"Undefined Reference" on the linker level

RE: "Undefined Reference" on the linker level

Connie Violet — Thu, 06 Dec 2018 03:45:35 GMT

OK. Turned out that when I combine our program with the example I had our version of sdk_config.h in the project directory but also the example's sdk_config.h in the config folder which cause the problem. It was solved by removing the config holder and also the related line in the Makefile.

RE: "Undefined Reference" on the linker level

Jørgen Holmefjord — Fri, 19 Oct 2018 14:37:04 GMT

I have reported both your concerns to our SDK team. We will see if we can get something better for future releases.

RE: "Undefined Reference" on the linker level

awneil — Fri, 19 Oct 2018 07:59:50 GMT

Absolutely!

That's exactly my point!

The module documentation does not clearly describe what settings need to be made.
The module documentation does not clearly state what files need to be added to the project.
Dependencies are poorly documented.

Another one this morning:

https://devzone.nordicsemi.com/f/nordic-q-a/39627/error-l6218e - relates to app_uart & nrfx_twim

So let's look at the UART documentation:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/group__app__uart.html?cp=4_0_0_6_11_57

Under 'UART driver configuration'

Again, we have APP_UART_ENABLED "Set to 1 to enable", but no clear definition of where to do that - just the cryptic "This is an NRF_CONFIG macro".

And I do not see anywhere that it tells you that files need to be added to the project - let alone what those files are!

This appears to be a classic case of documentation written by coder!

Jørgen Holmefjord - perhaps we could discuss doing an external review? PM me ...

RE: "Undefined Reference" on the linker level

Ladasky — Thu, 18 Oct 2018 23:53:03 GMT

http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v12.3.0%2Fsdk_config.html&cp=4_0_7_1_6 states:

"All examples contain a full configuration header file in which only the used modules are enabled." (emphasis mine)

With all due respect, this statement is untrue.

I just wrote a short program which simply counts the lines in each sdk_config.h file in SDK 12.3 which is designated for the PCA10040 board (the ones we use). Here is the output.

