Quadrature Decoder Failing to build on NCS v2.1

[ArchieA_C]

Hello,

When enabling the Sensor system and having a qdec device enabled in my dts I get the following error:

/home/ee/ncs/zephyr/drivers/sensor/qdec_nrfx/qdec_nrfx.c:98:21: error: expression in static assertion is not constant
   98 |  BUILD_ASSERT(steps > 0, "only positive number valid");
      |               ~~~~~~^~~
/home/ee/ncs/zephyr/drivers/sensor/qdec_nrfx/qdec_nrfx.c:99:21: error: expression in static assertion is not constant
   99 |  BUILD_ASSERT(steps <= 2048, "overflow possible");
      |               ~~~~~~^~~~~~~

This seems to be a bug with the Zephyr code checking a const local var at compile time. Has anyone else had this issue?

Best,

Archie

[Jørgen Holmefjord]

Hi,

You need to configure the QDEC in the devicetree or overlay file for the project, see the example in this post.

Can you check if you still get the build asserts with this set?

Best regards,
Jørgen

[ArchieA_C]

It has been configured as shown below:

&qdec0{
	compatible = "nordic,nrf-qdec";
	status = "okay";
	led-pre = <0>;
	steps = <12>;

	pinctrl-0 = <&qdec0_default>;
	pinctrl-1 = <&qdec0_sleep>;
	pinctrl-names = "default", "sleep";	
};

It seems to be the qdec code that is wrong as it's saying the expression isn't constant.

Modifying the code to this:

static int qdec_nrfx_channel_get(const struct device *dev,
				 enum sensor_channel  chan,
				 struct sensor_value *val)
{
	struct qdec_nrfx_data *data = &qdec_nrfx_data;
	unsigned int key;
	int32_t acc;
	const int32_t steps = DT_INST_PROP(0, steps);

	ARG_UNUSED(dev);
	LOG_DBG("");

	if (chan != SENSOR_CHAN_ROTATION) {
		return -ENOTSUP;
	}

	key = irq_lock();
	acc = data->acc;
	data->acc = 0;
	irq_unlock(key);

	BUILD_ASSERT(DT_INST_PROP(0, steps) > 0, "only positive number valid");
	BUILD_ASSERT(DT_INST_PROP(0, steps) <= 2048, "overflow possible");

	val->val1 = (acc * FULL_ANGLE) / steps;
	val->val2 = (acc * FULL_ANGLE) - (val->val1 * steps);
	if (val->val2 != 0) {
		val->val2 *= 1000000;
		val->val2 /= steps;
	}

	return 0;
}

Fixes the error as now the value is a compile-time constant.

[Jørgen Holmefjord]

Hi,

I'm not able to reproduce this error. I tried adding QDEC to a simple example, but there are no build errors.

The QDEC is also used in our nrf_desktop mouse application, so it should have been tested and builds with our tests.

Can you upload a simple application that we can use to reproduce this error?

Best regards,
Jørgen

[ArchieA_C]

Hi Jørgen

It seems to be an issue when enabling CPLUSPLUS. Could you add `CONFIG_CPLUSPLUS=y` to your proj.conf in your test up and see if it errors? 

Edit: Actually it seems to be the `CONFIG_NO_OPTIMIZATIONS=y` option.

Also, how do I report an issue with the DevZone website? I have noticed that the "Reply", "Verify Answer" and "More" buttons do not appear next to posts unless I interact with those buttons on a post a level above the one I want to interact with. I can provide a video if that helps. 

Thanks,

Archie

[Jørgen Holmefjord]

Hi,

I was able to reproduce the issue with `CONFIG_NO_OPTIMIZATIONS=y` config set. I have reported it internally.

We do not have any other methods to report DevZone issues than creating a ticket. We are aware of the issues you have seen, F5 usually helps with showing the buttons.

Best regards,
Jørgen