Persistent Failure in ble_stack_init() with sd_softdevice_enable (Error 8194) on nRF52840 (PCA10056, S140)

Hello Nordic community,

I’m working on a project with the nRF52840 DK (PCA10056) using the nRF5 SDK and the S140 SoftDevice.

My goal is to:

1. Read two NTC thermistors using SAADC (P0.30/AIN6 and P0.31/AIN7) every 100 ms.
2. Control an NTC enable pin (NTC_EN) on P0.29 to power the NTC circuit.
3. Toggle an LED (P0.24) every 200 ms.
4. Set a reset pin (P0.13) high after 10 seconds and stop NTC sampling.
5. Advertise via BLE


Issue:

The ble_stack_init() function consistently fails at sd_softdevice_enable(), returning error code 8194 (0x2002). I’ve confirmed the SoftDevice is flashed.

Here’s the relevant log:

<info> app: NTC SAADC with LED and Reset Control
<error> app: SoftDevice enable failed: 8194 

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#include <stdint.h>
#include "nrf.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "nrf_drv_saadc.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "ble.h"
#include "ble_advdata.h"
#include "ble_conn_params.h"
#include "app_timer.h"
#include "app_error.h"
// Pin definitions (nRF52840)
#define LED_PIN 24 // P0.24 for LED
#define SR_RESET_PIN 13 // P0.13 for reset (pin 33)
#define NTC_EN 29 // P0.20 for NTC enable
#define NTC1_AIN NRF_SAADC_INPUT_AIN6 // P0.30 (pin 10)
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