How to increase the MTU size in NRF52833?

[lara]

I have tried the below in proj.conf.iam using NRF52833 DK in VS CODE(NRF SDK Connect extension.Iam trying to receive data through gatt protocol,but it is not receiving more than 20 bytes.

toolchain version 2.8

also my build log showing ...

Memory region         Used Size  Region Size  %age Used
           FLASH:      203344 B       248 KB     80.07%
             RAM:       29188 B        32 KB     89.07%
        IDT_LIST:          0 GB        32 KB      0.00%

according to datasheet..512 KB Flash + 128 KB RAM for NRF52833DK.but the build log showing only 32kB of RAM,248kB of Flash.why?

CONFIG_BT_USER_DATA_LEN_UPDATE=y

CONFIG_BT_L2CAP_TX_MTU=247

CONFIG_BT_BUF_ACL_TX_SIZE=251

CONFIG_BT_BUF_ACL_RX_SIZE=251

[Simonr]

Hi

This is because the nRF Connect SDK sets region sizes for your application that aren't necessarily using the full flash/RAM of your devices. Have you for example enabled debugging in your configs, or are you using MCUBoot? You can check out the Memory footprint optimization documentation available here to see how to change these region sizes.

Best regards,

Simon

[lara]

understood..prj_minimal.conf contains...

CONFIG_BT_RX_STACK_SIZE=1024

CONFIG_BT_HCI_TX_STACK_SIZE_WITH_PROMPT=y

CONFIG_BT_HCI_TX_STACK_SIZE=640

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=1536

CONFIG_MPSL_WORK_STACK_SIZE=640

CONFIG_MAIN_STACK_SIZE=1024

CONFIG_IDLE_STACK_SIZE=128

CONFIG_ISR_STACK_SIZE=1024

# Disable features not needed

CONFIG_TIMESLICING=n

CONFIG_COMMON_LIBC_MALLOC=n

CONFIG_LOG=n

CONFIG_ASSERT=n

# Disable Bluetooth features not needed

CONFIG_BT_DEBUG_NONE=y

CONFIG_BT_ASSERT=n

CONFIG_BT_DATA_LEN_UPDATE=n

CONFIG_BT_PHY_UPDATE=n

CONFIG_BT_GATT_CACHING=n

CONFIG_BT_GATT_SERVICE_CHANGED=n

CONFIG_BT_GAP_PERIPHERAL_PREF_PARAMS=n

CONFIG_BT_SETTINGS_CCC_LAZY_LOADING=y

CONFIG_BT_HCI_VS=n

# Disable Bluetooth controller features not needed

CONFIG_BT_CTLR_PRIVACY=n

CONFIG_BT_CTLR_PHY_2M=n

# Reduce Bluetooth buffers

CONFIG_BT_BUF_EVT_DISCARDABLE_COUNT=1

CONFIG_BT_BUF_EVT_DISCARDABLE_SIZE=43

CONFIG_BT_BUF_EVT_RX_COUNT=2

CONFIG_BT_CONN_TX_MAX=3

CONFIG_BT_L2CAP_TX_BUF_COUNT=2

CONFIG_BT_ATT_TX_COUNT=2

CONFIG_BT_BUF_ACL_TX_COUNT=3

CONFIG_BT_BUF_ACL_TX_SIZE=27

partitions.yml

app:
  address: 0x0
  end_address: 0x3e000
  region: flash_primary
  size: 0x3e000
settings_storage:
  address: 0x3e000
  end_address: 0x40000
  placement:
    align:
      start: 0x1000
    before:
    - end
  region: flash_primary
  size: 0x2000
sram_primary:
  address: 0x20000000
  end_address: 0x20008000
  region: sram_primary
  size: 0x8000

can you little elaborate on this?

also i couldnot exceed mtu payload size more than 62 bytes..