match interrupts of the four
capture/compare registers (CCC00, CCC01, CCC10, CCC11) connected to the 16-bit timer C (TMC0,
TMC1).
There are two sub-trigger modes: 1-trigger mode and 4-trigger mode.
•
1-trigger mode
A mode that uses one match interrupt from timer C as the A/D conversion start timing.
•
4-trigger mode
A mode that uses four match interrupts from timer C as the A/D conversion start timing.