SHT4x interface with nRF52840

[kaushalyasat]

Hi,

I am trying to integrate Sensirion SHT40 sensor with nRF52840. I am using the sensor sample app from 2.9.0 SDK. I am building with 2.6.1 SDK with toolchain 2.6.1.  The build is ok, but when the app starts, it just get stuck as I can see in the console as follows.

[00:00:00.003,143] <inf> ieee802154_nrf5: nRF5 802154 radio initialized
[00:00:00.003,173] <dbg> temp_nrf5_mpsl: temp_nrf5_mpsl_init:
[00:00:00.009,490] <inf> fs_nvs: 8 Sectors of 4096 bytes
[00:00:00.

Then I added CONFIG_COAP_CLIENT=y to prj.conf and I get the following.

[00:00:00.[00:00[00:00:00.003,326] <dbg> temp_nrf5_mpsl: temp_nrf5_mpsl_init:
[00:00:00.009,643] <inf> fs_nvs: 8 Sectors of 4096 bytes
[00:00:00.009,643] <inf> fs_nvs: alloc wra: 0, e00
[00:00:00.009,674] <inf> fs_nvs: data wra: 0, 810
*** Booting nRF Connect SDK v3.5.99-ncs1-1 ***
ASSERTION FAIL @ WEST_TOPDIR/zephyr/kernel/thread.c:601
        invalid priority (15); allowed range: 14 to -16
[00:00:00.038,909] <dbg> temp_nrf5_mpsl: temp_nrf5_mpsl_sample_fetch: sample: 96
[00:00:00.038,940] <dbg> temp_nrf5_mpsl: temp_nrf5_mpsl_channel_get: Temperature:24,0
[00:00:00.039,031] <err> os: r0/a1:  0x00000004  r1/a2:  0x00000259  r2/a3:  0x00000009
[00:00:00.039,062] <err> os: r3/a4:  0x20001a40 r12/ip:  0x00000014 r14/lr:  0x00022321
[00:00:00.039,062] <err> os:  xpsr:  0x41000000
[00:00:00.039,093] <err> os: s[ 0]:  0x00000001  s[ 1]:  0x20003f10  s[ 2]:  0x20002bf8  s[ 3]:  0x0003b379
[00:00:00.039,093] <err> os: s[ 4]:  0x00000000  s[ 5]:  0x00000000  s[ 6]:  0x000539d0  s[ 7]:  0x20015744
[00:00:00.039,123] <err> os: s[ 8]:  0x20002bf8  s[ 9]:  0x0003ac5d  s[10]:  0x000539d0  s[11]:  0x20015744
[00:00:00.039,154] <err> os: s[12]:  0x0000000e  s[13]:  0x00022317  s[14]:  0x000539d0  s[15]:  0x0000000f
[00:00:00.039,154] <err> os: fpscr:  0x0000000e
[00:00:00.039,154] <err> os: Faulting instruction address (r15/pc): 0x0003ac4a
[00:00:00.039,215] <err> os: >>> ZEPHYR FATAL ERROR 4: Kernel panic on CPU 0
[00:00:00.039,245] <err> os: Current thread: 0x20003f10 (main)

I have attached my prj.conf and overlay file.

87304.prj.conf

6366.nrf52840dk_nrf52840.overlay

I haven't modified any thread priority. I tried searching for where this priorities are assigned, but couldn't find that either.

Please help.

Cheers,

Kaushalya

[kaushalyasat]

Hi, I think with 

CONFIG_COAP_CLIENT=n

I can go ahead. What I saw as program getting stuck in the first occurrence, is not actually a stuck, just the console getting disabled to preserve battery power. 

But I am still curious to know what does the  'CONFIG_COAP_CLIENT' do and why the issue with thread priority.

Cheers,

Kaushalya

[Vidar Berg]

Hello Kaushalya,

The log shows you are reading the temperature from the nRF52's TEMP peripheral, not the external sht40 sensor. Maybe you selected the wrong sensor device in your app?

