IWRL6432: First time flashing on custom PCB

Tool/software:

Hello,

I've created my own PCB, heavily based on the IWRL6432FSPEVM, but I've gone for "BOM Optimised", so all running off a single 1.8V.

I'm using a FT230XQ USB-UART converter, straight into the IWRL6432 balls E10 & F11.

I have powered up the board, all my power supplies are present, I can see VBGAP = 0.9V in functional mode. If I change to flashing mode the the VBGAP is square-waved (like "Device Wake-up Sequence" shows in the checklist). So I'm fairly sure my device is cycling through the boot sequence as it hasn't anything in the flash yet..?

However, when I try loading the Motion and Presence binary using the SDK visualizer (MMWAVE_L_SDK_05_05_00_02), it just fails - the UART TX signal is pulled low and remains low.

The IWRL6432 TX signal is sending 8.6us pulses every 86.6us.

• I noticed another forum post that suggested the sysconfig file needed to have the correct flash device listed (I'm using MX25R1635FZUIH0, which is listed as one of the supported ones), but the post was two years old - is this still the case?
• Is there any first time boot stuff I need to do? Or should I just be able to flash an image straight onto a flash device?
• I see some of the other posts recommend running the QSPI Flash Diag. Is it possible to run this over UART to the IWRL6432? How can I setup my CCS to do this, for "Target Configurations" > "UARTConnection" I only see AWR1443 & IWR1443.

Thanks,

Peter