Hello everyone,
I am developing an application, with the nRF52840 chip (actually BMD-380) , that streams via BLE data read by an SPI sensor (ADS1293) to an Ubuntu machine @ 250 Hz.
For testing purposes, I am sending only one byte with the "bt_hrs_notify" function when the data ready callback is triggered (250Hz verified with a logic analyzer) :
#include <zephyr.h>
#include <device.h>
#include "ads1293.h"
#include "ble_utils.h"
K_SEM_DEFINE(ADS_sem, 0, 1);
void data_ready_cb(const struct device *dev, struct gpio_callback *cb,
uint32_t pins)
{
k_sem_give(&ADS_sem);
}
void main(void)
{
init_ble();
init_ads1293(); // Init SPI drivers and GPIO ISR that triggers 'data_ready_cb'
int8_t dummy_byte = 10;
while (1)
{
k_sem_take(&threadADS_sem, K_FOREVER);
bt_hrs_notify(dummy_byte);
}
}
the other relevant .c file for BLE (taken from the zephyr peripheral HR example):
#include "ble_utils.h"
static const struct bt_data ad[] = {
BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
BT_DATA_BYTES(BT_DATA_UUID16_ALL,
BT_UUID_16_ENCODE(BT_UUID_HRS_VAL),
BT_UUID_16_ENCODE(BT_UUID_BAS_VAL),
BT_UUID_16_ENCODE(BT_UUID_DIS_VAL))
};
static void connected(struct bt_conn *conn, uint8_t err)
{
if (err) {
printk("Connection failed (err 0x%02x)\n", err);
} else {
printk("Connected\n");
}
}
static void disconnected(struct bt_conn *conn, uint8_t reason)
{
printk("Disconnected (reason 0x%02x)\n", reason);
}
BT_CONN_CB_DEFINE(conn_callbacks) = {
.connected = connected,
.disconnected = disconnected,
};
static void bt_ready(void)
{
int err;
printk("Bluetooth initialized\n");
err = bt_le_adv_start(BT_LE_ADV_CONN_NAME, ad, ARRAY_SIZE(ad), NULL, 0);
if (err) {
printk("Advertising failed to start (err %d)\n", err);
return;
}
printk("Advertising successfully started\n");
}
static void auth_cancel(struct bt_conn *conn)
{
char addr[BT_ADDR_LE_STR_LEN];
bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
printk("Pairing cancelled: %s\n", addr);
}
static struct bt_conn_auth_cb auth_cb_display = {
.cancel = auth_cancel,
};
void init_ble(void)
{
int err;
err = bt_enable(NULL);
if (err) {
printk("Bluetooth init failed (err %d)\n", err);
return;
}
bt_ready();
bt_conn_auth_cb_register(&auth_cb_display);
}
prj.conf:
CONFIG_STDOUT_CONSOLE=n CONFIG_SERIAL=n CONFIG_SPI=y CONFIG_SENSOR=y CONFIG_BT=y CONFIG_BT_DEBUG_LOG=y CONFIG_BT_SMP=y CONFIG_BT_PERIPHERAL=y CONFIG_BT_DIS=y CONFIG_BT_DIS_PNP=n CONFIG_BT_BAS=y CONFIG_BT_HRS=y CONFIG_BT_DEVICE_NAME="Test BLE" CONFIG_BT_DEVICE_APPEARANCE=833
with this basic configurations I obtain a throughput of just about 60Hz.
If I get rid of the timing given by the ISR, and so sending continuously data in the infinite while loop, this can reach up to 1500Hz, but I obviously need the timing given by the sensor.
Is there something I am missing? Do you have any idea on how to improve the communication?
Thank you very much for your time!
