Hello,
Hope you are doing well.
The DSB module captures data from the Radio interface and optionally transfers it via DMA to any given system memory address. This address is configurable in DADDR register. The data is also available in RDATA register.
The DSB contains an internal FIFO of 32 elements of 32 bits each. This can be verified in WMC[SIZE]. WMC[WMRK] configures the FIFO level at which the DMA transfer gets triggered.
See KW45 Reference Manual Chapter 56 Data Stream Buffer (DSB) for the memory map, register definitions and initialization/application information.
Though there are no APIs to control this module, all of its registers are available to the main core (CM33) to control the transfer, defined in PERI_DSB.h
There is also an option to enable interrupts for DMA transfer completion and data ready, handled by an IRQ in the main core called DSB_IRQHandler.
In BLE applications, if you need to transmit more than 245 bytes of data, it's necessary to implement mechanisms that go beyond the default ATT payload size. While the maximum attribute value size defined in the GATT database on a GATT Server (usually a BLE peripheral device) is 512 bytes, the actual data transfer is constrained by the negotiated MTU size.
You can find more information about this on the following community posts:
Bluetooth Low Energy - Working with long attributes on a GATT Server - Part 1: ATT_MTU
Bluetooth Low Energy - Working with long attributes on a GATT Server - Part 3: Writing long attribut...
Best Regards,
Ana Sofia.
