I've created a custom board based on the ATSAMD21G18A, using the Zero as a base for the variant files and using Martin Lindupp's excellent tutorial as a guide. I have the zero/samd21_sam_ba.bin bootloader flashed, I can upload sketches and my digital pins, USB serial and I2C comms work fine. However, if I try to read an analog pin it crashes the serial comms and the bootloader must be re-flashed (unplugging and reconnecting USB doesn't help - the device doesn't appear in the device manager after reconnection). I'm running a minimal sketch:
int sensorValue = 0;
int delay_ms = 100;
void setup() {
}
void loop() {
// read the value on analog pin:
sensorValue = analogRead(A4);
// blink
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(delay_ms); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(delay_ms);
}
which works fine as long as the analogRead line is commented out. My variant.cpp file looks like this:
#include "variant.h"
/*
typedef struct _PinDescription
{
EPortType ulPort ;
uint32_t ulPin ;
EPioType ulPinType ;
uint32_t ulPinAttribute ;
EAnalogChannel ulADCChannelNumber ; ADC Channel number in the SAM device
EPWMChannel ulPWMChannel ;
ETCChannel ulTCChannel ;
EExt_Interrupts ulExtInt ;
} PinDescription ;
*/
const PinDescription g_APinDescription[]=
{
// 0..11 - Digital pins
// ----------------------
{ PORTA, 19, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_3 },//DOOR 0
{ PORTA, 20, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4}, //EN 1
{ PORTA, 21, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 },//DIN 2
{ PORTA, 16, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_0}, //LED 3
//Not connected
{ PORTA, 17, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_1 }, //2 NC 4
{ PORTA, 18, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 }, //3 NC 5
{ PORTB, 23, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_7 }, //4 NC 6
{ PORTA, 13, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_13}, //5 NC 7
{ PORTB, 22, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, //6 NC 8
{ PORTA, 28, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_8 }, //0 NC 9
{ PORTA, 11, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_11}, //NC 10
{ PORTA, 27, PIO_DIGITAL, (PIN_ATTR_DIGITAL), No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_15 }, //NC 11
// 12..22 - Analogue pins
// --------------------
{ PORTA, 7, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel7, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_7 }, // A1 12
{ PORTA, 6, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel6, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, // A2 13
{ PORTA, 5, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel5, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 }, // A3 14
{ PORTA, 4, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel4, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4 }, // A4 15
{ PORTB, 9, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel3, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_9 }, // A5 16
{ PORTA, 2, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel0, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 }, // A6 17
{ PORTA, 10, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel18, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_10}, //A7 18
{ PORTA, 9, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel17, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_9}, //A8 19
{ PORTA, 8, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel16, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, //A9 20
{ PORTB, 8, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel2, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_8 }, // NC 21
{ PORTB, 2, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel10, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 }, //NC 22
{ PORTA, 22, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // SDA: SERCOM3/PAD[0] 23
{ PORTA, 23, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // SCL: SERCOM3/PAD[1] 24
{ PORTA, 24, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DM 25
{ PORTA, 25, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DP 26
{ PORTA, 3, PIO_ANALOG, PIN_ATTR_ANALOG, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // DAC/VREFP/ 27
{ PORTA, 30, PIO_PWM, PIN_ATTR_DIGITAL|PIO_SERCOM, No_ADC_Channel, NOT_ON_PWM, TCC1_CH0, EXTERNAL_INT_10 }, // SWCLK/ 28
{ PORTA, 31, PIO_PWM, PIN_ATTR_DIGITAL|PIO_SERCOM, No_ADC_Channel, NOT_ON_PWM, TCC1_CH1, EXTERNAL_INT_11 }, // SWDIO/ 29
} ;
extern "C" {
unsigned int PINCOUNT_fn() {
return (sizeof(g_APinDescription) / sizeof(g_APinDescription[0]));
