Nordic SDK printing to serial - c

Question

I have an Arduino device that runs on the Nordic SDK (it's a Red Bear Lab BLE nano). I want to be able to do a serial print into GTKTerm to be able to debug what is going on in my code. To do this I have the following code:
/*
* Copyright (c) 2014 Nordic Semiconductor. All Rights Reserved.
*
* The information contained herein is confidential property of Nordic Semiconductor. The use,
* copying, transfer or disclosure of such information is prohibited except by express written
* agreement with Nordic Semiconductor.
*
*/
/**
* #brief BLE Heart Rate Collector application main file.
*
* This file contains the source code for a sample heart rate collector.
*/
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf_sdm.h"
#include "ble.h"
#include "ble_hci.h"
#include "ble_db_discovery.h"
#include "softdevice_handler.h"
#include "app_util.h"
#include "app_error.h"
#include "boards.h"
#include "nrf_gpio.h"
#include "pstorage.h"
#include "device_manager.h"
#include "app_trace.h"
#include "ble_hrs_c.h"
#include "ble_bas_c.h"
#include "app_util.h"
#include "app_timer.h"
#include "bsp.h"
#include "bsp_btn_ble.h"
#define UART_TX_BUF_SIZE 256 /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE 1 /**< UART RX buffer size. */
#define STRING_BUFFER_LEN 50
#define BOND_DELETE_ALL_BUTTON_ID 0 /**< Button used for deleting all bonded centrals during startup. */
#define APP_TIMER_PRESCALER 0 /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_MAX_TIMERS (2+BSP_APP_TIMERS_NUMBER) /**< Maximum number of simultaneously created timers. */
#define APP_TIMER_OP_QUEUE_SIZE 2 /**< Size of timer operation queues. */
#define APPL_LOG app_trace_log /**< Debug logger macro that will be used in this file to do logging of debug information over UART. */
#define SEC_PARAM_BOND 1 /**< Perform bonding. */
#define SEC_PARAM_MITM 1 /**< Man In The Middle protection not required. */
#define SEC_PARAM_IO_CAPABILITIES BLE_GAP_IO_CAPS_NONE /**< No I/O capabilities. */
#define SEC_PARAM_OOB 0 /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE 7 /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE 16 /**< Maximum encryption key size. */
#define SCAN_INTERVAL 0x00A0 /**< Determines scan interval in units of 0.625 millisecond. */
#define SCAN_WINDOW 0x0050 /**< Determines scan window in units of 0.625 millisecond. */
#define MIN_CONNECTION_INTERVAL MSEC_TO_UNITS(7.5, UNIT_1_25_MS) /**< Determines minimum connection interval in millisecond. */
#define MAX_CONNECTION_INTERVAL MSEC_TO_UNITS(30, UNIT_1_25_MS) /**< Determines maximum connection interval in millisecond. */
#define SLAVE_LATENCY 0 /**< Determines slave latency in counts of connection events. */
#define SUPERVISION_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Determines supervision time-out in units of 10 millisecond. */
#define TARGET_UUID 0x180D /**< Target device name that application is looking for. */
#define MAX_PEER_COUNT DEVICE_MANAGER_MAX_CONNECTIONS /**< Maximum number of peer's application intends to manage. */
#define UUID16_SIZE 2 /**< Size of 16 bit UUID */
/**#breif Macro to unpack 16bit unsigned UUID from octet stream. */
#define UUID16_EXTRACT(DST, SRC) \
do \
{ \
(*(DST)) = (SRC)[1]; \
(*(DST)) <<= 8; \
(*(DST)) |= (SRC)[0]; \
} while (0)
/**#brief Variable length data encapsulation in terms of length and pointer to data */
typedef struct
{
uint8_t * p_data; /**< Pointer to data. */
uint16_t data_len; /**< Length of data. */
}data_t;
typedef enum
{
BLE_NO_SCAN, /**< No advertising running. */
BLE_WHITELIST_SCAN, /**< Advertising with whitelist. */
BLE_FAST_SCAN, /**< Fast advertising running. */
} ble_scan_mode_t;
static ble_db_discovery_t m_ble_db_discovery; /**< Structure used to identify the DB Discovery module. */
static ble_hrs_c_t m_ble_hrs_c; /**< Structure used to identify the heart rate client module. */
static ble_bas_c_t m_ble_bas_c; /**< Structure used to identify the Battery Service client module. */
static ble_gap_scan_params_t m_scan_param; /**< Scan parameters requested for scanning and connection. */
static dm_application_instance_t m_dm_app_id; /**< Application identifier. */
static dm_handle_t m_dm_device_handle; /**< Device Identifier identifier. */
static uint8_t m_peer_count = 0; /**< Number of peer's connected. */
static ble_scan_mode_t m_scan_mode = BLE_FAST_SCAN; /**< Scan mode used by application. */
static uint16_t m_conn_handle; /**< Current connection handle. */
static volatile bool m_whitelist_temporarily_disabled = false; /**< True if whitelist has been temporarily disabled. */
static bool m_memory_access_in_progress = false; /**< Flag to keep track of ongoing operations on persistent memory. */
/**
* #brief Connection parameters requested for connection.
*/
static const ble_gap_conn_params_t m_connection_param =
{
(uint16_t)MIN_CONNECTION_INTERVAL, // Minimum connection
(uint16_t)MAX_CONNECTION_INTERVAL, // Maximum connection
0, // Slave latency
(uint16_t)SUPERVISION_TIMEOUT // Supervision time-out
};
static void scan_start(void);
#define APPL_LOG app_trace_log /**< Debug logger macro that will be used in this file to do logging of debug information over UART. */
/**#brief Function for initializing the UART.
*/
static void uart_init(void)
{
uint32_t err_code;
const app_uart_comm_params_t comm_params =
{
RX_PIN_NUMBER,
TX_PIN_NUMBER,
RTS_PIN_NUMBER,
CTS_PIN_NUMBER,
APP_UART_FLOW_CONTROL_ENABLED,
false,
UART_BAUDRATE_BAUDRATE_Baud38400
};
APP_UART_FIFO_INIT(&comm_params,
UART_RX_BUF_SIZE,
UART_TX_BUF_SIZE,
uart_error_handle,
APP_IRQ_PRIORITY_LOW,
err_code);
APP_ERROR_CHECK(err_code);
app_trace_init();
}
/** #brief Function for the Power manager.
*/
static void power_manage(void)
{
uint32_t err_code = sd_app_evt_wait();
APP_ERROR_CHECK(err_code);
}
int main(void)
{
bool erase_bonds;
// Initialize.
uart_init();
printf("Heart rate collector example (this is a custom log)\r\n");
for (;; )
{
power_manage();
}
}
The problem I am having is that only sometimes I will see an output in GTKterm. I am unable to find a pattern for when it works and when it doesn't. How would I go about debugging this?

Answer 1

How would I go about debugging this?
Some suggestions for starters:
Ensure that your terminal software is asserting the DTR signal. That was the solution found here.
Temporarily remove the call to power_manage() to ensure that is not part of the problem.
Change APP_UART_FLOW_CONTROL_ENABLED for APP_UART_FLOW_CONTROL_DISABLED to determine whether it is a flow control issue. You will not need flow control for output to a PC in any case. It may be needed if you are inputting to the device (especially with a buffer length of 1) or if you are sending to data to a slow device with limited buffering.
Verify ERR_CODE after calling APP_UART_FIFO_INIT to ensure no problems occurred at that stage. Possible error codes are defined here.