topic Re: does the rcw source relate to JTAG function in T-Series

does the rcw source relate to JTAG function

alpha_beta_gama — Wed, 21 Jan 2026 15:18:41 GMT

i am using T4240, and i am comfused about rcw source and JTAG function. Can i use JTAG function (to download program) when i set rcw source to SD/Nor/Nand? Or JTAG is only usable when rcw source is set to hard-coded rcw?

Another question is what the difference between RAM/SRAM/ROM when building a bareboard project? Does it matter when i run or debug it via JTAG?

Re: does the rcw source relate to JTAG function

Oswalag — Thu, 22 Jan 2026 17:11:27 GMT

Hello,

You may use JTAG irrespective of whether the Reset Configuration Word (RCW) source is set to SD, NOR, NAND, or hard‑coded, provided that the system-on-chip (SoC) successfully completes the power‑on reset sequence, all required clocks are operating correctly, and the debug interface has not been intentionally disabled or secured through RCW settings or secure‑boot mechanisms.

The distinctions among ROM, SRAM, and RAM builds primarily concern the code placement and the system initialization requirements:

- SRAM: Suitable for early hardware bring‑up, as it does not require DDR initialization.

- RAM (DDR): Requires DDR memory to be initialized beforehand, either through PBI/u‑boot or via a JTAG‑based initialization procedure.

- ROM: Intended for standalone bootable images, while still allowing debugging after the system has been started.

Re: does the rcw source relate to JTAG function

alpha_beta_gama — Sat, 24 Jan 2026 11:41:05 GMT

Thank you for your support.