I’m writing BLE UART code.
When BLE is not connected, current consumption is ~30 µA.
But when BLE is connected, consumption increases by ~1 mA.
I want to reduce the current during an active BLE connection—ideally back toward the disconnected level.
Is that theoretically possible? What suggestions do you have?
#include <stdio.h>
#include "nordic_common.h"
#include "nrf.h"
#include "ble_hci.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "app_timer.h"
#include "ble_nus.h"
#include "app_uart.h"
#include "app_util_platform.h"
#include "bsp_btn_ble.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_drv_saadc.h"
#include "app_error.h"
//#include "nrf_delay.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_timer.h"
#include "nrf_gpio.h"
#include "nrfx_rtc.h"
#include "nrf_drv_clock.h"
#include "nrf_drv_rtc.h"
#include "nrf_soc.h"
#include "nrf_nvic.h"
#include "app_error.h"
#include "app_util_platform.h"
#include "nrf_pwr_mgmt.h"
#include "app_error.h"
#include "nrf_drv_clock.h"
#include "nrf_nvmc.h"
#if defined (UART_PRESENT)
#include "nrf_uart.h"
#endif
#if defined (UARTE_PRESENT)
#include "nrf_uarte.h"
#endif
#include "boards.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
//#include "nrf_log_default_backends.h"
//#define ADC_UPDATE_INTERVAL_MIN 1 // ADC update interval in minutes
//#define TICK_INTERVAL_MS 125
//#define TOTAL_TICKS ((ADC_UPDATE_INTERVAL_MIN * 60000) / TICK_INTERVAL_MS)
//const nrfx_rtc_t rtc = NRFX_RTC_INSTANCE(2);
//volatile uint32_t tick_count = 0; // Tick counter
//nrf_saadc_value_t adc_val;
//nrf_saadc_value_t adc_save[360]; // Array to store ADC samples
//uint16_t i = 0;
#define APP_BLE_CONN_CFG_TAG 1 /**< A tag identifying the SoftDevice BLE configuration. */
#define DEVICE_NAME "MAyur_Nordic" /**< Name of device. Will be included in the advertising data. */
#define NUS_SERVICE_UUID_TYPE BLE_UUID_TYPE_VENDOR_BEGIN /**< UUID type for the Nordic UART Service (vendor specific). */
#define APP_BLE_OBSERVER_PRIO 3 /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_ADV_INTERVAL 1600//64 /**< The advertising interval (in units of 0.625 ms. This value corresponds to 40 ms). */
#define APP_ADV_DURATION 6000//18000 /**< The advertising duration (180 seconds) in units of 10 milliseconds. */
#define MIN_CONN_INTERVAL MSEC_TO_UNITS(300, UNIT_1_25_MS) //100 //200 /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(400, UNIT_1_25_MS) //200 //400 /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */
#define SLAVE_LATENCY 2//4//0 /**< Slave latency. */
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */
#define FIRST_CONN_PARAMS_UPDATE_DELAY APP_TIMER_TICKS(5000) /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY APP_TIMER_TICKS(30000) /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT 3 /**< Number of attempts before giving up the connection parameter negotiation. */
#define DEAD_BEEF 0xDEADBEEF /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */
#define UART_TX_BUF_SIZE 256 /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE 256 /**< UART RX buffer size. */
BLE_NUS_DEF(m_nus, NRF_SDH_BLE_TOTAL_LINK_COUNT); /**< BLE NUS service instance. */
NRF_BLE_GATT_DEF(m_gatt); /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr); /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising); /**< Advertising module instance. */
static uint16_t m_conn_handle = BLE_CONN_HANDLE_INVALID; /**< Handle of the current connection. */
static uint16_t m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - 3; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */
static ble_uuid_t m_adv_uuids[] = /**< Universally unique service identifier. */
{
{BLE_UUID_NUS_SERVICE, NUS_SERVICE_UUID_TYPE}
};
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name);
static void timers_init(void);
static void gap_params_init(void);
static void nrf_qwr_error_handler(uint32_t nrf_error);
static void nus_data_handler(ble_nus_evt_t * p_evt);
static void services_init(void);
static void on_conn_params_evt(ble_conn_params_evt_t * p_evt);
static void conn_params_error_handler(uint32_t nrf_error);
static void conn_params_init(void);
static void on_adv_evt(ble_adv_evt_t ble_adv_evt);
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context);
static void ble_stack_init(void);
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt);
void gatt_init(void);
void uart_event_handle(app_uart_evt_t * p_event);
static void uart_init(void);
static void advertising_init(void);
static void log_init(void);
static void advertising_start(void);
void idle_state_handle()
{
__WFE(); // Wait for event (low-power)
__SEV(); // Set event (in case event missed)
__WFE(); // Wait again to enter sleep
}
void uart_disable(void)
{
app_uart_close(); // Closes UART FIFO and disables interrupts
}
int main(void)
{
// NRF_POWER->DCDCEN = 1; // Enable DC/DC converter
timers_init();
ble_stack_init(); // ble work that time nvmc is not work. for data save.
