BTLE_CONNECTION_TIMEOUT while connection interval is small

[zhao]

Hi experts,

I need nrf51822 to send thousands of packets (notification) to Master Control Panel (PC), and expect for high data rate. So, I turned the connection interval from 100 ms to 20 ms in Master Control Panel. Unfortunately, the connection is broken after about 5 seconds. Everything is ok if the connection interval is 100ms.

my device configuration is like #define MIN_CONN_INTERVAL MSEC_TO_UNITS(10, UNIT_1_25_MS) #define MAX_CONN_INTERVAL MSEC_TO_UNITS(200, UNIT_1_25_MS) #define SLAVE_LATENCY 10
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(5000, UNIT_10_MS)

It seems the reason of timeout is I can't send packets as soon as possible. While the connection interval is 20 ms, the actual data rate is about 30 packets per seconds. The low data rate should be because I need read data from SPI Flash for sending.

I'm very confused why it happened. If I didn't send any notification, the connection was always on; but it timeout if I sent notification not fast enough.

Wondering for your help!

[zhao]

Thanks, Petter. Yes, it ran ok if I didn't read from SPI. In my project, I repeatedly read 19 bytes from SPI Flash and send it in notification packet, when the Master write a command. If I comment the read_spi function, it works fine. I did another experiment, in which, I didn't send the packets and tried to read out all the data (about one thousand of records, each is 19 bytes). I found the link will timeout also before all the data had been read out. The code seems be cancelled, because it can't reach the breakpoint below the read lines. I stop the simulator, and found cpu is running sd_app_evt_wait() in power_manage(). here is my code:

when Master write the command, I will call send_one_package to send the records to Master:

static INLINE uint32_t send_one_package() {
data_frame_t frame;
uint32_t err_code;
frame.header = FRAME_HEADER;
frame.type = FRAME_TYPE_HIST;
for (; pack_report.current_rec < pack_report.current_pack_len; pack_report.current_rec++) {
if (1 == fetch_a_record((uint8_t *)&(frame.record), pack_report.current_pack, pack_report.current_rec)) {
frame.record.csum += FRAME_PRE_CSUM_HIST;
err_code = ble_send((uint8_t *)&frame, DATA_FRAME_SIZE);     
if (err_code == BLE_ERROR_NO_TX_BUFFERS) {
    ble_tx_complete_handler_set(send_one_package);
    break;
  } else if ( err_code == NRF_ERROR_INVALID_STATE || 
              err_code == BLE_ERROR_GATTS_SYS_ATTR_MISSING) {
    ble_tx_complete_handler_set(send_one_package);      
    break;
  } else if (err_code != NRF_SUCCESS) {
    APP_ERROR_HANDLER(err_code);
  }
}
}
return err_code;
}

where the fetch_a_record is the function to read SPI Flash. If I comment this, everything is ok.

int8_t fetch_a_record(record_array_t rec_arr, package_no_t package, record_no_t rec) {
  record_t *record = (record_t *)rec_arr;
  address_t addr;
  addr = cal_record_address(package, rec);
  SPI_FLASH_BufferRead(rec_arr, addr, RECORD_LEN);
  return 1;
}

The flash read function is :

void SPI_FLASH_BufferRead(uint8_t* pBuffer, uint32_t ReadAddr, uint16_t NumByteToRead) {
  SPI_FLASH_CS_LOW();
  SPI_FLASH_SendByte(Read_Data);
  SPI_FLASH_SendByte((ReadAddr & 0xFF0000) >> 16);
  SPI_FLASH_SendByte((ReadAddr& 0xFF00) >> 8);
  SPI_FLASH_SendByte(ReadAddr & 0xFF);
  while(NumByteToRead--) {
    *pBuffer = SPI_FLASH_ReceiveByte();
    pBuffer++;
  }
  SPI_FLASH_CS_HIGH();
}

uint8_t SPI_FLASH_ReceiveByte(void) {
  return (SPI_FLASH_SendByte(Dummy_Byte));
}

ble_tx_complete_handler_set() will set the handler, which will be called in BLE_EVT_TX_COMPLETE event. So, I can send all the records repeatedly.

I failed to upload the entire project for the weak network. Please have a look if the above code can help. I will try it later.

BTW, I saw in ble_flash.c, there is

static void flash_word_write(uint32_t * p_address, uint32_t value) {
    // If radio is active, wait for it to become inactive.
    while (m_radio_active)     {
        // Do nothing (just wait for radio to become inactive).
        (void) sd_app_evt_wait();
    }
...
}

Should I also wait for the radio to be inactive when I access the flash?

Thanks a lot!