Regarding the assertion, it appears to be raised for the main thread if I'm the crash log correctly, but I don't see why this would happen when enabling the CONFIG_COAP_CLIENT symbol. Please check the generated configuration file (.config) for your application located in the build directory and check if the CONFIG_MAIN_THREAD_PRIORITY is set to '0' in both cases.

Cheers,

Vidar

[kaushalyasat]

Hi Vidar,

Many thanks for lookin into this. 

Thats interesting observation that I am using Temp peripheral. How do we enable Temp peripheral? 

What I have done in my case is

1. Enable Sensirion SHT4x node under I2C node in the device tree as follows. 

 

&pinctrl {
	i2c0_default: i2c0_default {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 1, 15)>,
				<NRF_PSEL(TWIM_SCL, 1, 13)>;
		};
	};

	i2c0_sleep: i2c0_sleep {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 1, 15)>,
				<NRF_PSEL(TWIM_SCL, 1, 13)>;
			low-power-enable;
		};
	};
};

&i2c0 {
	status = "okay";
	clock-frequency = <I2C_BITRATE_FAST>;
	sht4x@44 {
		status = "okay";
		compatible = "sensirion,sht4x";
		reg = <0x44>;
		repeatability = <2>;
	};
};

2. Access it from coap_client.c as follows.

const struct device *const sht = DEVICE_DT_GET_ANY(sensirion_sht4x);
struct sensor_value temp, hum;

#if !DT_HAS_COMPAT_STATUS_OKAY(sensirion_sht4x)		// Feature 17
#error "No sensirion,sgp40 compatible node found in the device tree"
#endif
.
.
void ADCscan () {
	if (sensor_sample_fetch(sht)) {
		LOG_INF("Failed to fetch sample from SHT4X device\n");
		return;
	}
	sensor_channel_get(sht, SENSOR_CHAN_AMBIENT_TEMP, &temp);
	sensor_channel_get(sht, SENSOR_CHAN_HUMIDITY, &hum);

	LOG_INF("SHT4X: %.2f Temp. [C] ; %0.2f RH [%%]",
		sensor_value_to_float(&temp),
		sensor_value_to_float(&hum));
 
    .
    .
}

int main () {
	if (!device_is_ready(sht)) {
		LOG_INF("Device %s is not ready.\n", sht->name);
		return 0;
	}
	ADCscan ();
	.
	.
}

Is there anything you see I have not done correctly here for getting data from SHT40? I get both temperature and humidity readings in my case and both values seems to change with environmental conditions. Furthermore I can see the I2C signals on bus as well. So seems like the data is originating from the SGT40 sensor.

Vidar Berg said:

 CONFIG_MAIN_THREAD_PRIORITY is set to '0' in both cases.

I checked that in both cases of CONFIG_COAP_CLIENT, the CONFIG_MAIN_THREAD_PRIORITY  is 0, but when CONFIG_COAP_CLIENT is enabled it crashes as before.

This is my .config file.

5734..config.zip

[kaushalyasat]

I can see "CONFIG_TEMP_NRF5_MPSL=y" in the .config file, which indicates use of internal temp sensor. When I do Menuconfig, I can see TEMP_NRF5_MPSL is enabled under Device Drivers, but its readonly. 

[Vidar Berg]

Sorry, the last code snippet shows that you are correctly fetching data from your sht40 sensor. I just saw references to the  "temp_nrf5_mpsl" driver in the log you posted and assumed you may have selected the SoC's built-in temperature sensor like in the CPU die temperature polling sample. This internal temperature sensor is used by the clock calibration and the 15.4 radio driver and that is why it is enabled in your project.

Regarding the assertion, the problem appears to be that CONFIG_COAP_CLIENT_THREAD_PRIORITY defaults to CONFIG_NUM_PREEMPT_PRIORITIES instead of CONFIG_NUM_PREEMPT_PRIORITIES - 1.

https://github.com/zephyrproject-rtos/zephyr/blob/2eb8cfb7f5084d040725dc0f4c61b526fa40b8f0/subsys/net/lib/coap/Kconfig#L114 

I will report this as a bug internally. The fix for now is to assign an appropriate priority level for the coap thread in your prj.conf file. For example: CONFIG_COAP_CLIENT_THREAD_PRIORITY=0.