gap_params_init();
gatt_init();
services_init();
advertising_init();
conn_params_init();
advertising_start();
printf("application start");
for (;;)
{
idle_state_handle();
}
}
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
app_error_handler(DEAD_BEEF, line_num, p_file_name);
}
static void timers_init(void)
{
ret_code_t err_code = app_timer_init();
APP_ERROR_CHECK(err_code);
}
static void gap_params_init(void)
{
uint32_t err_code;
ble_gap_conn_params_t gap_conn_params;
ble_gap_conn_sec_mode_t sec_mode;
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
err_code = sd_ble_gap_device_name_set(&sec_mode,
(const uint8_t *) DEVICE_NAME,
strlen(DEVICE_NAME));
APP_ERROR_CHECK(err_code);
memset(&gap_conn_params, 0, sizeof(gap_conn_params));
gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
gap_conn_params.slave_latency = SLAVE_LATENCY;
gap_conn_params.conn_sup_timeout = CONN_SUP_TIMEOUT;
err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
APP_ERROR_CHECK(err_code);
}
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
APP_ERROR_HANDLER(nrf_error);
}
//static void nus_data_handler(ble_nus_evt_t * p_evt)
//{
// // A variable to hold the error code FOR THE
// if (p_evt->type == BLE_NUS_EVT_RX_DATA)
// {
// uint32_t err_code;
// uint8_t data[200];
// // NRF_LOG_DEBUG("Received data from BLE NUS. Writing data on UART.");
// NRF_LOG_HEXDUMP_DEBUG(p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);
// for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++)
// {
// do
// {
// err_code = app_uart_put(p_evt->params.rx_data.p_data[i]);
// if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY))
// {
// //NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
// APP_ERROR_CHECK(err_code);
// }
// } while (err_code == NRF_ERROR_BUSY);
// }
// if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r')
// {
// while (app_uart_put('\n') == NRF_ERROR_BUSY);
// }
// }
//}
static void nus_data_handler(ble_nus_evt_t * p_evt)
{
if (p_evt->type == BLE_NUS_EVT_RX_DATA)
{
uint8_t data[200];
uint8_t data1[20];
// Copy received data and null-terminate
memcpy(data, p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);
data[p_evt->params.rx_data.length] = '\0';
// ✅ Print received data over BLE
printf("Received over BLE: %s\n", data);
sprintf((char *)data1, "ADC: %s", data);
uint16_t length = strlen((char *)data1);
uint32_t err_code = ble_nus_data_send(&m_nus, data, &length, m_conn_handle);
if (err_code == NRF_SUCCESS)
{
printf("Sent over BLE: %s\n", data1); // Print confirmation on SES Terminal
}
else
{
printf("BLE Send Error: %d\n", err_code);
}
// ✅ Optional: Echo back to UART (if needed)
for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++)
{
while (app_uart_put(p_evt->params.rx_data.p_data[i]) == NRF_ERROR_BUSY);
}
// Add newline if '\r' was last character
if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r')
{
while (app_uart_put('\n') == NRF_ERROR_BUSY);
}
}
}
static void services_init(void)
{
uint32_t err_code;
ble_nus_init_t nus_init;
nrf_ble_qwr_init_t qwr_init = {0};
// Initialize Queued Write Module.
