Boot Time of WICED Smart Tag Board (BCM20737)

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Anonymous
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Hi all,

I want to know the boot time of BCM20737 Chip on WICED Smart Tag Board. I can't find any information from datasheet or in the community. If you know or ever measured the boot time, please let me know. Thanks!

I have tried to roughly measure the boot time, here are the steps:

1.  Upload the code to ROM so the chip can boot up directly from a power source (Coin Battery etc.)

2. I have designed a very simple switching circuit, so I can supply a pulse as the power source to WICED Smart Tag. I gradually change the pulse width and see whether the chip is booted or not.

3. When BCM20737 chip is booted, it will execute the code, this code will indicate the power supply circuit that chip is already on, then a real power supply will be applied to the WICED Smart Tag Board and keep it on.

So the possible results are:

1) If the boot time is too long and chip cannot be booted during the pulse width, the Tag Board won't start after the pulse turned down.

2) If the chip can be booted and execute the code successfully, a real power supply can keep the Tag Board on even the pulse turned down.


My measurement result is: If the pulse width is 1.5 second, the WICED Smart Tag Board won't start. If the pulse width is 2 seconds, it keeps on. So it seems that the WICED Smart Tag Board needs 1.5 to 2 seconds to boot up.


I think it is too long for a chip. How can we reduce the boot time? Is it related to the SDK version?


I am appreciate for any information or discussions. Thanks!

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1 Solution

Yes, loading application and patches and applying the patches to the

internal ROM image is what takes the time. This is why it varies from one

SDK version to the next.. More / different patches.

In our case we have three seconds of buffering in the accelerometer so we

can respond ok with a pretty long boot time, but in SDK 2.2 it was too much.

If you need faster response the only thing to do is never go to hidoff

mode.. but then you have a battery problem. The lowest idle time cost I

have seen with this chip is 40 microamps.

On May 30, 2015 3:31 PM, "noalac" <communities-list@community.broadcom.com>

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