dtm/direct_test_mode/pca10040/blank/config/sdk_config.h: 135
dtm/direct_test_mode/pca10040/s332/config/sdk_config.h: 135
dtm/direct_test_mode/pca10040/s132/config/sdk_config.h: 135
dtm/dtm_serialization/pca10040/ser_s132_spi/config/sdk_config.h: 915
dtm/dtm_serialization/pca10040/ser_s132_uart/config/sdk_config.h: 746
dtm/dtm_serialization/pca10040/ser_s132_hci/config/sdk_config.h: 753
dtm/dtm_serialization/pca10040/ser_s132_spi_5W/config/sdk_config.h: 753
ble_peripheral/ble_app_beacon/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_keyboard/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_keyboard/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_keyboard/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_keyboard/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_bms/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hrs_freertos/pca10040/s132/config/sdk_config.h: 3811
ble_peripheral/ble_app_gls/pca10040/ser_s132_spi/config/sdk_config.h: 3804
ble_peripheral/ble_app_gls/pca10040/s132/config/sdk_config.h: 3804
ble_peripheral/ble_app_gls/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_gls/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/ble_app_cts_c/pca10040/ser_s132_spi/config/sdk_config.h: 3804
ble_peripheral/ble_app_cts_c/pca10040/s132/config/sdk_config.h: 3804
ble_peripheral/ble_app_cts_c/pca10040/ser_s132_uart/config/sdk_config.h: 3804
ble_peripheral/ble_app_cts_c/pca10040/ser_s132_hci/config/sdk_config.h: 3804
ble_peripheral/ble_app_cscs/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_cscs/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_cscs/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_cscs/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/ble_app_alert_notification/pca10040/ser_s132_spi/config/sdk_config.h: 3804
ble_peripheral/ble_app_alert_notification/pca10040/s132/config/sdk_config.h: 3804
ble_peripheral/ble_app_alert_notification/pca10040/ser_s132_uart/config/sdk_config.h: 3804
ble_peripheral/ble_app_alert_notification/pca10040/ser_s132_hci/config/sdk_config.h: 3804
ble_peripheral/ble_app_uart/pca10040/s132/config/sdk_config.h: 3811
ble_peripheral/ble_app_bps/pca10040/ser_s132_spi/config/sdk_config.h: 3804
ble_peripheral/ble_app_bps/pca10040/s132/config/sdk_config.h: 3804
ble_peripheral/ble_app_bps/pca10040/ser_s132_uart/config/sdk_config.h: 3804
ble_peripheral/ble_app_bps/pca10040/ser_s132_hci/config/sdk_config.h: 3804
ble_peripheral/ble_app_eddystone/pca10040/s132/config/sdk_config.h: 3804
ble_peripheral/ble_app_rscs/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_rscs/pca10040/s332/config/sdk_config.h: 3797
ble_peripheral/ble_app_rscs/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_rscs/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_rscs/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/ble_app_hrs/pca10040/ser_s132_spi/config/sdk_config.h: 3827
ble_peripheral/ble_app_hrs/pca10040/s332/config/sdk_config.h: 3827
ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h: 3837
ble_peripheral/ble_app_hrs/pca10040/ser_s132_uart/config/sdk_config.h: 3827
ble_peripheral/ble_app_hrs/pca10040/ser_s132_hci/config/sdk_config.h: 3827
ble_peripheral/ble_app_hrs/pca10040/ser_s132_spi_5W/config/sdk_config.h: 3827
ble_peripheral/experimental_ble_app_hids_keyboard_pairing_nfc/pca10040/s132/config/sdk_config.h: 3937
ble_peripheral/experimental_ble_app_buttonless_dfu/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_mouse/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_mouse/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_mouse/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_hids_mouse/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_hrs_pairing_nfc/pca10040/s132/config/sdk_config.h: 3951
ble_peripheral/experimental_ble_app_blinky/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_blinky/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_blinky/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_blinky/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/ble_app_proximity/pca10040/s132/config/sdk_config.h: 3811
ble_peripheral/experimental_ble_app_cgms/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hts/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_hts/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_hts/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_hts/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/ble_app_ancs_c/pca10040/ser_s132_spi/config/sdk_config.h: 3811
ble_peripheral/ble_app_ancs_c/pca10040/s132/config/sdk_config.h: 3811
