3 Replies Latest reply on May 14, 2020 8:30 PM by SheetalJ_96

    EZ-BT CYBT-423028-EVAL use HCI UART without CTS RTS

    HaZh_4665521

      For some reason I have to connect CYBT-423028-EVAL HCI UART to a USB2TTY board which has NO CTS and RTS pin.

      In one document of CYBT-423028-02, I see below description:

       

      HCI UART Connections

       

       

      The recommendations in this section apply to the HCI UART (Solder Pads 3, 4, 5, and 6). For full UART functionality, all UART signals must be connected to the Host device. If full UART functionality is not being used, and only UART RXD and TXD are desired or capable, then the following connection considerations should be followed for UART RTS and CTS:

       

       

      ■ UART RTS: Can be left floating, pulled low, or pulled high. RTS is not critical for initial firmware uploading at power on.

       

       

      ■ UART CTS: Must be pulled low to bypass flow control and to ensure that continuous data transfers are made from the host to the module.

       

       

      Then I left RTS floating, and connect CTS to GND of USB2TTY board.

      It turns out that I can not initialize the CYBT to work. But with a full UART it can work, so it should be a CTS/RTS issue.

      Here's my setting:

      RPi <===> cp2102 USB2TTY bridge board <===> tx/rx/GND 3 wire <===> BT board External HCI (J1)

       

      Is there any way to make it work with only RXD/TXD?