Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

moon.kim — Fri, 11 Oct 2019 09:32:21 GMT

You are right.
It is more effective to use the TX_COMPLETE event than to change the queue size. Although errors still occur, they are not as bad as you say.
The problem that was not transmitted when the most problematic RACP_OPERATOR_ALL was called continuously was resolved.

Thank you!!

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

Susheel Nuguru — Fri, 11 Oct 2019 08:02:01 GMT

well setting it too large with a very large RAM size would be good to achieve high throughput, but the RAM size is limited on our devices due to cost balancing.

What number is good depends on your use case and there no standard answer for that. Getting NRF_ERROR_RESOURCES on many applications is not a bad thing. Apps could wait until they get the TX_COMPLETE event and resume transmission without increasing the tx buffer size linearly.

In your case, with RACP, you should do few benchmarking tests to see which buffer size suits your app correctly.

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

moon.kim — Thu, 10 Oct 2019 08:24:36 GMT

Thank you.
I am using SDK Version 15.0.0. I tried to modify RAM_SIZE as you told me, but I didn't.

So I solved it as follows.
I'm using IAR EWARM.

RAM_START of nrf_sdh_ble.c has not been changed.
RAM_START = 0x20000000

In the ble_app_gls_iar_nRF5x.icf file, the following changes were made:

//define symbol __ICFEDIT_region_RAM_start__   = 0x20001b48;
define symbol __ICFEDIT_region_RAM_start__   = 0x20001E30;
define symbol __ICFEDIT_region_RAM_end__     = 0x20005fff;

There is still NRF_ERROR_RESOURCES, but it has decreased a lot.

How do I know the right size of the queue size? If set too large, it will malfunction.

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

Susheel Nuguru — Wed, 09 Oct 2019 11:04:49 GMT

When i applied your changes, then i got some debug logs on the UART as below

I changed the start of the RAM as below, everything worked normally after that.

RAM_START=0x200028E0
RAM_SIZE=0xd720

FYI,

I tested this on nRF52832, so the numbers might be different for you since you are using nRF52810 and a different softdevice.

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

moon.kim — Fri, 04 Oct 2019 01:37:06 GMT

I changed to below...

#define NRF_SDH_BLE_GAP_EVENT_LENGTH 10
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 100

This change causes an error.

So I did not change the event handler and MTU size.

and As you said, I changed hvn_tx_queue_size.

ble_cfg_t ble_cfg;
memset(&ble_cfg, 0, sizeof ble_cfg);
ble_cfg.conn_cfg.conn_cfg_tag = APP_BLE_CONN_CFG_TAG;
ble_cfg.conn_cfg.params.gatts_conn_cfg.hvn_tx_queue_size = 10;
Err_code = sd_ble_cfg_set(BLE_CONN_CFG_GATTS, &ble_cfg, ram_start);
APP_ERROR_CHECK(Err_code);

However, an error also occurs in sd_ble_enable.

And I have no limit on the MTU size.

I need to send up to 500EA GLS Measurement and Context data.

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

Susheel Nuguru — Wed, 02 Oct 2019 08:06:49 GMT

What are the event length and MTU size you are using n your sdk_config.h?

The NRF_ERROR_RESOURCES is based on TX buffer queue and could be increased from default as shown here.

Do you have specific limitations on how small the MTU size can be?

RE: Changing NRF_SDH_BLE_GATT_MAX_MTU_SIZE causes an error.

moon.kim — Tue, 01 Oct 2019 01:16:16 GMT

This only happens in the nRF toolbox for Android and the NRF_ERROR_RESOURCES in the nRF toolbox for iOS. However, multiple calls to RACP_OPERATOR_ALL can send data.