自分用のメモです。
参考HP
https://seeedjp.github.io/Wiki/Document_Guide/XIAO
https://wiki.seeedstudio.com/Seeeduino-XIAO/
ハード
CPU: ARM® Cortex®-M0+ 32bit 48MHz microcontroller(SAMD21G18) with 256KB Flash,32KB SRAM.
3.3V以上電圧を印加しないこと
全部割り込みできるけど5 pin and 7 pinは同時には無理。
const PinDescription g_APinDescription[]=
{
// 0..10 - Digitabl & Analog pins
{ PORTA, 2, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel0, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 }, // ADC/AIN[0]
{ PORTA, 4, PIO_ANALOG, (PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel4, PWM0_CH0, TCC0_CH0, EXTERNAL_INT_4 }, // ADC/AIN[4]
{ PORTA, 10, PIO_ANALOG, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel18, PWM1_CH0, TCC1_CH0, EXTERNAL_INT_10 },
{ PORTA, 11, PIO_ANALOG, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel19, PWM1_CH1, TCC1_CH1, EXTERNAL_INT_11 },
// 4..5 - I2C SERCOM2
{ PORTA, 8, PIO_SERCOM_ALT, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel16, PWM0_CH0, TCC0_CH0, EXTERNAL_INT_NMI }, // SDA: SERCOM2/PAD[0]
{ PORTA, 9, PIO_SERCOM_ALT, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel17, PWM0_CH1, TCC0_CH1, EXTERNAL_INT_9 }, // SCL: SERCOM2/PAD[1]
// 6..7 - UART SERCOM4
{ PORTB, 8, PIO_SERCOM_ALT, (PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel2, PWM4_CH0, TC4_CH0, EXTERNAL_INT_8 }, // TX: SERCOM4/PAD[0]
{ PORTB, 9, PIO_SERCOM_ALT, (PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel3, PWM4_CH1, TC4_CH1, EXTERNAL_INT_9 }, // RX: SERCOM4/PAD[1]
// 8..10 - SPI SERCOM0
{ PORTA, 7, PIO_SERCOM_ALT, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel7, PWM1_CH1, TCC1_CH1, EXTERNAL_INT_7 }, // SCK: SERCOM0/PAD[3]
{ PORTA, 5, PIO_SERCOM_ALT, (PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel5, PWM0_CH1, TCC0_CH1, EXTERNAL_INT_5 }, // MISO: SERCOM0/PAD[1]
{ PORTA, 6, PIO_SERCOM_ALT, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel6, PWM1_CH0, TCC1_CH0, EXTERNAL_INT_6 }, // MOSI: SERCOM0/PAD[2]
// 11..13 - LED
{ PORTA, 19, PIO_TIMER_ALT, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER_ALT), No_ADC_Channel, PWM0_CH3, TCC0_CH3, EXTERNAL_INT_3 }, // TCC0/WO[3]
{ PORTA, 18, PIO_TIMER, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), No_ADC_Channel, PWM3_CH0, TC3_CH0, EXTERNAL_INT_2 }, // TC3/WO[0]
{ PORTA, 17, PIO_PWM, (PIN_ATTR_DIGITAL|PIN_ATTR_PWM|PIN_ATTR_TIMER), No_ADC_Channel, PWM2_CH1, TCC2_CH1, EXTERNAL_INT_1 }, // TCC2/WO[1]
// 14..16 - USB
// --------------------
{ PORTA, 28, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB Host enable
{ PORTA, 24, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DM
{ PORTA, 25, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE } // USB/DP
} ;
ソフト（Arduino）
ADのデフォルトのリファレンスが？3.15Vぐらい？
正確なのは１Vにする方が無難。analogReference(AR_INTERNAL1V0);
switch (mode)
{
case AR_INTERNAL2V23:
ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_1X_Val; // Gain Factor Selection
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INTVCC0_Val; // 1/1.48 VDDANA = 1/1.48* 3V3 = 2.2297
break;
case AR_EXTERNAL:
ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_1X_Val; // Gain Factor Selection
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_AREFA_Val;
break;
case AR_INTERNAL1V0:
ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_1X_Val; // Gain Factor Selection
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INT1V_Val; // 1.0V voltage reference
break;
case AR_INTERNAL1V65:
ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_1X_Val; // Gain Factor Selection
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INTVCC1_Val; // 1/2 VDDANA = 0.5* 3V3 = 1.65V
break;
case AR_DEFAULT:
default:
ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_DIV2_Val;
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INTVCC1_Val; // 1/2 VDDANA = 0.5* 3V3 = 1.65V
break;
}