Peripheral fault from DLE with s132 v3.0?

[Elias]

I'm trying to maximize BLE throughput between a central and peripheral (I'm programming both) running the new s132 SoftDevice v3.0. I can't achieve the maximum data payload that I expect.

Following the migration document, I added the ATT_MTU exchange procedure and the Data Packet Length Extension, setting the MTU and the PDU to 251 on both sides, and I enabled Connection Event Length Extension. I also increased the size of the characteristic being written to 251 and set the Central's transmit bandwidth to high.

My current issue is that when I call sd_ble_gattc_write() on the Central with more than 62 bytes, the Peripheral hits some fault before the application receives the event. Even though my sniffer doesn't like extended packets, it seems to suggest that the Central is sending them properly, so the problem does seem to be with the Peripheral's SoftDevice. Are there any more obscurely documented modifications I should have made during my migration? Using a fault handler gives me no good info and I'm not using an IDE so I can't look at a call stack or anything.

By the way, are there updated serial port examples (a central and a peripheral) on the way? The ones in SDK12 have been updated to the new API, but they don't look like they exploit the new SD features.

[Petter Myhre]

I will look into this first thing Monday.

[Petter Myhre]

Here are examples of ATT MTU exchange and DLE.

I modified ble_app_uart and ble_app_uart_c. You should be able to send up to 155 bytes of data in one packet.

Use two terminals to send and receive data.

Here is a ZIP.

[eyeye]

Hi @Petter, I have try your examples on two nRF52-DK. It works as expected, the ATT_MTU and LL Data length extended. When I replace the central nRF52-DK with my iPhone6(iOS10), only ATT_MTU exchanged, LL Data length doesn't extended. nRF52 response the LL_LENGTH_REQ cmd with LL_UNKNOWN_RSP. It should be LL_LENGTH_RSP.

from this question you can get more detail information.

[Elias]

I haven't managed to go through the example completely, but making the modification to ble_stack_handler_types.h allowed me to double packet size and increase application throughput by about 100kb/s immediately, so I'll consider my issue resolved for now.

[Eugene]

Why is NRF_BLE_MAX_MTU_SIZE restricted by 158 bytes value? When i change it to 247 it failures with code 4 during soft device activation. What causes it?