Serious Issue: Programming the BCM20736S on a custom PCB

[Anonymous]

Sorry Broadcom but I have serious programming issues with the BCM20736S powered at 2,5V with a FTDI TTL-232RG-VIP-WE cable.

I have checked that the programming packet arrives to UART_RX but, on the other side, nothing happens on the UART_TX.

What I miss?

Please support our production that will start next monday.

Thank you in advance.

[Anonymous]

Can you post a snippet from the download log file that is in the WICED build folder?

[Anonymous]

I'm curious, why you are using the VIP cable. re you powering the board via battery or other power source besides the cable during download?

In my setup we use the TTL-232RG-VREG3V3-WE  which is similar to the VIP but in the VIP, reading the datasheet, the power comes from your BLE board not from the cable.  When I download, my board is powered off and the power comes through the cable from the laptop to the BLE board.  So the red wire supplies the voltage from the PC to the BLE chip... whereas in the VIP cable you are expected to provide the power to the cable via the red wire (VCC).

I don't know if it matters, just asking.

[MichaelF_56]

We have had many users in the past struggle with the programming of their custom board because they selected the wrong FTDI cable.

[Anonymous]

Hello Dtluigi,

We recommend what Eric uses.  Please go to the BLOG post that discusses which cable to use:

Programming the TAG2/TAG3 Board using command line tools

Hope this helps

Thanks

JT

[Anonymous]

I found the issue: a small capacitor (100nF) on the SDA pin towards ground. Without it, all works correctly even with the FTDI cable previously indicated.

Still a question: I can't do the recovery of the device (it fails all times) with a switch on SDA towards ground...could it be still an issue or is it normal when the programming is correctly executed?

[Anonymous]

How long is your cable? Is there a log file? What is your build target command for recovery?