qwr_init.error_handler = nrf_qwr_error_handler;
err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
APP_ERROR_CHECK(err_code);
// Initialize NUS.
memset(&nus_init, 0, sizeof(nus_init));
nus_init.data_handler = nus_data_handler;
err_code = ble_nus_init(&m_nus, &nus_init);
APP_ERROR_CHECK(err_code);
}
static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
{
uint32_t err_code;
if (p_evt->evt_type == BLE_CONN_PARAMS_EVT_FAILED)
{
err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
APP_ERROR_CHECK(err_code);
}
}
static void conn_params_error_handler(uint32_t nrf_error)
{
APP_ERROR_HANDLER(nrf_error);
}
static void conn_params_init(void)
{
uint32_t err_code;
ble_conn_params_init_t cp_init;
memset(&cp_init, 0, sizeof(cp_init));
cp_init.p_conn_params = NULL;
cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
cp_init.next_conn_params_update_delay = NEXT_CONN_PARAMS_UPDATE_DELAY;
cp_init.max_conn_params_update_count = MAX_CONN_PARAMS_UPDATE_COUNT;
cp_init.start_on_notify_cccd_handle = BLE_GATT_HANDLE_INVALID;
cp_init.disconnect_on_fail = false;
cp_init.evt_handler = on_conn_params_evt;
cp_init.error_handler = conn_params_error_handler;
err_code = ble_conn_params_init(&cp_init);
APP_ERROR_CHECK(err_code);
}
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
uint32_t err_code;
switch (ble_adv_evt)
{
case BLE_ADV_EVT_FAST:
idle_state_handle();
break;
case BLE_ADV_EVT_IDLE:
// sleep_mode_enter();
//sd_power_system_off();
advertising_start(); // Restart advertising
break;
default:
break;
}
}
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
uint32_t err_code;
switch (p_ble_evt->header.evt_id)
{
case BLE_GAP_EVT_CONNECTED:
// NRF_LOG_INFO("Connected")
m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
APP_ERROR_CHECK(err_code);
uart_init();
break;
case BLE_GAP_EVT_DISCONNECTED:
//NRF_LOG_INFO("Disconnected");
// LED indication will be changed when advertising starts.
m_conn_handle = BLE_CONN_HANDLE_INVALID;
uart_disable();
//sd_power_system_off(); // Power down
idle_state_handle();
break;
case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
{
//NRF_LOG_DEBUG("PHY update request.");
ble_gap_phys_t const phys =
{
.rx_phys = BLE_GAP_PHY_AUTO,
.tx_phys = BLE_GAP_PHY_AUTO,
};
err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
APP_ERROR_CHECK(err_code);
} break;
case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
// Pairing not supported
err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
APP_ERROR_CHECK(err_code);
break;
case BLE_GATTS_EVT_SYS_ATTR_MISSING:
// No system attributes have been stored.
err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
APP_ERROR_CHECK(err_code);
break;
case BLE_GATTC_EVT_TIMEOUT:
// Disconnect on GATT Client timeout event.
err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
APP_ERROR_CHECK(err_code);
break;
case BLE_GATTS_EVT_TIMEOUT:
// Disconnect on GATT Server timeout event.
err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
APP_ERROR_CHECK(err_code);
break;
default:
// No implementation needed.
break;
}
}
static void ble_stack_init(void)
{
ret_code_t err_code;
err_code = nrf_sdh_enable_request();
APP_ERROR_CHECK(err_code);
// Configure the BLE stack using the default settings.