ble_peripheral/ble_app_ancs_c/pca10040/ser_s132_uart/config/sdk_config.h: 3804
ble_peripheral/ble_app_ancs_c/pca10040/ser_s132_hci/config/sdk_config.h: 3804
ble_peripheral/ble_app_template/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_lns/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_lns/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_lns/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_lns/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_peripheral/experimental_bluetoothds_template/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/experimental_ble_app_queued_writes/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_pwr_profiling/pca10040/ser_s132_spi/config/sdk_config.h: 3797
ble_peripheral/ble_app_pwr_profiling/pca10040/s132/config/sdk_config.h: 3797
ble_peripheral/ble_app_pwr_profiling/pca10040/ser_s132_uart/config/sdk_config.h: 3797
ble_peripheral/ble_app_pwr_profiling/pca10040/ser_s132_hci/config/sdk_config.h: 3797
ble_central/ble_app_uart_c/pca10040/ser_s132_spi/config/sdk_config.h: 3818
ble_central/ble_app_uart_c/pca10040/s132/config/sdk_config.h: 3818
ble_central/ble_app_multilink_central/pca10040/s132/config/sdk_config.h: 3804
ble_central/experimental/ble_app_blinky_c/pca10040/s132/config/sdk_config.h: 3804
ble_central/experimental/ble_app_rscs_c/pca10040/ser_s132_spi/config/sdk_config.h: 3804
ble_central/experimental/ble_app_rscs_c/pca10040/s132/config/sdk_config.h: 3804
ble_central/ble_app_hrs_c/pca10040/ser_s132_spi/config/sdk_config.h: 3834
ble_central/ble_app_hrs_c/pca10040/s132/config/sdk_config.h: 3844
nfc/experimental_writable_ndef_msg/pca10040/blank/config/sdk_config.h: 754
nfc/wake_on_nfc/pca10040/blank/config/sdk_config.h: 699
nfc/record_text/pca10040/blank/config/sdk_config.h: 753
nfc/record_launch_app/pca10040/blank/config/sdk_config.h: 753
nfc/adafruit_tag_reader/pca10040/blank/config/sdk_config.h: 1250
nfc/record_url/pca10040/blank/config/sdk_config.h: 753
peripheral/rng/pca10040/blank/config/sdk_config.h: 3797
peripheral/rng/pca10040/s132/config/sdk_config.h: 3797
peripheral/uart/pca10040/blank/config/sdk_config.h: 516
peripheral/pwr_mgmt/pca10040/blank/config/sdk_config.h: 848
peripheral/csense_drv/pca10040/blank/config/sdk_config.h: 992
peripheral/blinky/pca10040/blank/config/sdk_config.h: 3797
peripheral/blinky/pca10040/s132/config/sdk_config.h: 3797
peripheral/temperature/pca10040/blank/config/sdk_config.h: 479
peripheral/rtc/pca10040/blank/config/sdk_config.h: 695
peripheral/preflash/pca10040/blank/config/sdk_config.h: 853
peripheral/wdt/pca10040/blank/config/sdk_config.h: 796
peripheral/csense/pca10040/blank/config/sdk_config.h: 1064
peripheral/twi_master_with_twis_slave/pca10040/blank/config/sdk_config.h: 909
peripheral/radio/transmitter/pca10040/blank/config/sdk_config.h: 633
peripheral/radio/receiver/pca10040/blank/config/sdk_config.h: 626
peripheral/uicr_config/pca10040/blank/config/sdk_config.h: 122
peripheral/saadc/pca10040/blank/config/sdk_config.h: 1007
peripheral/qdec/pca10040/blank/config/sdk_config.h: 721
peripheral/spi/pca10040/blank/config/sdk_config.h: 821
peripheral/pwm_library/pca10040/blank/config/sdk_config.h: 789
peripheral/blinky_systick/pca10040/blank/config/sdk_config.h: 135
peripheral/fpu_fft/pca10040/blank/config/sdk_config.h: 479
peripheral/fpu_fft/pca10040/s132/config/sdk_config.h: 608
peripheral/fpu_fft/pca10040/blank_irq/config/sdk_config.h: 479
peripheral/fpu_fft/pca10040/s132_irq/config/sdk_config.h: 608
peripheral/blinky_freertos/pca10040/blank/config/sdk_config.h: 699
peripheral/ppi/pca10040/blank/config/sdk_config.h: 692
peripheral/twi_master_using_app_twi/pca10040/blank/config/sdk_config.h: 960
peripheral/i2s/pca10040/blank/config/sdk_config.h: 700
peripheral/pwm_driver/pca10040/blank/config/sdk_config.h: 876
peripheral/gpiote/pca10040/blank/config/sdk_config.h: 776
peripheral/simple_timer/pca10040/blank/config/sdk_config.h: 791
peripheral/spis/pca10040/blank/config/sdk_config.h: 793
peripheral/twi_scanner/pca10040/blank/config/sdk_config.h: 614
peripheral/template_project/pca10040/blank/config/sdk_config.h: 3367
peripheral/radio_test/pca10040/blank/config/sdk_config.h: 516
peripheral/led_softblink/pca10040/blank/config/sdk_config.h: 622
peripheral/lpcomp/pca10040/blank/config/sdk_config.h: 614
peripheral/ram_retention/pca10040/blank/config/sdk_config.h: 122
peripheral/pin_change_int/pca10040/blank/config/sdk_config.h: 563
peripheral/twi_sensor/pca10040/blank/config/sdk_config.h: 614
peripheral/timer/pca10040/blank/config/sdk_config.h: 630
