3 Replies Latest reply on Sep 19, 2019 11:01 PM by XinghaoZ_26

    is hardware handshake must on HCI_UART lines?




      Testing A2DP source functionality using 'watch' demo app and Client control on PC, using CYBT-343026.


      In our actual application, we will be streaming audio data over I2S bus.

      While using serial HCI uart to communicate with host microcontroller.


      We would like to know, at 115200 baud rate, do we need to implement Hardware handshake using RTS/CTS lines?


      Can we enter the HCI mode on CYBT-343016, (as mentioned in blog by Owen_Z in https://community.cypress.com/community/wiced-studio-blueooth/wiced-studio-bluetooth-forums/blog/2019/06/27/run-cyw20706-in-hci-mode) by just pulling high, CTS pin at reset then maintaining it low, and then simply leaving CTS, RTS line in fixed conditions. Host microcontroller UART will communicate without hardware handshake, while maintaining a serial buffer in it's firmware.


      What could be the perceived issues using above approach.


      Any insight will be appreciated.


      Best Regards,


        • 1. Re: is hardware handshake must on HCI_UART lines?

          If you are using the HCI UART port, you must use the flow control which means you must use CTS/RTS.

          For watch demo, it uses WICED HCI Protocol. The device will accept the WICED HCI command. You can find the details in doc/WICED-HCI-Control-Protocol.pdf. It is implemented in the application code, you don't need to enter HCI mode.

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          • 2. Re: is hardware handshake must on HCI_UART lines?

            OK, got it, specification wise hardware flow control is mandated.


            But if We try NOT to use hardware handshake, can we get by ?

            What we are asking is,
            Any one tried practically to use without handshake?


            We understand, Cypress will not guarantee the reliable operation without hardware flow control.

            But leaving any edge case operations, can we achieve moderate reliability in simple command settings over HCI uart,
            No continuous or large data transfer operations expected without hardware handshake.


            This will save couple of port pins on host microcontroller.


            Any guesswork or idea sharing, without binding commitment.

            • 3. Re: is hardware handshake must on HCI_UART lines?

              If you don't want to use flow control, you may use the PUART to communicate and define the command by yourself.

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