}
}
const void* g_apTCInstances[TCC_INST_NUM+TC_INST_NUM]={ TCC0, TCC1, TCC2, TC3, TC4, TC5 } ;
// Multi-serial objects instantiation
SERCOM sercom0( SERCOM0 ) ;
SERCOM sercom1( SERCOM1 ) ;
SERCOM sercom2( SERCOM2 ) ;
SERCOM sercom3( SERCOM3 ) ;
SERCOM sercom4( SERCOM4 ) ;
SERCOM sercom5( SERCOM5 ) ;
Uart Serial( &sercom5, PIN_SERIAL_RX, PIN_SERIAL_TX, PAD_SERIAL_RX, PAD_SERIAL_TX ) ;
void SERCOM5_Handler()
{
Serial.IrqHandler();
}
variant.h like this:
#ifndef _VARIANT_ARDUINO_ZERO_
#define _VARIANT_ARDUINO_ZERO_
// The definitions here needs a SAMD core >=1.6.10
#define ARDUINO_SAMD_VARIANT_COMPLIANCE 10610
/*----------------------------------------------------------------------------
* Definitions
*----------------------------------------------------------------------------*/
/** Frequency of the board main oscillator */
#define VARIANT_MAINOSC (32768ul)
/** Master clock frequency */
#define VARIANT_MCK (48000000ul)
/*----------------------------------------------------------------------------
* Headers
*----------------------------------------------------------------------------*/
#include "WVariant.h"
#ifdef __cplusplus
#include "SERCOM.h"
#include "Uart.h"
#endif // __cplusplus
#ifdef __cplusplus
extern "C"
{
#endif // __cplusplus
/*----------------------------------------------------------------------------
* Pins
*----------------------------------------------------------------------------*/
// Number of pins defined in PinDescription array
#ifdef __cplusplus
extern "C" unsigned int PINCOUNT_fn();
#endif
#define PINS_COUNT (PINCOUNT_fn())
#define NUM_DIGITAL_PINS (12u)
#define NUM_ANALOG_INPUTS (11u)
#define NUM_ANALOG_OUTPUTS (0u)
#define analogInputToDigitalPin(p) ((p < 12u) ? (p) + 12u : -1)
#define digitalPinToPort(P) ( &(PORT->Group[g_APinDescription[P].ulPort]) )
#define digitalPinToBitMask(P) ( 1 << g_APinDescription[P].ulPin )
//#define analogInPinToBit(P) ( )
#define portOutputRegister(port) ( &(port->OUT.reg) )
#define portInputRegister(port) ( &(port->IN.reg) )
#define portModeRegister(port) ( &(port->DIR.reg) )
#define digitalPinHasPWM(P) ( g_APinDescription[P].ulPWMChannel != NOT_ON_PWM || g_APinDescription[P].ulTCChannel != NOT_ON_TIMER )
//digital pins
#define PIN_DOOR (0u)
#define PIN_EN (1u)
#define PIN_DIN (2u)
#define LED_BUILTIN (3u)
static const uint8_t D0 = PIN_DOOR;
static const uint8_t D1 = PIN_EN;
static const uint8_t D2 = PIN_DIN;
static const uint8_t D3 = LED_BUILTIN;
/*
* Analog pins
*/
#define PIN_A1 (12ul)
#define PIN_A2 (13ul)
#define PIN_A3 (14ul)
#define PIN_A4 (15ul)
#define PIN_A5 (16ul)
#define PIN_A6 (17ul)
#define PIN_A7 (18ul)
#define PIN_A8 (19ul)
#define PIN_A0 (20ul)
//#define PIN_DAC0 (14ul)
static const uint8_t A1 = PIN_A1;
static const uint8_t A2 = PIN_A2;
static const uint8_t A3 = PIN_A3;
static const uint8_t A4 = PIN_A4;
static const uint8_t A5 = PIN_A5;
static const uint8_t A6 = PIN_A6;
static const uint8_t A7 = PIN_A7;
static const uint8_t A8 = PIN_A8;
static const uint8_t A0 = PIN_A0;
//static const uint8_t DAC0 = PIN_DAC0;
#define ADC_RESOLUTION 12
/*
* Wire Interfaces
*/
#define WIRE_INTERFACES_COUNT 1
#define PIN_WIRE_SDA (23u)
#define PIN_WIRE_SCL (24u)
#define PERIPH_WIRE sercom3
#define WIRE_IT_HANDLER SERCOM3_Handler
static const uint8_t SDA = PIN_WIRE_SDA;
static const uint8_t SCL = PIN_WIRE_SCL;
/*
* SPI Interfaces
*/
#define SPI_INTERFACES_COUNT 0
/*
* USB
*/
//#define PIN_USB_HOST_ENABLE (27ul)
#define PIN_USB_DM (25ul)
#define PIN_USB_DP (26ul)
#define PIN_AREF (27ul)
static const uint8_t AREF = PIN_AREF;
#define PIN_SWCLK (28ul)
#define PIN_SWDIO (29ul)
static const uint8_t SWCLK = PIN_SWCLK;
static const uint8_t SWDIO = PIN_SWDIO;
#define PIN_SERIAL_RX (31ul)
#define PIN_SERIAL_TX (30ul)
#define PAD_SERIAL_TX (UART_TX_PAD_2)
#define PAD_SERIAL_RX (SERCOM_RX_PAD_3)
#define PIN_ATN (38ul)
static const uint8_t ATN = PIN_ATN;
#ifdef __cplusplus
}
#endif
/*----------------------------------------------------------------------------
* Arduino objects - C++ only
*----------------------------------------------------------------------------*/
#ifdef __cplusplus
/* =========================
* ===== SERCOM DEFINITION
* =========================
*/
extern SERCOM sercom0;
extern SERCOM sercom1;
extern SERCOM sercom2;
extern SERCOM sercom3;
extern SERCOM sercom4;
extern SERCOM sercom5;
extern Uart Serial;
//extern Uart Serial1;
#endif
#ifdef __cplusplus
extern "C" {
#endif
unsigned int PINCOUNT_fn();
#ifdef __cplusplus
}
#endif
#define SERIAL_PORT_USBVIRTUAL SerialUSB
#define SERIAL_PORT_MONITOR Serial
#endif
Can anyone suggest how to get my analog readings working?
Thanks in advance.