peripheral/flashwrite/pca10040/blank/config/sdk_config.h: 479
peripheral/low_power_pwm/pca10040/blank/config/sdk_config.h: 615
peripheral/bsp/pca10040/blank/config/sdk_config.h: 633
peripheral/fatfs/pca10040/blank/config/sdk_config.h: 718
ble_central_and_peripheral/experimental/ble_app_multirole_lesc/pca10040/s132/config/sdk_config.h: 3818
ble_central_and_peripheral/experimental/ble_app_hrs_rscs_relay/pca10040/s132/config/sdk_config.h: 3818
ble_central_and_peripheral/experimental/ble_app_att_mtu_throughput/pca10040/s132/config/sdk_config.h: 3884
ble_central_and_peripheral/ble_connectivity/pca10040/ser_s132_spi/config/sdk_config.h: 862
ble_central_and_peripheral/ble_connectivity/pca10040/ser_s132_uart/config/sdk_config.h: 661
ble_central_and_peripheral/ble_connectivity/pca10040/ser_s132_hci/config/sdk_config.h: 675
ble_central_and_peripheral/ble_connectivity/pca10040/ser_s132_spi_5W/config/sdk_config.h: 862
multiprotocol/experimental_ble_app_gzll/pca10040/s132/config/sdk_config.h: 3811
multiprotocol/ble_ant_app_hrm/pca10040/s332/config/sdk_config.h: 1155
proprietary_rf/esb_ptx/pca10040/blank/config/sdk_config.h: 479
proprietary_rf/esb_prx/pca10040/blank/config/sdk_config.h: 479
proprietary_rf/gzll/experimental/gzp_dynamic_pairing/device/pca10040/blank/config/sdk_config.h: 602
proprietary_rf/gzll/experimental/gzp_dynamic_pairing/host/pca10040/blank/config/sdk_config.h: 602
proprietary_rf/gzll/experimental/gzll_ack_payload/device/pca10040/blank/config/sdk_config.h: 602
proprietary_rf/gzll/experimental/gzll_ack_payload/host/pca10040/blank/config/sdk_config.h: 602
proprietary_rf/gzll/experimental/gzp_desktop_emulator/pca10040/config/sdk_config.h: 516
proprietary_rf/esb_low_power_ptx/pca10040/blank/config/sdk_config.h: 479
proprietary_rf/esb_low_power_prx/pca10040/blank/config/sdk_config.h: 479
dfu/bootloader_secure/pca10040/config/sdk_config.h: 515
dfu/bootloader_secure/pca10040_debug/config/sdk_config.h: 654
dfu/experimental_ant_bootloader/pca10040/dual_bank_ant_s332/config/sdk_config.h: 868
dfu/experimental_ant_bootloader/pca10040/dual_bank_ant_s212/config/sdk_config.h: 868
dfu/experimental_ant_bootloader/ota_tester/pca10040/s332/config/sdk_config.h: 527
dfu/experimental_ant_bootloader/ota_tester/pca10040/s212/config/sdk_config.h: 527
ant/ant_time_synchronization/tx/pca10040/s212/config/sdk_config.h: 786
ant/ant_time_synchronization/rx/pca10040/s212/config/sdk_config.h: 809
ant/ant_search_sharing/pca10040/s212/config/sdk_config.h: 839
ant/ant_broadcast/tx/pca10040/s212/config/sdk_config.h: 786
ant/ant_broadcast/rx/pca10040/s212/config/sdk_config.h: 786
ant/ant_cw_mode/pca10040/s212/config/sdk_config.h: 640
ant/ant_continuous_scanning_controller/pca10040/s212/config/sdk_config.h: 797
ant/ant_high_duty_search_and_background_scanning/pca10040/s212/config/sdk_config.h: 797
ant/ant_multi_channels/tx/pca10040/s212/config/sdk_config.h: 774
ant/ant_multi_channels/rx/pca10040/s212/config/sdk_config.h: 797
ant/ant_debug/pca10040/s212/config/sdk_config.h: 826
ant/ant_background_scanning/pca10040/s212/config/sdk_config.h: 797
ant/ant_plus/ant_hrm/hrm_tx/pca10040/s212/config/sdk_config.h: 1072
ant/ant_plus/ant_hrm/hrm_rx/pca10040/s212/config/sdk_config.h: 993
ant/ant_plus/ant_sdm/sdm_tx/pca10040/s212/config/sdk_config.h: 1238
ant/ant_plus/ant_sdm/sdm_rx/pca10040/s212/config/sdk_config.h: 1138
ant/ant_plus/ant_bpwr/bpwr_rx/pca10040/s212/config/sdk_config.h: 1122
ant/ant_plus/ant_bpwr/bpwr_tx/pca10040/s212/config/sdk_config.h: 1201
ant/ant_plus/ant_bsc/bsc_tx/pca10040/s212/config/sdk_config.h: 1135
ant/ant_plus/ant_bsc/bsc_rx/pca10040/s212/config/sdk_config.h: 1083
ant/experimental/ant_shared_channel/slave/pca10040/s212/config/sdk_config.h: 644
ant/experimental/ant_shared_channel/master_to_master/pca10040/s332/config/sdk_config.h: 741
ant/ant_relay_demo/pca10040/s212/config/sdk_config.h: 835
ant/ant_message_types/master/pca10040/s332/config/sdk_config.h: 774
ant/ant_message_types/master/pca10040/s212/config/sdk_config.h: 774
ant/ant_async_transmitter/pca10040/s212/config/sdk_config.h: 797
ant/ant_fs/client/pca10040/s212/config/sdk_config.h: 926
ant/ant_io_demo/ant_io_rx/pca10040/s212/config/sdk_config.h: 802
ant/ant_io_demo/ant_io_tx/pca10040/s212/config/sdk_config.h: 797
ant/ant_scan_and_forward/pca10040/s212/config/sdk_config.h: 802
ant/ant_search_uplink/pca10040/s212/config/sdk_config.h: 792
ant/ant_multi_channels_encrypted/tx/pca10040/s212/config/sdk_config.h: 781
ant/ant_multi_channels_encrypted/rx/pca10040/s212/config/sdk_config.h: 811
ant/ant_advanced_burst/pca10040/s212/config/sdk_config.h: 781

