Hello,
I try to configure two nrf52832 devices work with payload of 200 bytes (data should be 200 bytes, not the all ble packet).
I took ble_app_uart_c peripheral and central examples - for 20 bytes everything looks ok.
After that, I tried to understand and implement in my code the ble_app_att_mtu_throughput example, but without luck.
Where can I find the exact algorithm for the increasing the payload size?
My algorithm now:
Common definitions:
NRF_SDH_BLE_GATT_MAX_MTU_SIZE defined for 247 bytes (in sdk_config.h)
BLE_GATT_ATT_MTU_DEFAULT defined to 204 bytes (in ble_gatt.h)
Central:
in function ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context) - the function handles all BLE events
- in event BLE_GAP_EVT_PHY_UPDATE_REQUEST
-- I define the 2MBPS speed:
ble_gap_phys_t const phys =
{
.rx_phys = BLE_GAP_PHY_2MBPS,
.tx_phys = BLE_GAP_PHY_2MBPS,
};
sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
in function gatt_init() - the function initiates the gatt library
- nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
- nrf_ble_gatt_att_mtu_central_set(&m_gatt, BLE_GATT_ATT_MTU_DEFAULT); //to 204 bytes
in function data_len_ext_set() - the function should set the new MTU size. the function placed in main() function, after all initializations, but before scan_start() call
- nrf_ble_gatt_data_length_set(&m_gatt, BLE_CONN_HANDLE_INVALID, 200 + L2CAP_HDR_LEN); - according to example. 200 - needed payload, L2CAP_HDR_LEN - defined as 4
in function conn_evt_len_ext_set() - not sure, but looks that the function enables length increasing option in the stack, called just after the data_len_ext_set() function
- memset(&opt, 0x00, sizeof(opt));
- opt.common_opt.conn_evt_ext.enable = 1;
- sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);
Peripheral
in ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context) - the function handles all BLE events
- I define the 2MBPS speed:
ble_gap_phys_t const phys =
{
.rx_phys = BLE_GAP_PHY_2MBPS,
.tx_phys = BLE_GAP_PHY_2MBPS,
};
- in event BLE_GAP_EVT_CONNECTED
-- sd_ble_gap_phy_update(p_gap_evt->conn_handle, &phys); //request for 2MBPS
- in event BLE_GAP_EVT_PHY_UPDATE_REQUEST
-- sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
- in event BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST
-- memset(&dl_params, 0, sizeof(ble_gap_data_length_params_t));
-- sd_ble_gap_data_length_update(p_ble_evt->evt.gap_evt.conn_handle, &dl_params, NULL);
in function gatt_init() - the function initiates the gatt library
- nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
- nrf_ble_gatt_att_mtu_periph_set(&m_gatt, BLE_GATT_ATT_MTU_DEFAULT); //to 204 bytes
in function data_len_ext_set() - the function should set the new MTU size. the function placed in main() function, after all initializations, but before ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST); call
- nrf_ble_gatt_data_length_set(&m_gatt, BLE_CONN_HANDLE_INVALID, 200 + L2CAP_HDR_LEN); - according to example. 200 - needed payload, L2CAP_HDR_LEN - defined as 4
in function conn_evt_len_ext_set() - not sure, but looks that the function enables length increasing option in the stack, called just after the data_len_ext_set() function
- memset(&opt, 0x00, sizeof(opt));
- opt.common_opt.conn_evt_ext.enable = 1;
- sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);
So, is it looks ok? Some mistakes that you could point me on? Something is missing?
Thanks a lot!
