Bluetooth configuration disabled sensor trigger

[scottwan]

Hi Nordic,

when I enable the Bluetooth configuration, the sensor trigger stop to work. when I comment the Bluetooth configuration, the sensor trigger back to work.

I recorded the screen as below:

the expected result is the Bluetooth configuration will not have any negative effect to the function already developed.

[Hung Bui]

Hi Scott, 
I'm not sure if you need CONFIG_BT_HCI=y. If you simply do:
CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y

Would it work ?

Also please check if there is any timing issue with your sensor that the trigger stopped working ? Maybe you can check the SPI lines to see if there is any activity ? 

[scottwan]

Hi Hung,

It is same if ONLY enable BT and BT_PERIPHERAL, I will ckeck if SPI registers can be read properly after BT enabled in a polling loop.

How to check if there is any timing issue with the sensor that the trigger stopped working ?

[Hung Bui]

I would suggest to use a logic analyzer and hook it on the SPI lines to see if there is any activity. Does the CPU hang or only the SPI triggering function doesn't work ? If you initialize bluetooth would Bluetooth works as expected ? 

[scottwan]

Hi Hung,

I did not get a analyzer yet, but it seems not only sensor trigger effected, it seems the whole sensor was effected, because even in the main() while loop the sensor data can not be got. but the other sensor on the other SPI was NOT effected. 

The CPU did not hang, because console can output log in while loop in main().

If I initialize bluetooth, Bluetooth works as expected except the a error will raise when send byte more than 24 bytes, but it is ok when send only 20 bytes.

the eroor log can be seen MTU 27：

00> [00:01:22.663,757] <wrn> bt_att: No ATT channel for MTU 27
00> [00:01:22.663,757] <wrn> bt_gatt: No buffer available to send notification
00> Error, unable to send notification

For the BLE max length to send and receive I see already defined as 240, but did not seen where used this number, send 24 bytes will get error.

#define MAX_TRANSMIT_SIZE 240
    uint8_t data_rx[MAX_TRANSMIT_SIZE];
    uint8_t data_tx[MAX_TRANSMIT_SIZE];


int my_service_init(void)
{
    int err = 0;
   
    memset(&data_rx, 0, MAX_TRANSMIT_SIZE);
    memset(&data_tx, 0, MAX_TRANSMIT_SIZE);
    
    return err;
}

 

/* LED Button Service Declaration and Registration */
BT_GATT_SERVICE_DEFINE(my_service,
    BT_GATT_PRIMARY_SERVICE(BT_UUID_MY_SERVICE),
    BT_GATT_CHARACTERISTIC(BT_UUID_MY_SERVICE_RX,
                    BT_GATT_CHRC_WRITE | BT_GATT_CHRC_WRITE_WITHOUT_RESP,
                    BT_GATT_PERM_READ | BT_GATT_PERM_WRITE, 
                    NULL, on_receive, NULL),
    BT_GATT_CHARACTERISTIC(BT_UUID_MY_SERVICE_TX,
                    BT_GATT_CHRC_NOTIFY,
                    BT_GATT_PERM_READ,
                    NULL, NULL, NULL),
    BT_GATT_CCC(on_cccd_changed,
            BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
);

The BLE code I written was followed by Bluetooth low energy Services, a beginner's tutorial

[Hung Bui]

Hi Scott, 
The tutorial you quoted was very old and it's for the legacy nRF5 SDK not NRF Connect SDK. 

I would suggest to follow this or this.

I suspect a change in timing may cause an issue with your SPI sensor. A logic analyzer would really help to find what could be wrong. 
My understanding is that the SPI sensor would require some commands before it can provide the trigger/interrupt ? Please double check to see if the command(s) is sent. 

Regarding your question about the MTU size, you would need to configure CONFIG_BT_CTLR_DATA_LENGTH_MAX, CONFIG_BT_BUF_ACL_RX_SIZE and CONFIG_BT_BUF_ACL_TX_SIZE. I would suggest to have a look at the \nrf\samples\bluetooth\throughput example. 

[scottwan]

Hi Hung,

when I hook the logic analyzer on the SPI lines, I can see the SPI send data to sensor are correct whatever the Bluetooth subsystem is enabled or not. the problem is when the Bluetooth configuration added in prj.conf file, the sensor does not response, the data get always 0.

the SPI activity when Bluetooth config NOT added: 

the SPI activity when Bluetooth config added:

for the Bluetooth, the link gave is wrong, the guide I followed is exactly you sugged in last post. for the MTU limitation, I added the  CONFIG_BT_CTLR_DATA_LENGTH_MAX, CONFIG_BT_BUF_ACL_RX_SIZE and CONFIG_BT_BUF_ACL_TX_SIZE. the problem is same.

[Hung Bui]

Hi Scott, 

It's strange that the SPI sensor act differently when you enable Bluetooth or not. To avoid any timing issue, I would suggest to delay the initialization of SPI sensor, for example until you press a button. This way it should be exactly the same if you initialize Bluetooth or not. Please also check if VDD is provided to the SPI sensor correctly. 
Regarding the BLE notification of larger payload, please try to capture a sniffer trace.  
Note that at least on one side (central or peripheral) you need to call bt_conn_le_data_len_update() to update to higher data length. Please refer the throughput example that I pointed to. 

[scottwan]

Hi Hung,

the guide I followed to initialize SPI senor is Option 1: create devices using instance numbers

I think it is initiate automatically and can not be changed to initiate by press a button. 

Hung Bui said:

Please also check if VDD is provided to the SPI sensor correctly

since the sensor works fine when the Bluetooth configurations not enabled, why I have to check VDD to the sensor, there no any lines change when I enable Bluetooth.

[scottwan]

Hi Hung,

it is same even 'bt_conn_le_data_len_update()' called, no more than 20 bytes can send.

[Hung Bui]

Hi Wan, 

What I suspect was if there is any timing delay that would cause the issue. Please try to capture the logic trace of the whole process from the time you turn on the board, with and without Bluetooth enabled. 

It would be easier to explain if the sensor actually send the interrupt but the NRF53 chip doesn't catch it but in this case the sensor behaves differently with and without Bluetooth even with the same SPI input data. I would suggest to focus on what's the difference from the sensor's side when receiving the signal from the NRF53. 

Regarding the issue with max data length for notification, please capture a sniffer trace. Please double check what's the data length used in the connection (check the le_data_len_updated callback) 

[scottwan]

ble mtu issue solved by:

1) add 'CONFIG_BT_GATT_CLIENT=y' in prj.conf

2) call 'bt_gatt_exchange_mtu()' in ble connected callback function