2 Replies Latest reply on Jul 5, 2019 7:02 AM by NiMc_4245981

    How do I send extended PD messages?


      I'm trying to send an extended message from a CY4531 acting as a source to a device with a CCG3.  I see that the dpm_pd_command can take DPM_CMD_SEND_EXTENDED as an argument, but I can't get that to work.  Here is what I have.


      static uint8_t g_buffer[2] = {0};



      bool get_fw_id()


      dpm_pd_cmd_buf_t cmd = {0};


      // USB Power Deliver Firmware Update

      g_buffer[0] = 1;    // Protocol Version

      g_buffer[1] = 0x81; // GET_FW_ID


      cmd.cmd_sop = SOP;

      cmd.extd_type = EXTD_MSG_FW_UPDATE_REQ;

      cmd.extd_hdr.val = 0;

      cmd.extd_hdr.extd.data_size = 2;

      cmd.no_of_cmd_do = 0;

      cmd.dat_ptr = g_buffer;



      if (dpm_pd_command(0, DPM_CMD_SEND_EXTENDED, &cmd, NULL) != CCG_STAT_SUCCESS)

         return false;


      return true;



      I see the command is sent using the EZ-PD protocol analyzer, as in the screenshot below.  The header (0x8DAA) looks correct, but it is missing the extended message header and the two bytes of payload.




      What else do I need to do to send a full extended message?

        • 1. Re: How do I send extended PD messages?

          Hi ,


          I could like to recommend you refer below example to send DPM_CMD_SEND_EXTENDED.  This is implemented in app.c function void app_event_handler(uint8_t port, app_evt_t evt, const void* dat).


                  case APP_EVT_ALERT_RECEIVED:

                      /* Respond to ALERT message only if there is the number of object is one. */

                      if (((pd_packet_t*)dat)->len == 1)


                          alert_ado = ((pd_packet_t*)dat)->dat[0];

                          if(alert_ado.ado_alert.bat_status_change == false)


                              dpm_pd_command(port, DPM_CMD_GET_STATUS, NULL, NULL);




                              uint8_t i = alert_ado.ado_alert.fixed_bats |

                                  (alert_ado.ado_alert.hot_swap_bats << 4);

                              dpm_pd_cmd_buf_t cmd;



                              /* Identify the first battery for which the change is intended. */

                              get_bat_status[port] = 0;

                              while ((i != 0) && ((i & 0x01) == 0))



                                  i >>= 1;




                              cmd.cmd_sop = SOP;

                              cmd.extd_hdr.val = 0x1;

                              cmd.timeout = PD_SENDER_RESPONSE_TIMER_PERIOD;

                              cmd.extd_type = EXTD_MSG_GET_BAT_STATUS;

                              cmd.dat_ptr = (uint8_t*)&get_bat_status[port];

                              dpm_pd_command(port, DPM_CMD_SEND_EXTENDED, &cmd, NULL);





          Before you fill the "cmd", you can see the structure in pd.h. And then, you should fill the structure as per your message.



          * @brief Struct to hold PD command buffer.

          * @warning When providing pointer to the extended data make sure original buffer

          * is always 4-byte aligned. i.e, even if 1 byte data is required, 4 bytes should be used to

          * store that data.


          typedef struct


              sop_t               cmd_sop;                /**< SOP type */

              extd_msg_t          extd_type;              /**< Extended Message Type */

              pd_extd_hdr_t       extd_hdr;               /**< Extended Header */

              uint8_t             no_of_cmd_do;           /**< No of data objects including VDM header */

              uint8_t*            dat_ptr;                /**< Data Pointer in case of extended message only*/

              uint8_t             timeout;                /**< Timeout value, in ms, for a response.

                                                           *   If set to zero, the PD stack will not wait for a VDM response

                                                           *   and jump to ready state after this buffer has been sent.


              pd_do_t             cmd_do[MAX_NO_OF_DO];   /**< Command data objects. */

          } dpm_pd_cmd_buf_t;


          Best Regards,


          1 of 1 people found this helpful
          • 2. Re: How do I send extended PD messages?

            I have trouble even when I use the APP_EVT_ALERT_RECEIVED code.   The data that is sent is 0x9DAA, 0x8400.  The last two zeros should be the extd.data_size, but it is zero.  Therefore the data byte is missing.  the data_size is set in the command passed to dpm_pd_command(), but it seems like that function is setting it to zero before sending it.


            2019-07-05 09_37_10-EZ-PD Analyzer Utility.png