2.1. ADC12

2.1.1. Overview

This example shows ADC12 conversions and results in four working modes.

Notes:

• When ADC is configured to non-bus-read (oneshot) mode, it can’t be accessed otherwise bus will be stuck.

• When ADC is configured to bus-read (oneshot) mode, CPU has to complete initialization before accessing to the ADC register list.

2.1.2. Board Setting

Input voltage at the specified pin. （Please refer to Pin Description ）

Note: The input voltage range at ADC input pins: 0~VREFH

2.1.3. Running the example

• Running log is shown in the serial terminal as follows

  This is an ADC12 demo:
  1. Oneshot    mode
  2. Period     mode
  3. Sequence   mode
  4. Preemption mode
  Please enter one of ADC conversion modes above (e.g. 1 or 2 ...):
  

• Select one of ADC working modes to start ADC conversion, and then watch conversion results

  • Oneshot mode

    Please enter one of ADC conversion modes above (e.g. 1 or 2 ...): 1
    Oneshot Mode - ADC0 [channel 11] - Result: 0x0ffb
    Oneshot Mode - ADC0 [channel 11] - Result: 0x0ffb
    Oneshot Mode - ADC0 [channel 11] - Result: 0x0ffb
    

  • Period mode

    Please enter one of ADC conversion modes above (e.g. 1 or 2 ...): 2
    Period Mode - ADC0 [channel 11] - Result: 0x0ffb
    Period Mode - ADC0 [channel 11] - Result: 0x0fff
    Period Mode - ADC0 [channel 11] - Result: 0x0ffd
    

  • Sequence mode

    Please enter one of ADC conversion modes above (e.g. 1 or 2 ...): 3
    Sequence Mode - ADC0 - Cycle Bit: 01 - Sequence Number:00 - ADC Channel: 11 - Result: 0x0fff
    Sequence Mode - ADC0 - Cycle Bit: 00 - Sequence Number:00 - ADC Channel: 11 - Result: 0x0ffb
    Sequence Mode - ADC0 - Cycle Bit: 01 - Sequence Number:00 - ADC Channel: 11 - Result: 0x0ff7
    

  • Preemption mode

    Please enter one of ADC conversion modes above (e.g. 1 or 2 ...): 4
    Preemption Mode - ADC0 - Trigger Channel: 11 - Cycle Bit: 01 - Sequence Number: 00 - ADC Channel: 11 - Result: 0x0ff9
    Preemption Mode - ADC0 - Trigger Channel: 11 - Cycle Bit: 01 - Sequence Number: 00 - ADC Channel: 11 - Result: 0x0ff9
    Preemption Mode - ADC0 - Trigger Channel: 11 - Cycle Bit: 01 - Sequence Number: 00 - ADC Channel: 11 - Result: 0x0ff9
    

2.1.4. Note

• How to use WDOG feature

  • Channel initialization

    • Set ch_cfg. wdog_int_en to true

    • Set ch_cfg.thshdl/ch_cfg.thshdh

      The ch_cfg.thshdl/ch_cfg.thshdh can be configured from 0 to 4095. If any ADC conversion result is out of the thresholds (thshdl, thsdhh), a WDOG interrupt will occur.

  • Call adc16_init_channel () API.

  • ISR

    • Set one or more WDOG event flags depending on ADC channels

    • Disable one or more corresponding WDOG interrupts

  • Main loop

    • Handle with WDOG events

    • Enable one or more corresponding WDOG interrupts

• Trigger source

  • In this sample, for sequence mode and preemption mode, PWM is selected as the trigger source. Other peripherals can also be selected as the trigger source.

  • The frequency of the trigger signal(20KHz by default) can be configured in sample-level CMakeLists.txt(e.g. sdk_compile_definitions(-DAPP_ADC12_TRIG_SRC_FREQUENCY=20000))

• Exception exit

  Press the “space” key to abort the test, and then a test mode can be reselected.