These files differ by A LOT. It's not just which flags are 1 and which flags are 0. Hundreds, even thousands of lines may differ. Some flags are only defined in certain sdk_config.h files. I have found it challenging to identify the differences between sdk_config.h files, and to merge them when I need multiple subsystems to work together.

RE: "Undefined Reference" on the linker level

Connie Violet — Thu, 18 Oct 2018 02:12:08 GMT

Hi, Jorgen. I did checked and made sure that this part in my sdk_config.h look the same as what you pasted here but it did not solve the problem, and that was why I made this post.

RE: "Undefined Reference" on the linker level

awneil — Wed, 17 Oct 2018 16:35:39 GMT

That's good to hear!

So, for input to that task, let's just look at the TWI driver as an example:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/group__nrfx__twi.html

I don't see anything there at all which tells which files need to be added to a Project.

There is a link to "TWI peripheral driver configuration"

This does list NRFX_TWI_ENABLED - and says "set to 1 to activate"

But it's not really clear where that setting has to be made.

There's a note saying, "This is an NRF_CONFIG macro" - but what does that mean?

I guess it's supposed to tell us that it's in sdk_config.h - is it?

It would be clearer if that were explicitly stated - with a link to the sdk_config.h documentation.

RE: "Undefined Reference" on the linker level

Jørgen Holmefjord — Wed, 17 Oct 2018 12:39:29 GMT

Like I said, I agree that this is not well documented. We have an internal task requesting more documentation on library dependency documentation.

RE: "Undefined Reference" on the linker level

awneil — Wed, 17 Oct 2018 12:11:41 GMT

[quote userid="14926" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/153211"]this is more related to the modules themselves, rather than the sdk_config.h file[/quote]

Indeed.

But see my linked thread - I didn't see anywhere that told me what files I needed to include!

