Hard Fault using TWI_SCANNER example

Question

Hello, 
 Trying to run the TWI_SCANNER example on a pca10100 hard faults. The .emProject file has been modified per the instructions at https://devzone.nordicsemi.com/f/nordic-q-a/57816/ble_app_beacon-not-available-for-pca10100/234466#234466 
 The fault is consistently at this location: 
 The registers are as follows at this point in the code: 
 
 Code is as follows: 
 #include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"



#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

/* TWI instance ID. */
#if TWI0_ENABLED
#define TWI_INSTANCE_ID 0
#elif TWI1_ENABLED
#define TWI_INSTANCE_ID 1
#endif

 /* Number of possible TWI addresses. */
 #define TWI_ADDRESSES 127

/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);


/**
 * @brief TWI initialization.
 */
void twi_init (void)
{
 ret_code_t err_code;

 const nrf_drv_twi_config_t twi_config = {
 .scl = 26,
 .sda = 27,
 .frequency = NRF_DRV_TWI_FREQ_100K,
 .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
 .clear_bus_init = false
 };

 err_code = nrf_drv_twi_init(&m_twi, &twi_config, app_error_handler_bare, NULL);
 APP_ERROR_CHECK(err_code);

 nrf_drv_twi_enable(&m_twi);
}


/**
 * @brief Function for main application entry.
 */
int main(void)
{
 ret_code_t err_code;
 uint8_t address;
 uint8_t sample_data;
 bool detected_device = false;

 APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
 NRF_LOG_DEFAULT_BACKENDS_INIT();

 NRF_LOG_INFO("TWI scanner started.");
 NRF_LOG_FLUSH();
 twi_init();

 for (address = 1; address <= TWI_ADDRESSES; address++)
 {
 err_code = nrf_drv_twi_rx(&m_twi, address, &sample_data, sizeof(sample_data));
 if (err_code == NRF_SUCCESS)
 {
 detected_device = true;
 NRF_LOG_INFO("TWI device detected at address 0x%x.", address);
 }
 NRF_LOG_FLUSH();
 }

 if (!detected_device)
 {
 NRF_LOG_INFO("No device was found.");
 NRF_LOG_FLUSH();
 }

 //while (true)
 //{
 // NRF_LOG_INFO("No device was found.");
 //}
} 
 
 However, even removing all of the code (i.e. leaving void main(void){} completely empty except for an empty while loop) results in the exact same hard fault. I get no build errors, and the code deploys without error or fault via J-Link. 
 
 Would appreciate some guidance. 
 Best, S.

Håkon Alseth · Accepted Answer

Hi, 
 
 scath said: However, I now detect a valid TWI device at 0x00 - 
 you should start scanning from address=1. 
 scath said: To clarify the language "This happens when I switch pins", what I mean is I get the same address (0x00) even when I manually change the SCL and SDA pins to address two different devices. Example: Device 1) SCL:P0.21, SDA:P0.20 - in this instance I expect an address between 0x2a or 0x2b Device 2) SCL:P0.26, SDA:P0.27 - in this instance I expect one of six addresses, none of them are 0x00 
 Have you scoped the lines to see what happens? 
 scath said: The issue was in trying to use the pca10056 solution; I got no hard faults when I switch to the 10040 solution and run the same code. 
 Did you remove the pca10056 system files and add system_nrf52833 and nrf52833-startup files? 
 scath said: Lastly, I'm relying on the nrf52833's internal pullups to set the signals high. It looks like this is happening by default - can you confirm? 
 Yes, nrfx_twim.c enables pull-ups in the pad. 
 
 Kind regards, 
 Håkon

Hard Fault using TWI_SCANNER example

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