Why does Arduino digitalWrite not work with pin3?

Development Boards Artemis
1

Using the latest Artemis Arduino version, the following code toggles pin 19 but not pin 3:

//digitalWrite does not work with pin3 but it does with pin19
void setup() {
  pinMode(3, OUTPUT);
  pinMode(19, OUTPUT);
}

void loop() {
    digitalWrite(19, HIGH);
    digitalWrite(3, HIGH);
    delay(1000);
    digitalWrite(19, LOW);
    digitalWrite(3, LOW);
    delay(1000);
}

If this is rewritten as follows using the native gpio, pin 3 toggles fine.

#include <am_hal_gpio.h>
// This works, both pins 3 and 19 toggle as expected
void setup() {
    am_hal_gpio_pinconfig(3, g_AM_HAL_GPIO_OUTPUT);
    am_hal_gpio_pinconfig(19, g_AM_HAL_GPIO_OUTPUT);
    am_hal_gpio_output_set(3);
    am_hal_gpio_output_set(19);
}

void loop() {
    am_hal_gpio_output_toggle(3);
    am_hal_gpio_output_toggle(19);
    delay(1000);
    am_hal_gpio_output_toggle(3);
    am_hal_gpio_output_toggle(19);
    delay(1000);
}
2

which Artemis board did you use ?

3

MicroMod Artemis

4

Thanks.

On a Micromod Artemis “3” or “D3” can be used to perform a 3v3_en signal. On the Micromod Motherboard, there is an (open) VE or EN-jumper (depending on the Micromod motherboard) to make the hardware connection. It feels like a catch-22 as when the processor disables the 3v3… it also disables the power to the processor.?? As this is a special it is NOT defined in the variantPinStates-structure for the micromod Artemis. This structure, defined for each variant, is used for look-up in case of pin mode & digitalWrite & digitalRead. Hence it does not work.

5

Thanks. I thought it might be something to do with the variants. I am using the Artemis on a custom board and so I did not pay attention to the SparkFun main board use case but that makes sense.

6

I swapped to the Artemis Module board and that fixed the issue because the Variant file includes pin3.

7

correct !.. it only just does not contain Pin 30…