CCS/CC2652R: Relation between HCI and NPI

Frederic Griffe

Part Number: CC2652R
Other Parts Discussed in Thread: CC2640R2F, CC2650

Tool/software: Code Composer Studio

Hello,

Both HCI and NPI are related to the communication between a host processor and a network processor or Wireless MCU acting as network processor.

So I would like to understand the relation or differences between HCI and NPI

Kind regards.

Frederic

over 3 years ago

0 Eirik V over 3 years ago

TI__Guru 56590 points

Hello Frederic Griffe,

The host controller interface (HCI) layer is a thin layer which transports commands and events between the host and controller elements of the Bluetooth protocol stack:

http://dev.ti.com/tirex/explore/content/simplelink_cc13x2_26x2_sdk_4_10_00_78/docs/ble5stack/ble_user_guide/html/ble-stack-5.x/hci.html?highlight=hci#host-controller-interface-hci

While NPI is TI’s Network Processor Interface (NPI) is used for establishing a serial data link between a TI SoC and external MCUs or PCs to send and receive HCI commands as well as a few custom commands.

http://dev.ti.com/tirex/explore/content/simplelink_cc13x2_26x2_sdk_4_10_00_78/docs/ble5stack/ble_user_guide/html/ble-stack-common/npi-index.html?highlight=npi#network-processor-interface-npi

Does that help?

0 Frederic Griffe over 3 years ago in reply to Eirik V

Expert 1715 points

Hello Eirik,

Thanks for the explanation, this makes it clearer.

In the Ti NPI user guide it is well explained what is installed on the network processor Wireless MCU to get the NPI RTOS Task. We also have the host-test example which explains the Network processor side.

But I would like to know what layers are required on the host side if we are using a CC3235 as host instead of a PC as shown in the examples.

Kind regards.

Frederic

0 Eirik V over 3 years ago in reply to Frederic Griffe

TI__Guru 56590 points

Hello Frederic,

This wiki post describe provide an older overview. But the SimpleNP is only implemented for CC2640R2F and not CC26x2:

https://processors.wiki.ti.com/index.php?oldid=222077&title=CC2640_BLE_Network_Processor&keyMatch=NETWORKPROCESSOR&tisearch=Search-EN-everything

Maybe this can be of use for you (ble_wifi_provisioning on CC3220) :

http://dev.ti.com/tirex/explore/node?node=ACs.0zeCfnQ5zR0-bnRKqw__kmPly-e__LATEST

There are different possible solutions on the network processor side to consider:

Network Processor (HostTest).
- Resources are BTool and the TI BLE Vendor Specific HCI Guide and possibly HCITester.
Network Processor DGATT_DB_OFF_CHIP (HostTest).
- No additional resource or example available. This can be complex.
Network Processor Custom ((HostTest with custom profiles and custom HCI commands).
- In some cases the easiest option where you simply add your BLE profiles and behavior into the HostTest project and add custom NPI commands and callbacks. In this case the GATT requests and operations can work autonomously on the network processor.
Stand Alone App with Serial Interface ( example project + custom serial)
- Simply add a simple serial interface on top of you embedded application.

An older wiki post on the topic:

https://processors.wiki.ti.com/index.php/CC254X_WITH_EXT_MCU

0 Frederic Griffe over 3 years ago in reply to Eirik V

Expert 1715 points

Hello Eirik,

Thanks a lot for the information.

In our application the Application processor will be the CC3235 and act as a BLE central device.

It will be connected to a CC2652 or CC2650 or even CC1352(we don't know yet be cause we want to test network communication with SubGHz also).

So the question with ON/OFF chip GATT database does not concern our application since the application will be a Central Device hence without profiles nor GATT database.

Could you please confirm that there is no GATT database nor profiles on a Central Device.

If understand well the application notes linked in your message we have 3 solutions :

A: Using SAP layer on CC3235 and SimpleNP on a CC2650

B: Using a custom layer on CC3235 and Host Test on the CC2652/CC2650 (could you please tell which API we can use on the CC3253)

C: Implementing the BLE communication part of the application on the Network processor and using a custom serial link protocole with the Application on the CC3235.

Which solution would you recommend for our application ?

Kind regards.

Frederic

0 Eirik V over 3 years ago in reply to Frederic Griffe

TI__Guru 56590 points

Hello Frederic,

The GAP GATT Service (GGS) is required for Bluetooth low-energy devices that implement the central or peripheral GAP role:

https://dev.ti.com/tirex/explore/content/simplelink_cc13x2_26x2_sdk_4_10_00_78/docs/ble5stack/ble_user_guide/html/ble-stack-5.x/gatt.html?highlight=ggs_addservice#gap-gatt-service-ggs

If solution C) fits your needs I would consider that for simplicity and to offload some of the processing from the CC3235. But required change in functionality on the CC2652 might require firmware update for both host device and NP device if changes to the serial communication is also required. If you expose the HCI interface and implement the host on the CC3235 you might not need to update the CC2652 as you have the fully exposed HCI API to leverage.

0 Frederic Griffe over 3 years ago in reply to Eirik V

Expert 1715 points

Hello,

Thanks for your answer.

We choosed to go for solution B, implementing HostTest on CC2650 (BoostXL as mezzanine) and using the NPI API on the CC3235 Launchpad.

We would have preferred to go for solution A but this solution is not able to act as Central Device because this solution is better supported and documented by Ti.

Could you please indicate if there are any plan to make Solution A (SAP + SNP) available as Central Device ?

Kind regards.

Frederic

0 Eirik V over 3 years ago in reply to Frederic Griffe

TI__Guru 56590 points

Hello Frederic,

I currently do not know of any plans to develop SNP further or to include Cenrtal role for it.

0 Frederic Griffe over 3 years ago in reply to Eirik V

Expert 1715 points

What would be the difficult points to extend SNP to Central Rôle ?

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CCS/CC2652R: Relation between HCI and NPI