nRF52840 module and SHT21 sensor

RE: nRF52840 module and SHT21 sensor

Hannu Hirvonen — Tue, 19 Mar 2019 12:06:35 GMT

Hello,

Case solved. twi_scanner can't "scan" SHT21 sensor, but when reading and writing directly using address 0x40 sensor works fine. No I at least know quite well how TWI works and big thanks for PicoScope 🙂

-Hannu-

RE: nRF52840 module and SHT21 sensor

Hannu Hirvonen — Wed, 13 Mar 2019 12:07:40 GMT

You didn't understood my question correctly. I know that there is a RTCC chip in Laird DVK BL654, but because I don't use them SmartBasic but your SoftDevice they can't help (and don't help) because it is your stuff.

Yes I know how I2C/TWI works.

I'm familiar with SW development since 1988, when you started ? With microcontrollers started 1993, when you ?

I have heard something that return codes does help sometimes :)

-Hannu-

RE: nRF52840 module and SHT21 sensor

awneil — Wed, 13 Mar 2019 10:21:03 GMT

You've missed the point!

You need to ask Laird for answers to specific questions about their products - like whether their module has an RTC chip, and how it is connected, etc. Nordic cannot help you with that.

Nordic can help you with things that are not specific to Laird - like how to use the nRF52840's TWI peripheral.

[quote userid="67122" url="~/f/nordic-q-a/44433/nrf52840-module-and-sht21-sensor/175825"]It should help much when investigating how does this I2C/TWI work in practice[/quote]

Do you understand the basics of how I2C works?

It is an industry standard - not specific to Nordic.

Start here:

https://www.nxp.com/docs/en/user-guide/UM10204.pdf - I2C Specification

https://en.wikipedia.org/wiki/I%C2%B2C

Are you familiar with software development in general, and embedded microcontrollers in particular?

When an API function returns an error code, that code will give you information about what's gone wrong - so it is important that you look-up the documentation of the error code.

So, again, have you looked up the meaning of the NRF_ERROR_DRV_TWI_ERR_ANACK error code?

You can use your IDE's search/browse facilities to find it.

Or just put "NRF_ERROR_DRV_TWI_ERR_ANACK" into google:

https://devzone.nordicsemi.com/f/nordic-q-a/21891/nrf_error_drv_twi_err_anack-in-blocking-mode

https://arduino.stackexchange.com/questions/21850/what-does-it-mean-in-i2c-nack-received

RE: nRF52840 module and SHT21 sensor

Hannu Hirvonen — Wed, 13 Mar 2019 07:55:17 GMT

Hello,

I'm currently investigating with Laird DVK BL654 how to use I2C/TWI, but this twi_scanner didn't there either. If I ask help from Laird they say that ask from Nordic because I use Nordic SD (not SmartBasic) and if ask help from Nordic you say that ask from Laird because I'm using their DVK. I'm quite sure that this twi_scanner example program did't work correctly. Is it so that their is not I2C sensor in nRF52840 evaluation board ? It should help much when investigating how does this I2C/TWI work in practice.

-Hannu-

RE: nRF52840 module and SHT21 sensor

awneil — Tue, 12 Mar 2019 17:48:07 GMT

[quote userid="67122" url="~/f/nordic-q-a/44433/nrf52840-module-and-sht21-sensor/175762"]When I can't see it I get error 0x00008201 = NRF_ERROR_DRV_TWI_ERR_ANACK[/quote]

So have you looked-up what that error means?

Again, have you looked at what's happening on the I2C lines with an oscilloscope?

RE: nRF52840 module and SHT21 sensor

Hannu Hirvonen — Tue, 12 Mar 2019 17:06:23 GMT

Hello,

Sometimes I can see SHT21 chip on I2C/TWI bus, but typically not ? When I can't see it I get error 0x00008201 = NRF_ERROR_DRV_TWI_ERR_ANACK. Just using twi_scanner example code. Any ideas how to get it working and is there someone who is familiar with this SHT21 chip ?

-Hannu-

RE: nRF52840 module and SHT21 sensor

awneil — Thu, 07 Mar 2019 12:19:36 GMT

[quote userid="67122" url="~/f/nordic-q-a/44433/nrf52840-module-and-sht21-sensor/174784"] I'm not sure if problem is in SD or driver or where ?[/quote]

Well, as you said in the OP, you could easily eliminate the SD by simply using a project which doesn't have the SD.

Other than that, are you checking for error reports in the code?

Have you looked at what's happening on the I2C lines with an oscilloscope?

RE: nRF52840 module and SHT21 sensor

Hannu Hirvonen — Thu, 07 Mar 2019 11:06:51 GMT

Hello Sigurd,

Problem is that using twi_scanner project I can see device 0x40 = 100 0000 now and then. I'm not sure if problem is in SD or driver or where ? Sometimes it works fine, but sometimes doesn't. Are you familiar with this SHT21 temperature/humidity sensor using I2C / TWI ?

-Hannu-

RE: nRF52840 module and SHT21 sensor

Sigurd — Thu, 07 Mar 2019 10:29:13 GMT

Hi,

A test program that verifies that the temperature and humidity are within valid ranges sounds like a good idea. An extended test could be to run the test program over time, logging the temperature, and see if it stays within the expected temperature range.