[quote userid="14926" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/153211"]the compiler will give you hints to what needs to be included/enabled[/quote]

Indeed - but we're back to development by reverse-engineering again.

We shouldn't have to discover this stuff by trial & error - it should be clearly documented up-front.

RE: "Undefined Reference" on the linker level

Jørgen Holmefjord — Wed, 17 Oct 2018 11:39:43 GMT

I agree that dependencies could have been documented better, but this is more related to the modules themselves, rather than the sdk_config.h file. You still needs to include the source files of the dependent modules.

It might take some iterations to add all sub-modules that a module depends on, but the compiler will give you hints to what needs to be included/enabled.

RE: "Undefined Reference" on the linker level

awneil — Tue, 16 Oct 2018 09:35:39 GMT

and why does the forum quote feature keep going wrong like that - ie, the quoted text is outside the quote marker!

RE: "Undefined Reference" on the linker level

awneil — Tue, 16 Oct 2018 09:34:18 GMT

[quote userid="14926" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/153008"][/quote]

I think it is explained well in the documentation:

"Every module in SDK contains at least one configuration option that enables this module

I didn't find that it was always easy to identify what configuration option(s) is/are required by a particular module.

Especially as some (many? most?) modules have dependencies on other modules.

Plus the added confusion of there often being NRFX and "legacy" versions of the same thing ...

eg, see: https://devzone.nordicsemi.com/f/nordic-q-a/39469/linking-mpu6050-sensor-with-ble-uart/152957#152957

RE: "Undefined Reference" on the linker level

Jørgen Holmefjord — Tue, 16 Oct 2018 09:23:40 GMT

[quote userid="6462" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/153004"]However, in this case, I would have thought you would have got compile errors?[/quote]

As long as the header file where the function is declared is included, you will not get compilation error. If header file is included but source file is not included in project, you will get this linker error.

[quote userid="6462" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/153004"]this one is a frequent cause of confusion - so maybe there's a clue for Nordic there, that it needs to be better explained...?[/quote]

I think it is explained well in the documentation:

"Every module in SDK contains at least one configuration option that enables this module. If the module is disabled, then even if source code is added to the project, it is not compiled because the module implementation is conditionally included."

I will say that is should be expected of customers to read through the Getting Started section of the SDK documentation to get familiar with the SDK before starting to develop applications.

RE: "Undefined Reference" on the linker level

awneil — Tue, 16 Oct 2018 09:12:42 GMT

[quote userid="14926" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/152988"]You have not included the source file that implements the functions in your project[/quote]

This is a standard 'C' issue - nothing specifically to do with Nordic.

However, in this case, I would have thought you would have got compile errors?

[quote userid="14926" url="~/f/nordic-q-a/39503/undefined-reference-on-the-linker-level/152988"]ou have not enabled the module in your project's sdk_config.h file.[/quote]

This one is specific to the way Nordic configure their SDKs.

As Jørgen Holmefjord said, this one is a frequent cause of confusion - so maybe there's a clue for Nordic there, that it needs to be better explained...?

RE: "Undefined Reference" on the linker level

Jørgen Holmefjord — Tue, 16 Oct 2018 08:34:44 GMT

Hi,

This is caused by one of (or both) the following things:

You have not included the source file that implements the functions in your project. In SDK 12.3.0, these functions are implemented in the source file 'nRF5_SDK_12.3.0_d7731ad\components\drivers_nrf\twi_master\nrf_drv_twi.c'
You have not enabled the module in your project's sdk_config.h file. Check if you can find TWI_ENABLED in the file, and set it to 1. If you cannot find this section in the sdk_config.h file in the BLE project, you need to copy the entire section related to the TWI master driver from one of the TWI master projects and add it to the sdk_config.h file of your BLE project.

