AWR1642BOOST: How is mailbox being used by mmwave control link library?

Hi,

Can you provide more details - what is happening at the time of the assert?  Does the assert happen during config, when the chirps are started, or later?  Is this code based on the mmw demo, or is it entirely new?  If based on the demo, what have you changed?

  -dave

Hi Dave,

I'm using mmw demo in the SDK, but I've made modifications to the code.

Modifications:
  After angle estimation, copying the detections information into HSRAM and then sending a message to MSS via Mailbox to transmit this information over UART. Before sending the message to MSS, I'm decrementing the "gMmwDssMCB.dataPathContext.interFrameProcToken--;" and removed "interFrameProcToken--" in the switch case "MMWDEMO_MSS2DSS_DETOBJ_SHIPPED:", so that this decrement happens only once per frame.

The assert is random, but it doesn't come when configuring the sensor. I think the reason for this assert is the mailbox channel id is not getting matched (like gMailboxMCB.mssDssReadChIDInUse != driver->cfg.chId). It seems that both the mailbox channels are clashing. 

Could you please explain how important is this mailbox in mmwave link library and suggest me how to avoid this.

Thanks,
Chidvilas

Hi Chidvilas,

>After angle estimation, copying the detections information into HSRAM and then sending a message to MSS via Mailbox to transmit this information over UART

There should be no need to add another transfer, and related code. See MmwDemo_DSS_SendProcessOutputToMSS; if you need a different object to be sent, the best way is to define another TLV and send it with the existing frame rate transfer.

  -dave

Hi Dave,

We are using a different format to transfer over UART.

In mmw demo, frame periodicity should be configured such that it includes chirp acquisition time, the processing time and UART transmission time. I want to remove the dependency of UART transmission time in the frame time configured.

Can you please explain, why this mailbox clash happens? What is the role of the mailbox in mmwave link library?

Thanks,
Chidvilas

>. I want to remove the dependency of UART transmission time in the frame time configured.

This is not a good idea, because even if the frame time did include the UART transmission time, the UART transfer is not done by the DSS, but rather by the MSS so that it is not bound by the upcoming frame boundary.

Please read the TRM chapter on the Mailbox peripheral.  You'll find that there are 6 independent mailboxes, one for each direction for each pair of cores.  The BSS mailboxes are used to communicate with the DSS and MSS, and are independent of the DSS <-> MSS mailboxes.  There cannot be a "clash".  Mostly likely your configuration is not setting up the required RTOS objects correctly.  I stand by my earlier statement - your best bet is to add a new data type (a TLV) to the existing frame rate transfer.

  -dave

Hi Dave,

Understood your concern on UART changes, since we're not using TLV format our UART payload is very small, takes few milliseconds time to transmit and it is finishing within the chirps acquisition time itself.

In the SDK mmw demo, in both, "mss_mmw.cfg" and "dss_mmw.cfg" files mailbox component is not used, so I think the mailbox in "ti/drivers/mailbox" is getting used by the demo(not the TI-RTOS mailbox).

I think mailbox_write is being used by both mmw demo(modified) and mmwave link library at the same time and then for mmwave link library Mailbox_write is returning "MAILBOX_ECHINUSE".

My inference is based on the value(post crash): gMailboxMCB.mssDssWriteChIDInUse = 0 (i.e. mailbox channel 0 is being in use(by mmw demo))

so the following code in "ti/drivers/mailbox/src/mailbox.c:Mailbox_write" would return "MAILBOX_ECHINUSE":

622: /* Critical Section Protection*/
        key = HwiP_disable();
        if(gMailboxMCB.mssDssWriteChIDInUse == MAILBOX_UNUSED_CHANNEL_ID)
        {
            /* Mark that the TX mailbox is now in use*/
            gMailboxMCB.mssDssWriteChIDInUse = driver->cfg.chId;
            /* Release the critical section: */
            HwiP_restore(key);
        }
        else
        {
            /* Error: TX mailbox is being used by another mailbox instance*/
            DebugP_log2 ("MAILBOX: Mailbox_write Error! handle=(%p). Write attempt with TX box in use by channel ID %d\n",driver, gMailboxMCB.mssDssWriteChIDInUse);
            retVal = MAILBOX_ECHINUSE;
            /* Release the critical section: */
            HwiP_restore(key);
            goto exit;
 639: }

Crash report when this happens,

{module#8}: "platform/mmwave_xwr16xx.c", line 1342: error {id:0x10000, args:[0x81bbec, 0x81bbec]}
xdc.runtime.Error.raise: terminating execution
[Cortex_R4_0] xdc.runtime.Main: "mss/mss_main.c", line 3504: assertion failure
xdc.runtime.Error.raise: terminating execution

Could you help me in resolving this issue?

Thanks,
Chidvilas

Please provide an update on this.

Thanks, 
Chidvilas