// Fetch the start address of the application RAM.
uint32_t ram_start = 0;
err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
APP_ERROR_CHECK(err_code);
// Enable BLE stack.
err_code = nrf_sdh_ble_enable(&ram_start);
APP_ERROR_CHECK(err_code);
// Register a handler for BLE events.
NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
if ((m_conn_handle == p_evt->conn_handle) && (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED))
{
m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
// NRF_LOG_INFO("Data len is set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
}
//NRF_LOG_DEBUG("ATT MTU exchange completed. central 0x%x peripheral 0x%x",
// p_gatt->att_mtu_desired_central,
// p_gatt->att_mtu_desired_periph);
}
void gatt_init(void)
{
ret_code_t err_code;
err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
APP_ERROR_CHECK(err_code);
err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
APP_ERROR_CHECK(err_code);
}
void uart_event_handle(app_uart_evt_t * p_event)
{
static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
static uint8_t index = 0;
uint32_t err_code;
switch (p_event->evt_type)
{
case APP_UART_DATA_READY:
UNUSED_VARIABLE(app_uart_get(&data_array[index]));
index++;
if ((data_array[index - 1] == '\n') ||
(data_array[index - 1] == '\r') ||
(index >= m_ble_nus_max_data_len))
{
if (index > 1)
{
//NRF_LOG_DEBUG("Ready to send data over BLE NUS");
NRF_LOG_HEXDUMP_DEBUG(data_array, index);
do
{
uint16_t length = (uint16_t)index;
err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);
if ((err_code != NRF_ERROR_INVALID_STATE) &&
(err_code != NRF_ERROR_RESOURCES) &&
(err_code != NRF_ERROR_NOT_FOUND))
{
APP_ERROR_CHECK(err_code);
}
} while (err_code == NRF_ERROR_RESOURCES);
}
index = 0;
}
break;
case APP_UART_COMMUNICATION_ERROR:
APP_ERROR_HANDLER(p_event->data.error_communication);
break;
case APP_UART_FIFO_ERROR:
APP_ERROR_HANDLER(p_event->data.error_code);
break;
default:
break;
}
}
static void uart_init(void)
{
uint32_t err_code;
app_uart_comm_params_t const comm_params =
{
.rx_pin_no = RX_PIN_NUMBER,
.tx_pin_no = TX_PIN_NUMBER,
.rts_pin_no = RTS_PIN_NUMBER,
.cts_pin_no = CTS_PIN_NUMBER,
.flow_control = APP_UART_FLOW_CONTROL_DISABLED,
.use_parity = false,
#if defined (UART_PRESENT)
.baud_rate = NRF_UART_BAUDRATE_115200
#else
.baud_rate = NRF_UARTE_BAUDRATE_115200
#endif
};
APP_UART_FIFO_INIT(&comm_params,
UART_RX_BUF_SIZE,
UART_TX_BUF_SIZE,
uart_event_handle,
APP_IRQ_PRIORITY_LOWEST,
err_code);
APP_ERROR_CHECK(err_code);
NRF_P0->PIN_CNF[RX_PIN_NUMBER] |= GPIO_PIN_CNF_PULL_Msk;
}
/**@snippet [UART Initialization] */
/**@brief Function for initializing the Advertising functionality.
*/
static void advertising_init(void)
{
uint32_t err_code;
ble_advertising_init_t init;
memset(&init, 0, sizeof(init));
init.advdata.name_type = BLE_ADVDATA_FULL_NAME;
init.advdata.include_appearance = false;
init.advdata.flags = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;
init.srdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
init.srdata.uuids_complete.p_uuids = m_adv_uuids;
init.config.ble_adv_fast_enabled = true;
init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
init.config.ble_adv_fast_timeout = APP_ADV_DURATION;
init.evt_handler = on_adv_evt;
err_code = ble_advertising_init(&m_advertising, &init);
APP_ERROR_CHECK(err_code);
ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}
/**@brief Function for starting advertising.
*/
static void advertising_start(void)
{
uint32_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
APP_ERROR_CHECK(err_code);
}