// <e> TWI_ENABLED - nrf_drv_twi - TWI/TWIM peripheral driver
//==========================================================
#ifndef TWI_ENABLED
#define TWI_ENABLED 1
#endif
#if  TWI_ENABLED
// <o> TWI_DEFAULT_CONFIG_FREQUENCY  - Frequency
 
// <26738688=> 100k 
// <67108864=> 250k 
// <104857600=> 400k 

#ifndef TWI_DEFAULT_CONFIG_FREQUENCY
#define TWI_DEFAULT_CONFIG_FREQUENCY 26738688
#endif

// <q> TWI_DEFAULT_CONFIG_CLR_BUS_INIT  - Enables bus clearing procedure during init
 

#ifndef TWI_DEFAULT_CONFIG_CLR_BUS_INIT
#define TWI_DEFAULT_CONFIG_CLR_BUS_INIT 0
#endif

// <q> TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT  - Enables bus holding after uninit
 

#ifndef TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT
#define TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT 0
#endif

// <o> TWI_DEFAULT_CONFIG_IRQ_PRIORITY  - Interrupt priority
 

// <i> Priorities 0,2 (nRF51) and 0,1,4,5 (nRF52) are reserved for SoftDevice
// <0=> 0 (highest) 
// <1=> 1 
// <2=> 2 
// <3=> 3 
// <4=> 4 
// <5=> 5 
// <6=> 6 
// <7=> 7 

#ifndef TWI_DEFAULT_CONFIG_IRQ_PRIORITY
#define TWI_DEFAULT_CONFIG_IRQ_PRIORITY 7
#endif

// <e> TWI0_ENABLED - Enable TWI0 instance
//==========================================================
#ifndef TWI0_ENABLED
#define TWI0_ENABLED 1
#endif
#if  TWI0_ENABLED
// <q> TWI0_USE_EASY_DMA  - Use EasyDMA (if present)
 

#ifndef TWI0_USE_EASY_DMA
#define TWI0_USE_EASY_DMA 1
#endif

#endif //TWI0_ENABLED
// </e>

// <e> TWI1_ENABLED - Enable TWI1 instance
//==========================================================
#ifndef TWI1_ENABLED
#define TWI1_ENABLED 0
#endif
#if  TWI1_ENABLED
// <q> TWI1_USE_EASY_DMA  - Use EasyDMA (if present)
 

#ifndef TWI1_USE_EASY_DMA
#define TWI1_USE_EASY_DMA 0
#endif

#endif //TWI1_ENABLED
// </e>

// <e> TWI_CONFIG_LOG_ENABLED - Enables logging in the module.
//==========================================================
#ifndef TWI_CONFIG_LOG_ENABLED
#define TWI_CONFIG_LOG_ENABLED 0
#endif
#if  TWI_CONFIG_LOG_ENABLED
// <o> TWI_CONFIG_LOG_LEVEL  - Default Severity level
 
// <0=> Off 
// <1=> Error 
// <2=> Warning 
// <3=> Info 
// <4=> Debug 

#ifndef TWI_CONFIG_LOG_LEVEL
#define TWI_CONFIG_LOG_LEVEL 3
#endif

// <o> TWI_CONFIG_INFO_COLOR  - ANSI escape code prefix.
 
// <0=> Default 
// <1=> Black 
// <2=> Red 
// <3=> Green 
// <4=> Yellow 
// <5=> Blue 
// <6=> Magenta 
// <7=> Cyan 
// <8=> White 

#ifndef TWI_CONFIG_INFO_COLOR
#define TWI_CONFIG_INFO_COLOR 0
#endif

// <o> TWI_CONFIG_DEBUG_COLOR  - ANSI escape code prefix.
 
// <0=> Default 
// <1=> Black 
// <2=> Red 
// <3=> Green 
// <4=> Yellow 
// <5=> Blue 
// <6=> Magenta 
// <7=> Cyan 
// <8=> White 

#ifndef TWI_CONFIG_DEBUG_COLOR
#define TWI_CONFIG_DEBUG_COLOR 0
#endif

#endif //TWI_CONFIG_LOG_ENABLED
// </e>

#endif //TWI_ENABLED
// </e>

If you had spent 1 minute searching DevZone for the errors you are experiencing, you would have found countless other questions answering how to solve this issue.

Best regards,
Jørgen