Characteristics count and TX ressources

[Cyril]

Hello everyone,

I have a device with a custom service including 3 characteristics and another device with 4 characteristics (same 3 chars as the first device + 1 new).

When I sync data continuously on the same char for both devices (as soon as BLE_GATTS_EVT_HVN_TX_COMPLETE is received, I send a new packet), I have 30% TX failure rate due to NRF_ERROR_RESOURCES on the device with 3 chars. However, on the device with 4 chars, I have 50% TX failure rate with same error: NRF_ERROR_RESOURCES.
I am not trying to send more data on the second device. Actually, the data is being sent a bit less often looking at the timestamps.

Is there a link between char count and TX buffer size?

Maybe bandwidth occupation?

Best,

[Mttrinh]

Hi,

I don't think there should be any link between the characteristics count and TX buffer size. Have you seen ths post regarding the NRF_ERROR_RESOURCES error?

[Cyril]

Hello,

I performed data sync on both devices, using the same phone, and logged into a CSV file:

characteristic number (0, 1 or 2), timestamp with hundredth, err_code

Both have a MTU of 120 bytes.

As I said before, packets are sent on BLE_GATTS_EVT_HVN_TX_COMPLETE event.

Device with 3 data chars has way more errors:

nRF52840

SD: s140_nrf52_6.0.0_softdevice.hex

SDK 15.0
output_s_OP3T_char2notsubscribed.csv

Device with 2 data char:

nRF52832
SD s132_nrf52_4.0.2_softdevice.hex

SDK 13.0

output_OP6.csv

How is it possible to have that many NRF_ERROR_RESOURCES on the device with 3 data chars?

Best,

Cyril